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-   -   Main circuit breaker's screws hot even with breaker off? (http://www.diychatroom.com/f18/main-circuit-breakers-screws-hot-even-breaker-off-129942/)

darlingm 01-14-2012 01:23 PM

Main circuit breaker's screws hot even with breaker off?
 
My panel looked like a hairball that a cat threw up, so I rewired it the other day. Labeled the hot wires with their circuit numbers on masking tape, unscrewed everything, and put it all back in an organized manner. Replaced a few breakers that were a different manufacturer than the panel while I was at it.

My system has a main breaker and no disconnect outside at the meter. I knew turning off the main would only turn off power to the hot bus bars, that the line coming in would still be hot.

I treated the screws on the main breaker the whole time as if they were hot, being extremely careful not to let anything touch them. Went fine, had no problems. (Was also wearing rubber soled shoes standing on a rubber mat, and took my ring off.)


Did I need to do this, or are main breakers made so that their screws just clamp down the wire internally but aren't hot themselves? I could so easily see a wire slipping and hitting one of those screws if someone isn't overly paranoid about them.

Seems to me like there's no benefit of having the screw itself hot, and that they could/should engineer at least the main so it wouldn't be.

gregzoll 01-14-2012 01:26 PM

Hope your life insurance policy is paid for. This is a good post of what is wrong in so many ways, when working in a live panel.

darlingm 01-14-2012 01:28 PM

Quote:

Originally Posted by gregzoll (Post 822446)
Hope your life insurance policy is paid for. This is a good post of what is wrong in so many ways, when working in a live panel.

Boy, if I screwed up, I'm glad I made it through it. I'd love to know what I did wrong, though.

gregzoll 01-14-2012 01:35 PM

Working on a hot panel, without pulling the meter.

darlingm 01-14-2012 01:40 PM

Quote:

Originally Posted by gregzoll (Post 822454)
Working on a hot panel, without pulling the meter.

I'm confused. I really thought that when replacing breakers or adding new circuits that turning off the main did the trick, without having the meter pulled -- as long as you aren't re-wiring the main or doing anything with the wires going to the meter.

EDIT: So many guides that I've seen say when working with circuits, you have to turn main off or have meter pulled, but not both.

jproffer 01-14-2012 01:47 PM

Any time there is a chance, however remote it may be, of touching one of the hot conductors coming in or (as you asked about) the screws holding them in, it's a good idea to disconnect the next place upstream from that.

Or a more general rule...

Any time there is a chance, however remote it may be, of touching whatever you're working on, it's a good idea to disconnect the next place upstream from that.


You got lucky. I've done it too so I won't jump ya too bad...but I shouldn't have. And you shouldn't have either.

You lived through it, so all is well....but next time.... :thumbsup:


BTW, before 100 people disagree with me :) :

If I was pulling in a new circuit or just moving one or two things...I wouldn't mess with the meter. If I had a "hairball that a cat threw up" and I was re-sorting everything...have it pulled.

TarheelTerp 01-14-2012 01:56 PM

"hairball that a cat threw up"

this will be a technical term soon

jbfan 01-14-2012 03:54 PM

A homeowner should never, ever, never pull the meter!
Taking of the ring was a good step, but the mat and shoes had no effect.

joed 01-14-2012 05:24 PM

Quote:

Originally Posted by jbfan (Post 822574)
A homeowner should never, ever, never pull the meter!
Taking of the ring was a good step, but the mat and shoes had no effect.

Agree. You did it correct in my opinion. In Canada the main breaker is in a separate section with its own cover. Turn off the main and everything you see is safe.
As long as you stay clear of the main supply lines coming into the main breaker you are safe.

mpoulton 01-14-2012 06:22 PM

I would say your method (main off, meter in) is perfectly acceptable and is the standard approach. The screws on the line side of the main breaker are hot, they are not isolated.

In a commercial setting, working in a panel with any accessible hot parts (no matter how small) is subject to NFPA 70E rules for hot work, resulting in extremely burdensome personal protective equipment requirements... which almost nobody actually complies with in circumstances like this.

jlmran 01-14-2012 10:50 PM

Quote:

Originally Posted by jbfan
A homeowner should never, ever, never pull the meter!

Is this a safety statement or a legal/trespassing statement?

Julius793 01-15-2012 01:14 AM

Quote:

Originally Posted by jlmran

Is this a safety statement or a legal/trespassing statement?

Can be both, depending on your poco

frenchelectrican 01-15-2012 02:11 AM

Quote:

Originally Posted by jlmran (Post 822887)
Is this a safety statement or a legal/trespassing statement?

Quote:

Originally Posted by Julius793 (Post 822951)
Can be both, depending on your poco

Very simple .,, Both!!

I have allready survied couple meter blow up on me when when I did try to remove it ( I do used the specail tool for this ) and that why I do not want any homeowner to remove the meter at all for safety reason and many POCO will throw a fit when you remove it espcally with new smart meter they will send a signal when the meter is removed.

So for safety sake S.V.P Do not remove the meter yourself and everything from the main breaker to the POCO lines are unfused secondary and if something short out it will run like runaway welder until the cable burn out or transfomer give up smoke or cutout kicked out.

Merci,
Marc

Stubbie 01-15-2012 11:44 AM

You as a homeowner never remove the meter. As an electrician on service call you don't remove the meter. You turn the main off whether it is remote or internal to the panel. You do have certain safety equipment/ clothing that is standard SOP.
What you did is perfectly acceptable, though possibly not advisable based on your knowledge. There are also guards that can be placed over the mains, it just depends.
There are many things that can be wrong in a panel that are life threatning, specifically current from an outside source on your grounding electrode system or a failed grounded (neutral conductor) of the utility and your grounding system making up for it. The later not so dangerous once the main is opened.
So there are several things to check before working, proper bonding for the situation and configuration of the service entrance and objectionable current for the most part.


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