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#61747 - 02/01/06 08:41 PM isolated nuetral in main disconnect?
Clydesdale Offline
Member

Registered: 11/25/04
Posts: 139
i opened a panel today on one of the new houses our company had wired and noticed that someone had removed the jumper for the grounding bar to the neutral bar. the panel is a 200A main breaker. Is this safe to do? I made sure I put all the grounds on the side the grounding electrode conductor was terminated on and all the neutrals on the side the neutral was terminated on....

The reason I am asking is because one of my coworkers was shocked by the range wire's grounded conductor. I was reading 35VAC from nuetral to ground. All breakers were in the tripped position as I had only just installed them. The only breaker that was turned on was for the panel receptacle.

Also...I temporarily fed a pullchain off the panel receptacle breaker, and used the ground bar(isolated) as a neutral...now that I'm thinking about it sounds pretty hazardous. a 100W type A lamp was drawing about .6 Amps. just to see what would happen, i turned off the breaker, and re-installed the groundbar/nuetral jumper, and when I turned the breaker back on, the bulb was burning much brighter, and I read (off the top of my head) roughly .8 Amps of current that the bulb was drawing....

Any and all input please..thank you.

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#61748 - 02/01/06 08:55 PM Re: isolated nuetral in main disconnect?
bot540 Offline
Member

Registered: 09/14/04
Posts: 177
Loc: Vernon Hills, IL
You must install the main bonding jumper. Read article 250.24. Not having this installed could cause all sorts of problems (better explained in the handbook)
_________________________
Jesus may have been a capenter,but God was an electrician.Genesis1:3

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#61749 - 02/02/06 04:00 AM Re: isolated nuetral in main disconnect?
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Assuming that this is the main panel (and not a sub-panel) it is supposed to have the bond in place.

From the description, it does sound as though this is the case. Your temporary lamp was using the grounding bus as the return, inserting the resistance of the grounding system and earth between it and the xfmr neutral. That would account for both the dimmer light and your 35V reading.

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