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Equipment Discussions >> Classic Telescopes

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actionhac
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Reged: 08/09/08

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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Reged: 11/06/12

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.
Carpal Tunnel
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Reged: 10/01/08

Loc: Upstate NY
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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Reged: 11/06/12

Loc: South Carolina
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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Reged: 07/06/07

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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Reged: 07/06/07

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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Reged: 08/09/08

Loc: Seattle
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
sage


Reged: 12/02/12

Loc: Kansas, USA
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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Reged: 12/02/04

Loc: Hockessin, De
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
scholastic sledgehammer
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Reged: 11/06/12

Loc: South Carolina
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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Reged: 07/06/07

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
scholastic sledgehammer
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Reged: 11/06/12

Loc: South Carolina
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
Carpal Tunnel
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Reged: 10/14/09

Loc: North Carolina
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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DAVIDG
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Reged: 12/02/04

Loc: Hockessin, De
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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dgreyson
scholastic sledgehammer
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Reged: 11/06/12

Loc: South Carolina
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
sage


Reged: 12/02/12

Loc: Kansas, USA
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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rmollise
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Reged: 07/06/07

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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rmollise
Postmaster
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Reged: 07/06/07

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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actionhac
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Reged: 08/09/08

Loc: Seattle
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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orion61

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Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: C8 Grounding question [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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