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Equipment Discussions >> Classic Telescopes

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orion61

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Reged: 10/20/07

Loc: Birthplace James T Kirk
C8 Grounding question
      #5606092 - 01/05/13 07:58 AM

I have an early Sandcast C8 but it only has a 2 prong plug,my
others have the 3 prong shielded cable, I use a drive converter but we are still at 110V AC. outside in dewy grass, Am I going to electrocute myself?


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dgreyson
scholastic sledgehammer
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Reged: 11/06/12

Loc: South Carolina
Re: C8 Grounding question new [Re: orion61]
      #5606314 - 01/05/13 10:57 AM

oh Phui!! Man up! Touching your eye to a metal telescope thats wet with dew while standing on a good earth ground?? If your lucky you may just be severely injured.

The synchronus motor windings can overheat, swell up, short against the motor casing and connect 110 volts to the frame.

I doubt the telescope is double grounded if the gears are metal so a three prong plug is better than none. If you need to keep the integrity of your scope as is, just use a Ground fault interrupter extension cable. If you ever get your drive corrector working, you are safe if using a car battery as the power source because the output is isolated and so isnt referenced to ground like line voltage is. If you use the same AC socket, have it changed out to a gfi socket like they put in the bathroom and you can use a regular extension. You still can get a nasty shock until the gfi trips but it should interrupt the current before it gets lethal. ME, I'd use a 3 prong cord and a GFI, but that's only because I seriously plan on outliving my dog.

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apfever
Carpal Tunnel
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Re: C8 Grounding question new [Re: dgreyson]
      #5606438 - 01/05/13 11:56 AM

nice disclaimer. No comment.

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desertrefugee
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Reged: 08/06/07

Loc: Arizona
Re: C8 Grounding question new [Re: apfever]
      #5606823 - 01/05/13 03:21 PM

"Not the Beatles" !??

Then forget it.


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Littlegreenman
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Loc: Southern California
Re: C8 Grounding question new [Re: desertrefugee]
      #5606945 - 01/05/13 04:44 PM

Maybe someone knows if running it offer a battery pack reduces any shock or electrocution risk?

Disclaimer This posts has no disclaimers.

LGM


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desertrefugee
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Reged: 08/06/07

Loc: Arizona
Re: C8 Grounding question new [Re: Littlegreenman]
      #5607041 - 01/05/13 05:56 PM

Quote:

Maybe someone knows if running it offer a battery pack reduces any shock or electrocution risk?

Disclaimer This posts has no disclaimers.

LGM




120VAC is still 120VAC - even if it has been inverted from 12VDC. Power delivery varies by inverter, but in general, most of the same cautions should apply. There's no current limiting in place and the unit will deliver until the fuse/breaker terminates the circuit.

As little as 10mA to the heart will stop it. That's not a lot of current. Given perfect (or imperfect) conditions, moisture, point of application, electrocution could occur.

No disclaimers. Just casual observations by one who works in the cardiac rhythm management business.


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orion61

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Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: C8 Grounding question new [Re: desertrefugee]
      #5607066 - 01/05/13 06:06 PM

I have a newer base I could pull the forks off and mount it on that. It is 3 prong, and I wouldn't mess with the origonal base, I couldn't deface it! I'm a huge fan of restoring these old beauties, as a matter of fact I am doing one right now for a friend..
PM for details.. there is a thread about it around here somewhere...LOL


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dgreyson
scholastic sledgehammer
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Loc: South Carolina
Re: C8 Grounding question new [Re: orion61]
      #5607129 - 01/05/13 06:36 PM

Cool, I feel the same, If its something vintage, Id rather have it factory original. Except for my corvette, I had that *BLEEP* tricked out for speed. It got 12 mpg but it would blow the doors off of anyone elses heap. when gas went above 35 cents a gallon I had to reluctantly sell it coz it was taking all my beer money.

As far as Electric shocks go, Wall voltage is different from inverted voltage. Household current is one leg of a 220v circuit that is referenced to earth ground. If you touch the hot lead, current will flow thru you to the ground and shock you. it only takes a single wire. Ive also gotten shocked from the neutral lead as well, dunno why. (used to know but forget) If you touch one leg of an inverter generated circuit, wou shouldnt be electrocuted because it "Floats" above the earth ground. You would need to touch both legs of the inverter output to make a circuit that current could flow through. Thats why I said it was Safer. you would need to bridge across the output to get a shock while AC line will kill you if you touch just one wire or the circuit has a short to the casing. If one side of the inverter output shorts to the casing, you likely would not feel a shock. I'd say you couldnt except I stopped saying absolutes when the second space shuttle blew up. Anything can go wrong.

see legal disclaimer above.


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Littlegreenman
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Re: C8 Grounding question new [Re: desertrefugee]
      #5607202 - 01/05/13 07:50 PM

Quote:

Quote:

Maybe someone knows if running it offer a battery pack reduces any shock or electrocution risk?

Disclaimer This posts has no disclaimers.

LGM




120VAC is still 120VAC - even if it has been inverted from 12VDC. Power delivery varies by inverter, but in general, most of the same cautions should apply. There's no current limiting in place and the unit will deliver until the fuse/breaker terminates the circuit.

As little as 10mA to the heart will stop it. That's not a lot of current. Given perfect (or imperfect) conditions, moisture, point of application, electrocution could occur.

No disclaimers. Just casual observations by one who works in the cardiac rhythm management business.




Thanks for the reply. Now I know.

I think I'll get a gravity driven clock drive...


SL


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dgreyson
scholastic sledgehammer
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Re: C8 Grounding question new [Re: Littlegreenman]
      #5607276 - 01/05/13 08:50 PM

[quote
Thanks for the reply. Now I know.

I think I'll get a gravity driven clock drive...





You would only mash your toes when you drop a weight and get gangrene. Or you could put your eye out if the mainspring broke or something. No, It's much safer if you get someone else to look thru it and describe what they see to you. You might think that if you stayed home and let them sketch it on a paper and bring it to you that would be safest but your wrong. Because their nasty germs would be on it and you may catch a desperate illness. No no.


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orion61

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Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: C8 Grounding question new [Re: dgreyson]
      #5607302 - 01/05/13 09:06 PM

You know if some one could come up with an inexpensive Wind up Clock drive, I'd be ALL over it for general observing!
I'd even try it with go-to... just give me that BIG key
like the Robots in the 50's had in back LOL
I'm serious tho about having a visual mount with a mechanical clock drive.. they could be made...


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johntrob
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Reged: 03/14/11

Loc: Georgia, USA
Re: C8 Grounding question new [Re: orion61]
      #5607377 - 01/05/13 10:05 PM

Remember the old refrigerators, grab the handle and get a charge, still alive.

