I found it!! Grounding on a centertapped transformer.

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cschmid said:
drag heck barbecue thick and juicy steaks and deliciously season ground steak..:grin:
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And your medium rare comment was dead on. If I wanted a chew toy, I could borrow one from my best friend.
 
quogueelectric said:
I had spoken out at one time that a transformer was centertapped and grounded to keep the voltages to ground at a safer level and was jumped on like a pack of wolves that this was untrue ... the book that it is referenced in is the OSHA Standards for the construction Industry (29 CFR PART 1926) With Amendments as of January 2006. ... This is an electrical safety requirement handed down from the federal government and it is also the law. ...
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No question in my mind that OSHA requires it. No question that th NEC requires it - None - Zero

I only question that the grounding promotes any personel safety.

This isn't jumping on you - I absolutely agree the law requires the grounding as you, OSHA, and the NEC say.

I just can't find any science that particularly supports the grounding adds any safety.

carl
 
coulter said:
No question in my mind that OSHA requires it. No question that th NEC requires it - None - Zero

I only question that the grounding promotes any personel safety.

This isn't jumping on you - I absolutely agree the law requires the grounding as you, OSHA, and the NEC say.

I just can't find any science that particularly supports the grounding adds any safety.

carl
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Like the art of war keep your friends close and your enemys closer. When things are grounded you know where it is coming from. If you understand theory correctly it is very safe. If you are a bumbling buffoon who doesnt clearly understand what it is you are working on you almost deserve it not that I wish any harm to anybodybut somewhere somehow someone must take accountability for thier actions. With the recent wave of OSHA awareness you couldnt get hurt if you tried yet who is going to pay for all of this?????
 
coulter said:
I only question that the grounding promotes any personel safety.
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If a person comes into contact with a line conductor and an equipment enclosure, I am sure that person would prefer a 120v shock over a 240v shock. Without a centertap bond/ground, there exists the possibility of a 240v shock to the enclosure. With the centertap bond/ground, that possibility is highly unlikely.

We could come up with plenty of shock scenarios/body resistances where the 240 volt shock could be fatal but the 120 volt shock may not kill. On the other hand, I am not an electrocution expert, so I may not have a clue.
 
crossman said:
...I am sure that person would prefer a 120v shock over a 240v shock...
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medium rare vs well-done? A regular smorgasbord of near-death experiences...which one do I want, which one do I want?...last week was the finger-to-switchbox...humm, Hey Joe!, which one are you having?
Joe: none for me, thanks, I'm trying to cut back. :smile:
 
I like mine just on the sizzling side so hit off with a 2X4 just after the surface changes color..Now that is not right..:rolleyes:

One could argue that the center tap increase safety but yet I believe it is really only a voltage stabilization method..
 
cschmid said:
One could argue that the center tap increase safety but yet I believe it is really only a voltage stabilization method..
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Grounding any conductor would "stabilize" a system by fixing each conductor's voltage relative to earth. The only additional effect of opting for the neutral would be to minimize those voltage levels, again relative to earth.

A Delta has no point to ground that could result in a lower voltage to earth than another, but we still consider a grounded Delta 'safer' than an ungrounded one, and opt for floating only if we need the advantages. Why is that?

There are benefits and detriments to both. Under 'normal' conditions, the floating system is arguably safer, but under adverse conditions, such as a primary-to-secondary fault, the grounded system is clearly safer for personnel and equipment alike.

It may not have been part of the decision choice (I bet it was), but safety of personnel is clearly within the advantages of a grounded supply system for our work, as well as home use. Plus, GFCI devices require a system ground to function.

I'd rather work around a voltage-to-earth I can predict, and I'm sure we all want our loved ones to face at worst a 120-volt shock hazard in the home, rather than 240 volts, or worse yet, a possible KV-range hazard. People do benefit.
 
Larry, Crossman -
I completely agree the bonding increases safety - which I think addresses the suitations you are discussing.

Well, except for one bond. Most utility 1ph transformers have the high side neutral connected to case ground. Also, the low side Center Tap is connected top the same case ground. I think this band causes a lot of problems and has no advantage to the homeowner

carl
 
not the one that hit the ground, rather ground steak is the one that was hit repeatedly with the cow hammer..:grin:

I wonder how the European electrical hazards safety statistics are compared to the United States statistics..

I believe the Delta transformer is a design standard use in critical operations due to the fact you can loose a winding and still use the transformer at full voltage..

The Delta transformer costs much more money than a Y transformer and the POCO charges more for it use. Which makes it less desirable in allot of installations..

Grounding makes it appear more safe but if a short circuit occurs to ground the resistance is to high to open circuit that is why it is bonded to the grounded conductor..So over current devices work properly..

Dang it ground again why can I not get my steak ungrounded and done medium rare..:grin: I hope the cow does not have mad cow disease..
 
cschmid said:
...I wonder how the European electrical hazards safety statistics are compared to the United States statistics....
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As I recall (that's code meaning I would have to look it up to be sure), several years ago (10?) The Norwegian system was top, followed by the Germans and then the French, US was below them. Don't know about now.

cschmid said:
...I believe the Delta transformer is a design standard use in critical operations due to the fact you can loose a winding and still use the transformer at full voltage.. ...
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Not that I've ever heard. Preferred system is impedance grounded Wye for critical operations. (Lots of exceptions apply) But realize:
1. Pretty small outfit to have three pots instead of a 3ph unit for a critical operation. So I don't see the one winding failue idea working.
2. Ungrounded systems suffer from restriking, arcing ground faults that can be killers on over voltage to the equipment. One tends to install the system short and well protected.
3. The only time I have used ungrounded D or W (in one case), was because the equipment mfg specified it - oh yeah, the Navy likes for shipboard.

cschmid said:
...The Delta transformer costs much more money than a Y transformer and the POCO charges more for it use. ...
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Are you sure of that. I thought the price of an xfm pretty much went by the pounds of copper and the pounds of steel core - and those are pretty dependent on the KVA. I have never heard that D was inherently more expensive than Y.

The outfits I work for tend to buy their own transformers, so I wouldn't know that the POCO charged more. I'm a little surprised though.

Mostly, I don't think anyone wants to put an ungrounded system outside without surge suppression.

cschmid said:
...Grounding makes it appear more safe ...
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Really - I didn't know that.:D

carl
 
LarryFine said:
...Plus, GFCI devices require a system ground to function...
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They require an alternate path, which you would normally expect to be the ground.
 
mivey said:
They require an alternate path, which you would normally expect to be the ground.
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I mean the supply must be a grounded system. If the supply system has no grounded conductor, a line-to-earth pathway through a person would not be a hazard nor trip a GFCI.
 
LarryFine said:
I mean the supply must be a grounded system. If the supply system has no grounded conductor, a line-to-earth pathway through a person would not be a hazard nor trip a GFCI.
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Wouldn't a line-to-neutral pathway give you the same result (neutral from a different outlet). Or line-to-line for that matter. You might could picture that in an old home with 2-wire romex that has had some GFCI receptacles installed.
 
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