orion61
Vendor(Clear Edge Optical)
   
Reged: 10/20/07
Loc: NW Iowa BURRRR
|
C8 Grounding question
#5606092 - 01/05/13 07:58 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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?
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: orion61]
#5606314 - 01/05/13 10:57 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
Notice: this does not constitute qualified advice and should be considered as hearsay and rumour. your mileage may vary. This product is meant for educational purposes only. Any resemblance to real persons, living or dead is purely coincidental. Void where prohibited. Some assembly required. List each check separately by bank number. Batteries not included. Contents may settle during shipment. Use only as directed. No other warranty expressed or implied. Do not use while operating a motor vehicle or heavy equipment. Postage will be paid by addressee. Subject to approval. This is not an offer to sell securities. Apply only to affected area. May be too intense for some viewers. Do not stamp. Use other side for additional listings. For recreational use only. Do not disturb. All models over 18 years of age. If condition persists, consult your physician. No user-serviceable parts inside. Freshest if eaten before date on carton. Subject to change without notice. Times are approximate. Simulated picture. No postage necessary if mailed in the United States. Breaking seal constitutes acceptance of agreement. For off-road use only. As seen on TV. One size fits all. Many suitcases look alike. Contains a substantial amount of non-tobacco ingredients. Colors may, in time, fade. We have sent the forms which seem to be right for you. Slippery when wet. For office use only. Not affiliated with the American Red Cross. Drop in any mailbox. Edited for television. Keep cool; process promptly. Post office will not deliver without postage. List was current at time of printing. Return to sender, no forwarding order on file, unable to forward. Not responsible for direct, indirect, incidental or consequential damages resulting from any defect, error or failure to perform. At participating locations only. Not the Beatles. Penalty for private use. See label for sequence. Substantial penalty for early withdrawal. Do not write below this line. Falling rock. Lost ticket pays maximum rate. Your cancelled check is your receipt. Add toner. Place stamp here. Avoid contact with skin. Sanitized for your protection. Be sure each item is properly endorsed. Sign here without admitting guilt. Slightly higher west of the Mississippi. Employees and their families are not eligible. Beware of dog. Contestants have been briefed on some questions before the show. Limited time offer, call now to insure prompt delivery. You must be present to win. No passes accepted for this engagement. No purchase necessary. Processed at location stamped in code at top of carton. Shading within a garment may occur. Use only in well-ventilated area. Keep away from fire or flame. Replace with same type. Approved for veterans. Booths for two or more. Check here if tax deductible. Some equipment shown is optional. Price does not include taxes. No Canadian coins. Not recommended for children. Prerecorded for this time zone. Reproduction strictly prohibited. No solicitors. No alcohol, dogs, or horses. No anchovies unless otherwise specified. Restaurant package, not for resale. List at least two alternate dates. First pull up, then pull down. Call toll free before digging. Driver does not carry cash. Some of the trademarks mentioned in this product appear for identification purposes only. Record additional transactions on back of previous stub. Decision of judges is final.
This supersedes all previous disclaimer notices.
|
apfever
Carpal Tunnel
   
Reged: 05/13/08
Loc: Colorado
|
Re: C8 Grounding question
[Re: dgreyson]
#5606438 - 01/05/13 11:56 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
nice disclaimer. No comment.
|
desertrefugee
Carpal Tunnel
   
Reged: 08/06/07
Loc: Arizona
|
Re: C8 Grounding question
[Re: apfever]
#5606823 - 01/05/13 03:21 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
"Not the Beatles" !??
Then forget it.
|
Littlegreenman
Carpal Tunnel
   
Reged: 05/09/05
Loc: Southern California
|
Re: C8 Grounding question
[Re: desertrefugee]
#5606945 - 01/05/13 04:44 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Maybe someone knows if running it offer a battery pack reduces any shock or electrocution risk?
Disclaimer This posts has no disclaimers.
LGM
|
desertrefugee
Carpal Tunnel
   
Reged: 08/06/07
Loc: Arizona
|
Re: C8 Grounding question
[Re: Littlegreenman]
#5607041 - 01/05/13 05:56 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
orion61
Vendor(Clear Edge Optical)
   