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dgreyson
scholastic sledgehammer
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Reged: 11/06/12

Loc: South Carolina
Re: C8 Grounding question new [Re: johntrob]
      #5607581 - 01/06/13 12:00 AM

we had an old metal chest freezer on the concrete carport slab and if you forgot you were barefoot and grabbed the handle to get something it would knock the fool out of you.
I'm sure it could have killed someone under the right conditions, say wet concrete. The adults never knew it of course because they always wore shoes. But it was nowhere near the shocks I used to get from Microphones when I was in a band and they had the amp plugged in wrong so I never thought much about it or told anyone. Just part of doing business I guess.


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dgreyson
scholastic sledgehammer
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Loc: South Carolina
Re: C8 Grounding question new [Re: orion61]
      #5607590 - 01/06/13 12:03 AM

Quote:

I'm serious tho about having a visual mount with a mechanical clock drive.. they could be made...




I wonder how troublesome the mechanical drives were on Unitrons? they used weights on a chain like a grandfather or a cukoo clock.

here is a thread about them
mechanical clock drives - post a picture


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actionhac
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Re: C8 Grounding question new [Re: dgreyson]
      #5607640 - 01/06/13 12:48 AM

It wouldn't hurt to ground our 110V drives.
Its surprising how easy it is to kill one's self.
I guess we don't think of the danger because we can't see it.
We can buy a appliance cord with a 3prong plug and connect white-white, blk-blk, and ground the green to the drive motor mounting bolts.
Or a 6ft 3prong extension cord and cut off the female and hard wire it in the same as above.
I know its not original but it may save a life under the right circumstances.
Have I done it myself? no I haven't! I'm so lazy. No that's not really it I'm a real stickler for originality is the real reason and yes it will be chiseled onto my tombstone no doubt.
I've been shocked many times, I work with electricity in my job. Sometimes its just a little tingle and other times it has left me with a sore arm. A few times I blinded myself for the rest of the day.

Robert


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DAVIDG
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Re: C8 Grounding question new [Re: actionhac]
      #5608157 - 01/06/13 11:41 AM

I just checked my two old sand cast C-8 mounts with the two prong Jones plug. There is Continuity between the motor housing and the unpainted back of the mount, but none to any painted section of the mount.
While the paint is not a perfect solution it does provide some protection.
A simple solution is to make up a new cord using a three wire grounded plug. At the Jones plug, pull out the green grounding wire and attach it to one of the screws that hold the male Jones plug into the mounting base. Now the scope is grounded as long as you use a grounded outlet with hopefully a GIF on it.
I also have Criterion RV-6 and when I restored in many years ago, I replaced the original cord with a three wire molded one and attached the ground wire to one of the bolts on the motor mount.

- Dave


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tim53
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Reged: 12/17/04

Loc: Highland Park, CA
Re: C8 Grounding question new [Re: orion61]
      #5608308 - 01/06/13 12:56 PM

Quote:

You know if some one could come up with an inexpensive Wind up Clock drive, I'd be ALL over it for general observing!
I'd even try it with go-to... just give me that BIG key
like the Robots in the 50's had in back LOL
I'm serious tho about having a visual mount with a mechanical clock drive.. they could be made...




a couple years back, I bid on a drive base for a 70s C8 that was made by Optica b/c, IIRC. Very cool unit with a worm drive. Though not original to the scope, it was of the same vintage. Kind of like one of those retrofits to the C-14 drive made by Ed Byers, only this one was entirely non-Celestron manufacture.

I'm pretty sure it was 110V, though Matters little, as I lost the bidding.

-Tim.


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PiSigma
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Loc: North Carolina
Re: C8 Grounding question new [Re: DAVIDG]
      #5608316 - 01/06/13 12:58 PM

In order to keep my scopes original (two prong plug, ungrounded) and safe I have made up a cord with just the ground wire at the AC plug and an alligator clip on the other end. I run a grounded extension cord and power strip to the scope and plug the scope and my extra ground lead into the strip, then clip the alligator clip to the scope's motor housing. Everything is then grounded and originality maintained.

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tim53
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Reged: 12/17/04

Loc: Highland Park, CA
Re: C8 Grounding question new [Re: tim53]
      #5608340 - 01/06/13 01:08 PM

Does anyone know of DC servo motors that wouldn't need more room than the stock Synchronous motors in the C-8 drive base?

Because, if there are, and they have encoders built in like the Pittmans (which are too big to fit the space in a Celestron drive base), I could imagine converting one to goto with all the cool software like PointXP that comes with the Sidereal Technology goto kit. Within wide limits, you can set the drive rate for specific gear ratios in software.

I did this with my Tak Em-500 mount for about a year or so before Dave Groski repaired the original non-goto controller for me (that I'd fried an IC on because I thought ALL Taks were 24V, but the old ones weren't). Worked very well, though I never used the goto feature because I used the mount for planetary only at the time. Still have the Sitech kit to put in/on another mount, but I'll probably put it on the big Springfield mount I bought a few years ago, which has no drive as yet (no motors, that is, it's got an 11" RA gear!).

I don't like dying before I'm spent, and I'm hoping that's going to be a long time from now. You guys are scaring me about these old AC drives, now. I wouldn't be averse to converting a classic to a DC system if (and only if) it could be completely reversible. Bolt-in only for me for some of these old scopes. If I made such a conversion, I'd keep the original parts - kind of like we keep those screw in sun filters that come with our classic refractors - so everything could be put back to original as the scope's value increases to warrant that.

-Tim.


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orion61

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Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: C8 Grounding question new [Re: PiSigma]
      #5608350 - 01/06/13 01:14 PM

I remember as a Kid we used to have a lawn Mower with a big wind up crank that would turn the motor over when released.
It worked great i wonder why they stopped making them..
We have a Clock maker/Repairman who still works on the old time clocks,pocket watches and anything with gears.
I ownder if he could think of something. I'll bet
there would be a market in the Classifieds for us old timers that would appreciate such crafstmanship!
I know I would buy one in a heartbeat..


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actionhac
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Loc: Seattle
Re: C8 Grounding question new [Re: orion61]
      #5608752 - 01/06/13 04:22 PM

Our mower had that feature. Wind it up, stand back, push the button. Pretty scary like starting the red baron's fighter plane, wild and crazy. Very reliable though, no rope to break. I remember it well. It was a vertical shaft engine so I couldn't use it on a go-kart, too bad.

TASCO sold a wind-up. 20min run time. #1602-M Look in here:
http://geogdata.csun.edu/~voltaire/classics/tasco/tasco1968.pdf

YOU CAN BUY "portable" GFI protection as a strip or built into a extension cord like here:
http://www.cpsc.gov/cpscpub/pubs/099.pdf

Robert


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dgreyson
scholastic sledgehammer
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Loc: South Carolina
Re: C8 Grounding question new [Re: actionhac]
      #5609826 - 01/07/13 09:43 AM

Home depot has a $30, 2 foot long Ground fault extension cord you plug into the wall socket and then plug a regular extension into. As long as you have a 3 prong outlet to plug the GFI adaptor into, it protects you from shocks even if your drive adaptor is 2 prong. Lowes and walmart also sell them.

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Geo.
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Reged: 10/01/08

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Re: C8 Grounding question new [Re: dgreyson]
      #5612366 - 01/08/13 05:30 PM

In Australia clocks run on 240v. Here's a link to a discussion and some options to deal with old AC motors:
http://sound.westhost.com/clocks/ocm.html


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dgreyson
scholastic sledgehammer
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Re: C8 Grounding question new [Re: Geo.]
      #5612634 - 01/08/13 08:14 PM

Quote:

In Australia clocks run on 240v.


That means that If you grab hold of a shorted telescope and you get hit with 220 volts, you would shortly be "Down under"

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rmollise
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Re: C8 Grounding question new [Re: DAVIDG]
      #5613360 - 01/09/13 09:17 AM

Quote:

I just checked my two old sand cast C-8 mounts with the two prong Jones plug. There is Continuity between the motor housing and the unpainted back of the mount, but none to any painted section of the mount.
While the paint is not a perfect solution it does provide some protection.
A simple solution is to make up a new cord using a three wire grounded plug. At the Jones plug, pull out the green grounding wire and attach it to one of the screws that hold the male Jones plug into the mounting base. Now the scope is grounded as long as you use a grounded outlet with hopefully a GIF on it.
I also have Criterion RV-6 and when I restored in many years ago, I replaced the original cord with a three wire molded one and attached the ground wire to one of the bolts on the motor mount.

- Dave




This will do it, and is maybe not a bad idea...with a couple of caveats:

1. If you are inexperienced with electrical work, leave it alone. If you simply must have a three prong cord on your C8, have someone who knows what they are doing install it. Some famous last words: "Nothing to it."

2. I do not recall ever hearing, over the past 43 years, of anyone being electrocuted by a dadgum C8.


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rmollise
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Re: C8 Grounding question new [Re: Littlegreenman]
      #5613366 - 01/09/13 09:19 AM

Quote:

Maybe someone knows if running it offer a battery pack reduces any shock or electrocution risk?






No it does not. How could it? 1 amp of inverter produced AC is exactly the same as 1 amp of AC coming out of the wall and will kill you just as pea-picking dead.


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actionhac
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Re: C8 Grounding question new [Re: rmollise]
      #5613567 - 01/09/13 11:45 AM

I was reading its difficult to get the heart beating again once it stops.
A defibrillator is really only to correct an abnormal rhythm.
I guess it doesn't matter no one I know has a defibrillator anyway.
The key though is not to provide a path for the electricity to flow across your heart to ground, like touching the mount with one hand and having the opposite foot in a puddle of water. Or making a easier path using your body than going through the mount legs. The electricity will take the path of least resistance.
In other words probably put one hand in your pocket if you are fiddling with your mount or cords and everything is wet with dew. And wear shoes.

Robert


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kansas skies
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Reged: 12/02/12

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Re: C8 Grounding question new [Re: actionhac]
      #5613712 - 01/09/13 01:14 PM

Grounding equipment doesn't necessarily make it safe. While grounding the chassis or case of a piece of equipment can remove the possibility of having voltage levels present on the chassis, it also provides a very effective return path to ground for voltages that might be present elsewhere (on some other piece of equipment that is in use). The most effective protection would probably be to install an inline ground fault interrupter (GFI) (in addition to the ground) as was mentioned above.

Bill


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DAVIDG
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Re: C8 Grounding question new [Re: kansas skies]
      #5613729 - 01/09/13 01:29 PM

Let remember that issue with the grounding is for the very old C-8 that had the mounts that used the two prong Jones plug, that was on the side of the mount. There most likely were less then 200 of these style mounts made before Celestron changed the design to use the three prong grounded plug located on the back surface of the mount and used the oval type "HP" power cord.
So with a typical vintage orange tube C-8 or newer units, the danger has greatly been reduced. Also if one looks at the construction of typical syn. motor used to drive a telescope, the coil windings are insulated from the body of the motor. So some how a winding would need to break free, go thru the insulation around it and come in contact with the motor housing. Not impossible but pretty low odds. What the real risk comes from is the extension cord used to power the scope. This is were most problems occur from the use of one that is damaged and having exposed wires and/or one that is not a three wire grounded type and/or plugging it into a non grounded outlet. So anyone using a AC powered scope should double check the cord they use, use a three wire grounded one and be sure that it is plugged into GFI outlet.

- Dave


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dgreyson
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Re: C8 Grounding question new [Re: rmollise]
      #5613774 - 01/09/13 01:55 PM

Quote:

2. I do not recall ever hearing, over the past 43 years, of anyone being electrocuted by a dadgum C8.




Richard Feynman in his dissent to the Rodgers commission report on the Challenger space shuttle disaster, Appendix F, cites this very logical fallacy:

Quote:

"It appears that there are enormous differences of opinion as to the probability of a failure with loss of vehicle and of human life... We have also found that certification criteria used in Flight Readiness Reviews often develop a gradually decreasing strictness. The argument that the same risk was flown before without failure is often accepted as an argument for the safety of accepting it again. Because of this, obvious weaknesses are accepted again and again, sometimes without a sufficiently serious attempt to remedy them, or to delay a flight because of their continued presence... The acceptance and success of these flights is taken as evidence of safety. But erosion and blow-by are not what the design expected. They are warnings that something is wrong. The equipment is not operating as expected, and therefore there is a danger that it can operate with even wider deviations in this unexpected and not thoroughly understood way. The fact that this danger did not lead to a catastrophe before is no guarantee that it will not the next time."
Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident




In other words, the O rings had never caused the shuttle to explode, despite obvious evidence of hot gas blow by and burn erosion thru the ring wall so therefore nothing is a problem and the Shuttle is Safe to fly.

All activities come with a certain amount of risk, one has to manage risk by taking steps to increase safety and minimize danger.

The impression is being given that all c8's are unsafe, which is not true indeed. the three prong double insulated ones are not what we are talking about. Rather, I mean any classic telescope made before the UL code mandated three prong grounding and double insulation of electrical devices. Cave Astrolas & etc, are just as dangerous. Worn extension cords are indeed a more likely hazard, the takeaway point here is that there is a very good reason undgrounded electrical devices are prohibited by code.