Reged: 10/20/07
Loc: NW Iowa BURRRR
|
Re: C8 Grounding question
[Re: desertrefugee]
#5607066 - 01/05/13 06:06 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: orion61]
#5607129 - 01/05/13 06:36 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
Littlegreenman
Carpal Tunnel
   
Reged: 05/09/05
Loc: Southern California
|
Re: C8 Grounding question
[Re: desertrefugee]
#5607202 - 01/05/13 07:50 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: Littlegreenman]
#5607276 - 01/05/13 08:50 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
[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.
|
orion61
Vendor(Clear Edge Optical)
   
Reged: 10/20/07
Loc: NW Iowa BURRRR
|
Re: C8 Grounding question
[Re: dgreyson]
#5607302 - 01/05/13 09:06 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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...
|
johntrob
sage
   
Reged: 03/14/11
Loc: Georgia, USA
|
Re: C8 Grounding question
[Re: orion61]
#5607377 - 01/05/13 10:05 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Remember the old refrigerators, grab the handle and get a charge, still alive.
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: johntrob]
#5607581 - 01/06/13 12:00 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: orion61]
#5607590 - 01/06/13 12:03 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
actionhac
Post Laureate
   
Reged: 08/09/08
Loc: WA
|
Re: C8 Grounding question
[Re: dgreyson]
#5607640 - 01/06/13 12:48 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
DAVIDG
Post Laureate
   
Reged: 12/02/04
Loc: Hockessin, De
|
Re: C8 Grounding question
[Re: actionhac]
#5608157 - 01/06/13 11:41 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
tim53
Postmaster
   
Reged: 12/17/04
Loc: Highland Park, CA
|
Re: C8 Grounding question
[Re: orion61]
#5608308 - 01/06/13 12:56 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
PiSigma
Carpal Tunnel
   
Reged: 10/14/09
Loc: North Carolina
|
Re: C8 Grounding question
[Re: DAVIDG]
#5608316 - 01/06/13 12:58 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
tim53
Postmaster
   
Reged: 12/17/04
Loc: Highland Park, CA
|
Re: C8 Grounding question
[Re: tim53]
#5608340 - 01/06/13 01:08 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
orion61
Vendor(Clear Edge Optical)
   
Reged: 10/20/07
Loc: NW Iowa BURRRR
|
Re: C8 Grounding question
[Re: PiSigma]
#5608350 - 01/06/13 01:14 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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..
|
actionhac
Post Laureate
   
Reged: 08/09/08
Loc: WA
|
Re: C8 Grounding question
[Re: orion61]
#5608752 - 01/06/13 04:22 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: actionhac]
#5609826 - 01/07/13 09:43 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
Geo.
Carpal Tunnel
   
Reged: 10/01/08
Loc: Upstate NY
|
Re: C8 Grounding question
[Re: dgreyson]
#5612366 - 01/08/13 05:30 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: Geo.]
#5612634 - 01/08/13 08:14 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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"
|
rmollise
Postmaster
   
Reged: 07/06/07
|
Re: C8 Grounding question
[Re: DAVIDG]
#5613360 - 01/09/13 09:17 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
rmollise
Postmaster
   
Reged: 07/06/07
|
Re: C8 Grounding question
[Re: Littlegreenman]
#5613366 - 01/09/13 09:19 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
actionhac
Post Laureate
   
Reged: 08/09/08
Loc: WA
|
Re: C8 Grounding question
[Re: rmollise]
#5613567 - 01/09/13 11:45 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
kansas skies
sage
Reged: 12/02/12
Loc: Kansas, USA
|
Re: C8 Grounding question
[Re: actionhac]
#5613712 - 01/09/13 01:14 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
DAVIDG
Post Laureate
   
Reged: 12/02/04
Loc: Hockessin, De
|
Re: C8 Grounding question
[Re: kansas skies]
#5613729 - 01/09/13 01:29 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: rmollise]
#5613774 - 01/09/13 01:55 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
rmollise
Postmaster
   