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rmollise
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Re: C8 Grounding question new [Re: dgreyson]
      #5613810 - 01/09/13 02:19 PM

Quote:

Astrolas & etc, are just as dangerous. Worn extension cords are indeed a more likely hazard, the takeaway point here is that there is a very good reason undgrounded electrical devices are prohibited by code.




Which is why I said, yeah, that grounding these things is probably a good thing. But, the awesome Feyman not withstanding, I know of no one succumbing to death due to C8 or from Colonel Mustard in the library..


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dgreyson
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Re: C8 Grounding question new [Re: rmollise]
      #5613870 - 01/09/13 02:58 PM

Quote:

But, the awesome Feyman not withstanding, I know of no one succumbing to death due to C8 or from Colonel Mustard in the library..




People dying by electrocution trying to use a telescope you say? Sure, it happens. ok, they really do not say whether it was a C8 or not, but:
Man dies of electrocution trying to watch meteor shower


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PiSigma
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Re: C8 Grounding question new [Re: DAVIDG]
      #5613913 - 01/09/13 03:17 PM

My 1976 C8 has the two prong Jones plug so I think it is a lot more than 200 units. Didn't the change to the 3 pin HP plug occur when they went from sand cast to die cast forks?

And didn't someone here have a picture of the three prong HP socket and internally the ground pin wasn't even connected to anything in the base?


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Re: C8 Grounding question new [Re: dgreyson]
      #5613979 - 01/09/13 04:04 PM

Quote:

Quote:

But, the awesome Feyman not withstanding, I know of no one succumbing to death due to C8 or from Colonel Mustard in the library..




People dying by electrocution trying to use a telescope you say? Sure, it happens. ok, they really do not say whether it was a C8 or not, but:
Man dies of electrocution trying to watch meteor shower




The article say that the person removed the cover plate on a street light and cut the live wires trying to turn off the light to get a better view thru their telescope.

" Millett was killed when hit by an electrical charge of 4,000 volts after he cut the light's main power cord."

Failure of the electrical system of the telescope had nothing to do with the electrocution but it was a willful act of the person who didn't understand what he was doing to cut thru live wires.

- Dave


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Re: C8 Grounding question new [Re: DAVIDG]
      #5614010 - 01/09/13 04:18 PM

Actually he didnt even need the telescope to see a meteor shower, but as you saw, he did indeed die by electrocution. That it wasnt the telescope that electrocuted him is an important detail, but he was certainly trying to use a telescope in the incident. so therefore: He was electrocuted while trying to use a telescope.

My question is: did the street lamp have a 3 prong cord? a GFI? I rest my case.


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kansas skies
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Re: C8 Grounding question new [Re: dgreyson]
      #5614157 - 01/09/13 05:46 PM

Maybe it's just me, but I worry more about tripping over the extension cord than getting shocked or electrocuted.

Bill


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Re: C8 Grounding question new [Re: dgreyson]
      #5614231 - 01/09/13 06:27 PM

Quote:

Quote:

But, the awesome Feyman not withstanding, I know of no one succumbing to death due to C8 or from Colonel Mustard in the library..




People dying by electrocution trying to use a telescope you say? Sure, it happens. ok, they really do not say whether it was a C8 or not, but:
Man dies of electrocution trying to watch meteor shower




Uh...eletrocuted because he cut the wires of the a streetlight. The telescope was innocent.

NOT GUILTY, YOUR HONOR!


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Re: C8 Grounding question new [Re: dgreyson]
      #5614239 - 01/09/13 06:31 PM

Quote:

Actually he didnt even need the telescope to see a meteor shower, but as you saw, he did indeed die by electrocution. That it wasnt the telescope that electrocuted him is an important detail, but he was certainly trying to use a telescope in the incident. so therefore: He was electrocuted while trying to use a telescope.





He was standing next to a Dodge Neon when he shimmied up the light pole, so I SAY THE DODGE WAS AT FAULT, COUNSELOR! WE WILL SUE CHRYSLER!


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Re: C8 Grounding question new [Re: rmollise]
      #5614277 - 01/09/13 06:48 PM

My neighbor has "hot wires" in the cattle fences out in the valley.
The intensity of this wire is adjustable and right now they are set to a relatively mild shock, mild if your a 1200lb cow!
Well it definitely will wake you up. I'm not sure how it works because we usually have knee high thick rubber boots on when we get ZAPPED.
It must be going through body tissue and exploding outward in the form of radiation into the atmosphere seeking a ground or something. I'd should see what it looks like in the dark.
Not very dangerous because very little amperage just a massive amount of voltage.

Robert


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Re: C8 Grounding question new [Re: actionhac]
      #5614436 - 01/09/13 08:10 PM

I grew up on a Farm and we ran those electric fences. Trust me they will wake you up!
FUNNIEST thing I ever saw in my life, was when our old dumb Farm dog lifted his leg on one of those Metal Fence posts!
I just happened to look back at him when he did it.
There was a big YELP and he took off running faster than I'd ever seen him run, Amd as God as My witness the tip of his tail was curled up under him and touched his chin as he ran.. Front end WAY in the air, back end WAY down low as he was running...
Next day we were walking up the lane again, he looked at that post paused and GROWLED at it.... This is a true story..


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Re: C8 Grounding question new [Re: orion61]
      #5614681 - 01/09/13 11:10 PM

Ok, I think this has been beaten to death and wandered off course a bit. I will say, if you use a drive corrector, better check inside on what they did with the grounding on the AC input and output, it may surprise you!
Brian


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Re: C8 Grounding question new [Re: orion61]
      #5614760 - 01/10/13 12:22 AM

Electric fencers operate at very high voltages, 10-20K, but very low amps. Circuits can easily run a mile. My dad would grab the wire to test them. If he got a good contracton of his arm then the fence was working well. If not, I got to patrol the line looking for weeds grounding it.

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Re: C8 Grounding question new [Re: Brian Risley]
      #5615402 - 01/10/13 12:11 PM

Brians right lets keep this thread on subject.

Rich (RLTYS)


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Joe Cepleur
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Re: C8 Grounding question new [Re: Rich (RLTYS)]
      #5626008 - 01/16/13 11:10 AM

Please could someone confirm that I understand how to prevent electrocution when using at AC powered telescope?

(1) If the scope lacks at three-prong plug, have one installed by an electrician.

(2) If an older scope has a three-prong plug, consider having an electrician check that the ground is actually properly connected.

(3) Use only heavy-duty, three-prong extension cords in perfect repair.

(4) Use only three-prong, grounded outlets. (Corollary: If only two-prong outlets are available, do not use the electric drive!)*

(5) If the available three-prong outlet is also GFI, great! If not, plug a GFI extension cord into the outlet, and the longer three-prong extension into that.

(6) Be smart. Especially when joining several extension cords together, protect the joined plugs from puddles, melting snow, or excessive dew.

And, Larry: You presumably know how to test the wiring on that orange tube's base?!

-=-=-=-=-=-

*Edit:

At http://www.cpsc.gov/cpscpub/pubs/099.pdf, I just read that "a GFCI works even on two slot receptacles." Does this mean that I do not need to worry whether the outlet is three prong or two slot, or is a three prong still better?

Edited by Joe Cepleur (01/16/13 02:58 PM)


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Re: C8 Grounding question new [Re: Joe Cepleur]
      #5626113 - 01/16/13 12:33 PM

Yes, to be reasonably safe all of those statements are valid.

GFI devices work by comparing the current going out to the current coming in. If more current is going out than coming back, the device knows that electricity is flowing to ground somewhere (a ground fault) and opens the circuit. So yes GFI affords protection even on two prongs.

The difference, is that with a three prong, the gfi trips immediately when you plug it in. On a two prong, it will trip when someone grounds themselves or a stepstool against an electrified casing and provides the missing path to ground. A three prong without GFI will hopefully trip the house breakers or fuse if the hot wire shorts to the case.

When all you have is a two prong wall outlet, do not use a 3 to 2 prong adaptor and assume the cover screw is grounded.
It likely is not. Also, just to be paranoid, just because an outlet is three prong, it doesn’t necessarily mean its grounded. Sometimes previous handyman owners will swap out the old outlet for convenience. A decent receptacle tester can be had from amazon for $7 bucks and shows by lights if the outlet is good or improperly wired when you plug it in.
If your outlet is ungrounded, use a GFI or the battery or have it fixed.

The important idea to take away with you, is that in the past, any sort of safety was not something that was much worried about. In the 1920's, it was not uncommon to see exposed conductor knife switches. If you were feeling around in the dark for the switch and put your fingers across the switch lever, you would know it immediately.

In today's lawsuit ready environment, electrical safety is considered more important. Over time, as commercial products kill and maim their customers, product designs have evolved from mortality data to reduce the manufacturer’s chance of monetary loss.

But besides taking care of your own personal safety, you really have to consider the financial ramifications from electrocuting the barefoot neighbor’s kid who runs up and wants to look through your scope and touches the frame in admiration. And it looks really bad at Outreach demonstrations when that happens.

Everyone has heard of someone’s grandpa who smoked tobacco & etc. and died at a ripe old age in perfect health. If you plug in your old scope with the rotten wires flaking off the insulation, you have a good chance of being just fine and nothing ever happening. One has to weigh the risks you are willing to accept versus the benefits and consequences and choose for yourself. No one has to do any of this if they choose not to, it is merely a good idea to do so and one takes one's chances as they like however they fall as in any activity.


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Re: C8 Grounding question new [Re: dgreyson]
      #5626235 - 01/16/13 01:48 PM

Thanks, dgreyson! I like to be careful for myself, but also feel an obligation at star parties to offer only best-practice, safe electrical cords to unwitting guests.

I actually have a receptacle tester. Used to use it in traveling sales to determine whether an outlet was on a GFI protected circuit, prior to plugging in a surge protector. Learned to do that after blowing up a customer's outlet once, while on a call in a fancy loft in the Garment District of New York. Apparently, it's one or the other, not both!

Is there any similar risk to the receptacle in plugging in a GFI extension cord, if the circuit is already GFI protected? I recall an electrician telling me that installing a GFI as the first outlet on a circuit of many protected all the outlets downstream. This opens the possibility that plain-vanilla, three-prong outlet could actually be GFI protected. Any chance I'm going to blow up yet another outlet, by adding a GFI extension where it does not belong? If there is no risk, then I should simply use a GFI extension cord whenever I do not plug directly into a GFI outlet.

Which is better (less harmful), or does it matter? Getting zapped while connected to a properly grounded, standard outlet, or a GFI outlet? It sounds as though the GFI is better, so I may as well always use it.


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Re: C8 Grounding question new [Re: Joe Cepleur]
      #5626290 - 01/16/13 02:23 PM

Sorry Joe, I'm an Electronics Tech not a Master electrician and that question exceeds my level of competence to answer.
I do not know if two GFI in series are more dangerous.

GFI is better than no GFI, I can say that with confidence.

New Hair dryers commonly come with GFI plugs and bathrooms are mandated by the NEC code to have GFI recepticals. I use a hair dryer every day in series like that and it seems to be fine. When I test the gfi by pressing the test button, both trip. So by that I presume that it isnt an issue or the dryer box would have a warning against it. (anyone going to Target or WalMart today? go look and see.)

My best guess is that it isnt any safer to have two in series as they both protect and two in series isnt a signifigant risk. That is just my guess though, your mileage may vary.

One thing to add however, GFI is looking for improper shorts to ground. If you wet your thumb and put it in a
lamp socket, current will flow from hot to neutral and the GFI is perfectly fine with that. It has no way of discerning whether it has a proper load or if someone is touching hot and neutral at the same time. So touching exposed wiring does not automatically mean the GFI will always trip. Thats the reason why you shouldnt use worn and damaged extension cords or cables.


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Re: C8 Grounding question new [Re: dgreyson]
      #5626339 - 01/16/13 02:56 PM

Quote:

GFI is looking for improper shorts to ground. If you wet your thumb and put it in a lamp socket, current will flow from hot to neutral and the GFI is perfectly fine with that. It has no way of discerning whether it has a proper load or if someone is touching hot and neutral at the same time. So touching exposed wiring does not automatically mean the GFI will always trip. Thats the reason why you shouldnt use worn and damaged extension cords or cables.




Interesting! In this case, the GFI would not help, but a proper ground would, so it would be better always to have both. It sounds as though if there is a problem at the scope, with electricity grounding far from the outlet, the GFI detects that, and cuts the power. But, if the expected amount of power were coursing through the outlet and some unlucky soul's wet thumb in the socket at the same time, only a ground would help, by being more efficient at carrying the power into the Earth than would be the body of the poor fool being electrocuted.

Good to know there is no harm to the household wiring in doubling up on GFIs. Blowing up that outlet was not one of my finer moments!


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Re: C8 Grounding question new [Re: Joe Cepleur]
      #5626421 - 01/16/13 03:42 PM

More is better one would suppose, and that the hapless person who inserts personal parts into energized electrical apparatus is risking an illuminating experience if the gods by chance were to shuffle when they should have cut.