Reged: 07/06/07
|
Re: C8 Grounding question
[Re: dgreyson]
#5613810 - 01/09/13 02:19 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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..
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: rmollise]
#5613870 - 01/09/13 02:58 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
PiSigma
Carpal Tunnel
   
Reged: 10/14/09
Loc: North Carolina
|
Re: C8 Grounding question
[Re: DAVIDG]
#5613913 - 01/09/13 03:17 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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?
|
DAVIDG
Post Laureate
   
Reged: 12/02/04
Loc: Hockessin, De
|
Re: C8 Grounding question
[Re: dgreyson]
#5613979 - 01/09/13 04:04 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: DAVIDG]
#5614010 - 01/09/13 04:18 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
kansas skies
sage
Reged: 12/02/12
Loc: Kansas, USA
|
Re: C8 Grounding question
[Re: dgreyson]
#5614157 - 01/09/13 05:46 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Maybe it's just me, but I worry more about tripping over the extension cord than getting shocked or electrocuted.
Bill
|
rmollise
Postmaster
   
Reged: 07/06/07
|
Re: C8 Grounding question
[Re: dgreyson]
#5614231 - 01/09/13 06:27 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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!
|
rmollise
Postmaster
   
Reged: 07/06/07
|
Re: C8 Grounding question
[Re: dgreyson]
#5614239 - 01/09/13 06:31 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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!
|
actionhac
Post Laureate
   
Reged: 08/09/08
Loc: WA
|
Re: C8 Grounding question
[Re: rmollise]
#5614277 - 01/09/13 06:48 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
orion61
Vendor(Clear Edge Optical)
   
Reged: 10/20/07
Loc: NW Iowa BURRRR
|
Re: C8 Grounding question
[Re: actionhac]
#5614436 - 01/09/13 08:10 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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..
|
BRisley
Carpal Tunnel
   
Reged: 09/04/06
Loc: SW Florida
|
Re: C8 Grounding question
[Re: orion61]
#5614681 - 01/09/13 11:10 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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
|
Geo.
Carpal Tunnel
   
Reged: 10/01/08
Loc: Upstate NY
|
Re: C8 Grounding question
[Re: orion61]
#5614760 - 01/10/13 12:22 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
RLTYS
Post Laureate
   
Reged: 12/18/04
Loc: New York (Long Island)
|
Re: C8 Grounding question
[Re: BRisley]
#5615402 - 01/10/13 12:11 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Brians right lets keep this thread on subject.
Rich (RLTYS)
|
Joe Cepleur
Pooh-Bah
Reged: 03/18/10
Loc: Dark North Woods
|
Re: C8 Grounding question
[Re: RLTYS]
#5626008 - 01/16/13 11:10 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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)
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: Joe Cepleur]
#5626113 - 01/16/13 12:33 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
Joe Cepleur
Pooh-Bah
Reged: 03/18/10
Loc: Dark North Woods
|
Re: C8 Grounding question
[Re: dgreyson]
#5626235 - 01/16/13 01:48 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: Joe Cepleur]
#5626290 - 01/16/13 02:23 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
Joe Cepleur
Pooh-Bah
Reged: 03/18/10
Loc: Dark North Woods
|
Re: C8 Grounding question
[Re: dgreyson]
#5626339 - 01/16/13 02:56 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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!
|
dgreyson
sage
   
Reged: 11/06/12
Loc: South Carolina
|
Re: C8 Grounding question
[Re: Joe Cepleur]
#5626421 - 01/16/13 03:42 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
Joe Cepleur
Pooh-Bah
Reged: 03/18/10
Loc: Dark North Woods
|
Re: C8 Grounding question
[Re: dgreyson]
#5683072 - 02/16/13 09:44 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
apfever
Carpal Tunnel
   
Reged: 05/13/08
Loc: Colorado
|
Re: C8 Grounding question
[Re: Joe Cepleur]
#5683123 - 02/16/13 10:09 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|
Joe Cepleur
Pooh-Bah
Reged: 03/18/10
Loc: Dark North Woods
|
Re: C8 Grounding question
[Re: apfever]
#5683331 - 02/16/13 11:48 AM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
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.
|