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Re: C8 Grounding question new [Re: dgreyson]
      #5683072 - 02/16/13 09:44 AM

I bought a weather-proof, super heavy-duty, outdoor GFI extension for $30. Does it matter where it is plugged into the circuit? If I am going to run 100 feet of extension cord, is it better to install the GFI at the receptacle, or at the end of the cord just before the telescope -- or does it not matter?

This strikes me as a wise purchase for using a telescope at outreach events, which are often at older buildings with unknown electrical wiring.


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Re: C8 Grounding question new [Re: Joe Cepleur]
      #5683123 - 02/16/13 10:09 AM

Plug in your GFI extention cord as close to the supply as you can. You want to run other extention cords, or anything else out into the field, off the GFI being close to the supply.

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Re: C8 Grounding question new [Re: apfever]
      #5683331 - 02/16/13 11:48 AM

Quote:

Plug in your GFI extention cord as close to the supply as you can. You want to run other extention cords, or anything else out into the field, off the GFI being close to the supply.




Thanks! Upon hearing your answer, it makes sense. If we're going to walk through a puddle in which the connection between two extensions happens to be submerged, we want that connection to be protected by a GFI between it and the supply.


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Re: C8 Grounding question new [Re: orion61]
      #6155019 - 10/24/13 08:56 AM

The thread re-opens! A question about grounding any older telescope, or an Orange Tube C8 in particular, arose in another thread about an RV-8, so rather than hijack that one, I have moved the issue here. Picking up with a quotation from that thread:

Quote:

Quote:

Thanks, Norm. So, in theory, we can rewire any old scope. How would the new ground wire fit into the case? These old C8s use oval-ended Belden cords (if I recall the name correctly).



Joe,
If you have a C-8 that uses the Belden oval shaped cord then it is already a three wire grounded type and the middle prong on receptacle on the base is the ground prong. Here is a picture that shows both the cord and plug on the base of a C-8, with the ground pins indicated.
If you have the first generation of the orange C-8 that used the mount that used a two prong Jones plugs, then you need to add a ground. The Jones type male receptacle on the base of the mount is located on the side of the mount and not underneath and is round in shape and about 5/8" in diameter.

- Dave




DavidG to the rescue again! Thanks, Dave. You are an angel to we electrically challenged.

Part of the trouble is that, for me, a "two prong Jones plug" is something I'd find in a bin with a left-handed monkey wrench. Googling did not help much, because I can not see where this type of connector fits on the Orange C8's mount. I am currently miles from my C8, and will inspect it as soon as I can. My recollection is that the Belden cord is odd, in that there is a hole in the plug where a ground would go, yet there is no metal in the hole.

Are you saying that the mount is already grounded, if only I had the correct cord; or, that there is a way to ground it, if I could find this "Jones type male receptacle on the base of the mount," and wire it to... to what; one of the motors?


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Re: C8 Grounding question new [Re: Joe Cepleur]
      #6155208 - 10/24/13 10:29 AM Attachment (5 downloads)

Joe,
If you have a C-8 that has the plug for the power cord on the bottom of the mount, it is using the Belden oval shaped cord. Both the cord and the plug on the base are the three wire types with the center pin grounded. So your scope is ground IF you plug it into a grounded outlet in your house and you use a three wire Belden power cord. I'm pretty sure your C-8 is the type with the oval grounded plug located on the bottom of the base.
When Celestron first introduced the orange model units, they did not use the Belden cord and oval plug on the bottom of the base. Instead the receptacle for the power cord was location on the side of the base of the mount and not on the bottom. The type of plug they used were Cinch Jones type.
Here is a picture of the power cord I made for my old C-8 that has the Jones plug and shows what the plugs look like. The Jones plug has only two prongs, so no ground prong. So if you have this type of mount and the original power cord then the base is NOT grounded
If you look at the end of my cord were the Jones plug is attached you can see the Green ground wire coming out. I attached it to metal frame of the plug. To have the telescope grounded I would need to attach a wire to the mount and then attach it to the green ground wire AND be sure to plug the cord into outlet that is grounded.

- Dave


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Re: C8 Grounding question new [Re: DAVIDG]
      #6155241 - 10/24/13 10:42 AM

His C8 is not a Sand Cast mount Dave. He has 2 C8s.
Both are the oval cord series.

Edited by orion61 (10/24/13 10:44 AM)


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Re: C8 Grounding question new [Re: orion61]
      #6155353 - 10/24/13 11:42 AM

Quote:

His C8 is not a Sand Cast mount Dave. He has 2 C8s.
Both are the oval cord series.




If that is the case, then the mount should be grounded. To test that it is, plug the power cord into the base of C-8 and test the resistance from the center ground pin on the plug on the power cord to some bare metal on the base of the mount of the C-8. The resistance should be be very low.

- Dave


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Re: C8 Grounding question new [Re: DAVIDG]
      #6155670 - 10/24/13 02:24 PM

Quote:

His C8 is not a Sand Cast mount Dave. He has 2 C8s. Both are the oval cord series.




Larry, my other guardian angel! Exactly correct.

So, my C8s were grounded all along! Nice to know my fears were ungrounded. No wasted effort, though; this is the sort of information that should be found on these forums. Maybe I'm not the only dazed, confused astronomer who thought his Orange Tubes were not up to modern safety standards. Someone else will need to know. Besides, I now know to always supply my own GCFI when using unfamiliar outlets at viewing sites. Then even if it's not grounded, that's a good safeguard.

Testing the ground sounds like a job for an electrical meter, which I don't have, but may soon. I have a habit of buying whatever tools I need, because I always need them again once I know how to use them.

Thousand thanks,

Joe


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Re: C8 Grounding question new [Re: Joe Cepleur]
      #6155681 - 10/24/13 02:32 PM

This arrived in a private message:

Quote:

The post-sand cast C8s have the 3 conductor cord which includes a ground pin so they should be OK. But I seem to recall a post where someone found the ground wire was not connected internally in the base of the scope, so that's really not good.




I also have a vague memory of such a thread, which may be the origin of my concerns. Sounds as though Dave's test for the grounding is indeed in order, so I'll find an electrical tester.


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Re: C8 Grounding question new [Re: Joe Cepleur]
      #6155713 - 10/24/13 02:53 PM Attachment (5 downloads)

Quote:

This arrived in a private message:

Quote:

The post-sand cast C8s have the 3 conductor cord which includes a ground pin so they should be OK. But I seem to recall a post where someone found the ground wire was not connected internally in the base of the scope, so that's really not good.




I also have a vague memory of such a thread, which may be the origin of my concerns. Sounds as though Dave's test for the grounding is indeed in order, so I'll find an electrical tester.




It is correct that there is no ground wire from the center pin on the oval plug connecting to the telescope BUT the ground pin is attached to a metal band. That Band is attached to the metal housing of the plug and the metal housing is screwed to the bare metal base of the telescope. See the attached picture. So in theory the ground pin IS electrically in contact with the telescope base and grounding it. BUT you need to test the resistance from the grounding pin on the CORD when the cord is plugged into the telescope to the bare metal base to be sure that the resistance is very low. You can have a break in the wire in the cord or poor electrical connect between the metal housing of the plug in the base to the base of the telescope.

- Dave


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Re: C8 Grounding question new [Re: DAVIDG]
      #6155756 - 10/24/13 03:17 PM Attachment (5 downloads)

Here's the Belden #17280 cord for my ca. 1983-84 Super C8. I ordered it from Hands-On Optics. The scope has a Byers drive, and I've never opened it to see if the ground circuit inside is intact. Neither have I been electrocuted...

...yet.

Belden #17952 will also work, but polarity is reversed.

Edited by ColoHank (10/24/13 03:19 PM)


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Re: C8 Grounding question new [Re: DAVIDG]
      #6156490 - 10/24/13 10:26 PM Attachment (4 downloads)

Cannot stress what Dave is saying enough. Any C-8, or any other telescope, that does not have a three prong plug needs modification. If you like to breathe anyways.

Edited by greju (10/25/13 11:59 AM)


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Re: C8 Grounding question new [Re: ColoHank]
      #6157112 - 10/25/13 10:03 AM

So, a modern plug would have a wire running from the ground pin, fastened to something sure, such as the motor. The Belden's ground plug essentially touches its own metal case, which touches the telescope's base, and so should conduct power from the motor if shorted. A lot of "shoulds" there. This must be part of why the Belden became obsolete. Certainly would not work in a plastic housing!

Given the lack of deaths from electrocution with old C8s, the system must work pretty well, but I still want to test mine. Sounds easy enough to fix if the grounds are not working.

That cord with reversed polarity must be for the Southern Hemisphere!


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Re: C8 Grounding question new [Re: Joe Cepleur]
      #6157245 - 10/25/13 11:19 AM

Quote:

That cord with reversed polarity must be for the Southern Hemisphere!.




Yes so the scope goes in the opposite direction!

Regards Norm


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Re: C8 Grounding question new [Re: Joe Cepleur]
      #6157278 - 10/25/13 11:39 AM

Hi Joe,
The Belden male plug is well engineered. It's design made sure that there was always an electrical connection between the metal housing of the plug to the ground pin. The plug also provided a solder point were one could attach a grounding wire if needed. So it was designed to be safe in itself as a unit. It was up to the designer of the device it was used in to be sure that the correct electrical ground was used with the plug. In the case of Celestron, they understood that the plug would be installed in the bare metal base of the scope using metal screws. This would provide the electrical path from the grounding pin to the housing of the telescope, so this is why they didn't use any addition grounding wire. In 99% of time this will work well for grounding the scope. Also remember that your mount is well painted offering some addition protection. If the housing is plastic as with many power hand tools, the plastic body can provide total electrical isolation making it very safe. So plastic body telescope mounts if designed correctly can also be very safe electrically.
Personally, I believe the danger is not from an electrical short in the telescope but from the condition of the extension cord used, running the cord over wet ground and failing to plug the telescope into at least a grounded outlet if not one that is protected by a GFI.

- Dave


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DAVIDG
Post Laureate
*****

Reged: 12/02/04

Loc: Hockessin, De
Re: C8 Grounding question new [Re: Norm Meyer]
      #6157292 - 10/25/13 11:49 AM

Quote:

Quote:

That cord with reversed polarity must be for the Southern Hemisphere!.




Yes so the scope goes in the opposite direction!

Regards Norm




Nope, reversing the polarity on a AC syn motor doesn't make it go backwards.
The Belden cord that has the reserve polarity was designed for device that used a "hot case". Vintage radio something were wired this way. Reversing the polarity, connected the case to neutral vs hot and made it safer.
In the case of a Celestron, it doesn't matter because the winding in the motor is electrically isolated so no part of the motor housing under normal conditions is electrical energized.

- Dave


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: C8 Grounding question new [Re: DAVIDG]
      #6157309 - 10/25/13 12:01 PM

Quote:

Personally, I believe the danger is not from an electrical short in the telescope but from the condition of the extension cord used, running the cord over wet ground and failing to plug the telescope into at least a grounded outlet if not one that is protected by a GFI.




I can vouch for that, without being an electrical wizard! Here in the Frozen North, telescopes run all winter. When the temperature rises above freezing, extension cords can run through puddles if one is not careful. I, personally, will only use cords in perfect repair, and never those from which some cowboy has removed the grounding plug.

I had not realized paint was so protective against electrical shock. Amazing!


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roscoe
curmudgeon
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Reged: 02/04/09

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Re: C8 Grounding question new [Re: Joe Cepleur]
      #6158074 - 10/25/13 07:33 PM

A 3-prong isn't the only way to go... if you look at most semi-modern 2-prong plugs, one side is wider than the other. This prevents them from being plugged in backwards, as a safety system. the wider prong is connected to the white/neutral/grounded side of the electrical service(fuse or breaker panel), unless of course some red-eye kill-a-watt wired the outlet wrong, which, of course, can happen with 3-prong outlets, too.
This 2-prong system insures that, for a lamp as an example, the threaded part the bulb screws into is neutral - and not switched, and only the little tab in the bottom is 'hot' and only with the switch on.
Best overall insurance?? Buy an outlet tester! They are the size of an ice cube, have a 3-prong plug on one end and 3 neon lights on the other end. $5-7 at any big-box or decent hardware store. two green...all ok. Anything else.... DANGER!
R


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Joe Cepleur
Carpal Tunnel


Reged: 03/18/10

Loc: Dark North Woods
Re: C8 Grounding question new [Re: roscoe]
      #6158957 - 10/26/13 11:12 AM

I have an outlet tester. Great gizmo.

Is a properly wired two-prong, flanged outlet as safe as a three-prong? My house is older and has lots of two-prong outlets. I thought they were not grounded, and so were inherently less safe. Interesting, though, to learn how a properly wired two-prong protects against easily touching the hot wire.

To run my scope in the back yard, I run a long extension to a three-prong, known-good, grounded outlet.


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roscoe
curmudgeon
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Reged: 02/04/09

Loc: NW Mass, inches from VT
Re: C8 Grounding question new [Re: Joe Cepleur]
      #6160283 - 10/27/13 07:48 AM

First, a disclaimer: I am not a licensed master electrician. The information I'm sharing is based on training by an actual electrician, but even if I was licensed, I could only know for sure how anyone's house was wired by going there. making a couple of tests, and opening up the power panel to see how it's wired, and also be totally familiar with your state's electrical codes, so I'd know what to expect.
And, be completely totally positively sure the circuit's power is turned off at the power panel BEFORE you start sticking the screwdriver in there.....

All that aside, most states (but not all) require that the white/neutral wire in a cable be connected to a grounded, terminal strip, as well as the bare copper (or green insulated) wire also in the cable. (grounded, as in....connected with a fat wire to long metal rods pounded into the ground, or a buried metal water pipe)

Older metal-jacketed wire normally only had/has 2 wires in it (white and black) and the metal wrapping is a fair, but not as good as copper wire, ground system. It is connected to the power panel with clamps that secure it, but in an older, somewhat corroded box, this connection can be somewhat vague.

The intermediate step was to switch to 3-wire plastic jacketed cable, (blk, wht, gnd) and usually connect the ground to the terminal strip in the panel (note I said usually...) and the ground wire is wrapped around the insulation at the outlet end, just behind the end of the exposed wires, and clamped in the wire clamp on the back or end of the metal wall box. Better, but not as good as a direct connection to the outlet.
Sometimes, it is possible to cut a small hole in the wall immediately beside the box where the wire enters, loosen the clamp nut, turn it so the clamp screws can be accessed thru the hole, loosen the screws, and pull the wire into the box enough to get to the end of that wire and unwrap it, then it is available for real outlet grounding, assuming that is really grounded at the panel, that is.....
If all is well, you can install a 3-prong outlet and have a good ground available for use. (white on the silver-screw side, black on the gold/brass side....., ground wire on the green screw )
So...sometimes it is possible to upgrade to 3-prongs in an existing box, but that also depends on how many other junction boxes there were on the way back to the panel, and how the grounds were treated in these boxes. You can open the covers and look..... The rules for a longtime have specified 'no buried boxes' but renovations happen.....

Nowadays, good ground connections right to the outlets are the rule, if your house came with 3-prongs everywhere, you should be completely fine. The outlet tester will tell you.

As to 2-prong polarized or 3-prong..... mostly, 3-prong is installed on stuff with metal cases, so as to be sure that no matter what happens, the outside is not going to be 'hot'. 2-prong is pretty safe, not only table lamps and the like are 2-prong, but even expensive home appliances - vacuum cleaners, food mixers, that sort of stuff, and most power tools, are wired that way. If there were safety issues, legal costs would have put 3-prongs on by now.

The situation changes, though, with old stuff. The insulation on the wires inside the item can get old and brittle and crumbly and then a wire can touch against the outside of the item. This is not uncommon in vintage lighting, for instance.

Mostly, you need to open older stuff up and look, and if the wiring is cracking and crumbly. particularly right as it comes out of a component like a motor, bad things can happen. In a plastic case, you're probably ok, if something happens and the wires touch, there'll be a flash, that part of the wires will vaporize, and the circuit breaker will pop.

I think, for safety's sake though, that a component with a metal case used outdoors be converted to a 3-prong, with the green wire bolted right to the metal case. Yes, I know it's not TRULY vintage, but neither is re-finishing a tripod (even with penetrating oils, which aren't original-issue) or getting a mirror recoated....
Computer cords, which seem to accumulate rapidly nowadays, are good sources of 3-prong wires, but they have a different color coding on the inner wires that I have not memorized yet, and 3-prong extension cords with the 3-hole end cut off work well, too, and avoid the big clunky bolt-it-on-yourself plug ends.

Hope all that made some sense...........
Russ


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kansas skies
sage


Reged: 12/02/12

Loc: Kansas, USA
Re: C8 Grounding question new [Re: roscoe]
      #6160881 - 10/27/13 02:36 PM

I've been reading back through this thread and would like to reiterate that which I stated before - simply grounding the exposed metal housing of equipment you're using does not necessarily create a safe environment. Obviously, this would be a good idea if a hot wire inside that particular piece of equipment were to come in contact with the case, as might happen with a frayed wire or a loose connection. The end result here would hopefully be a blown fuse or a popped circuit breaker. The real danger comes other equipment being used. If the other equipment has voltage exposed to the outside world for whatever reason, the large grounded object (telescope housing) will become an excellent return path for that voltage. If this exposed voltage directly contacts the grounded telescope housing, hopefully a fuse blows or a circuit breaker pops. However, if the person using the equipment manages to bridge the gap between the two, a nasty shock may result. A case in point might be the electric guitar player using a faulty guitar amp that manages to get electrocuted when his lips come in contact with a grounded microphone. A GFI should offer protection in this scenario as it designed to disconnect a circuit when it senses a difference in the amount of current flowing between the hot wire and the neutral wire within that circuit.

I noticed a couple of statements concerning safety that I found interesting. One was that this person never heard of anyone being electrocuted by a C8. I don't know of any either, but I guess there could always be a first. What I get from this is that if the equipment is properly maintained, it has proven to be a safe and reliable appliance. However, as much of this equipment is fast approaching middle age, proper maintenance is a must. It's my opinion that this properly maintained equipment is as safe as it was when new, therefore, I don't take any special precautions beyond proper maintenance and feel perfectly safe.

The other statement stated that a battery pack is just a dangerous as a line supply. While it is true that the level of current may be the same within a circuit being powered by either, a level of safety with the battery powered circuit is implied due to it being isolated from line current (which is referenced to earth ground). The battery powered equipment, if not tied directly to earth ground, is allowed to float. For this reason, sources of external voltage potential (including earth ground) become less problematic.

Bill


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Live_Steam_Mad
sage


Reged: 07/24/07

Loc: Moss Bank, St.Helens, England
Re: C8 Grounding question new [Re: kansas skies]
      #6268979 - 12/23/13 04:34 PM

Is it possible to convert a vintage orange tube C8 from AC only over to DC operation by changing out the AC motors to some DC motor / gearbox substitute? Anyone done it before?

I would like an orange tube C8 at some point but I don't want to get a 240V shock from it if something ever goes wrong since in England UK we are on 240V.

BTW did the orange tube C8's imported into England get fitted with 240 to 120V converters, or instead 240 Volt motors, i.e. how was the orange C8 made to run on our 240V supply?

Also our supply is at a different frequency (we are on 50Hz versus 60Hz).

Best Regards,

Alistair G.

Edited by Live_Steam_Mad (12/23/13 04:35 PM)


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