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#161421 - 04/02/07 10:52 PM main bonding jumper  
triple  Offline
Member
Joined: Apr 2002
Posts: 184
Wisconsin
The code states that the main bonding jumper must be in the first panel or elsewhere on the line side of the service. Where does it say that there cannot be multiple main bonding jumpers for a single service with a single disconnect? For instance, in a residential situation what keeps me from running a grounding electrode conductor up into the meter socket, bonding it there, then runnning it into the main electrical panel where it is again bonded to the grounded conductor. This creates a parallel path between the two enclosures with the grounded and grounding conductors. Wisconsin doesn't allow the main bond to be in a residential meter and the electric utilities don't allow the grounding electrode conductor inside the meter at all (even if it is insulated). However, my question is, does the NEC itself allow this type of parallel path?

Thanks


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#161431 - 04/03/07 12:23 AM Re: main bonding jumper [Re: triple]  
ausador  Offline
Member
Joined: Mar 2007
Posts: 49
Central Florida
No matter where the grounding and grounded conductors are bonded as per your local "flavor" of the code it should still only be in ONE location.

Having worked in several different states I'm sort of used to the seemingly arbitrary administration/interpretation of the NEC in differing localities. Depending on your local code you actually might be required to continue the GEC through the meter grounded connductor bond point and into the main panel to attach to the grounding conductor bar/panel can.

Some locals require the GEC (both rod and water if seperate) to terminate in the meter neutral bonding point. They also forbid a seperate grounding conductor from the meter to the panel. The neutral is the ground for the panel and the bonding jumper installed by the factory must be used to ground the panel and to give the panel grounding bar a path to the GEC.

As I understand it this is to facilitate the the operation of the service surge suppressors required by these locals (frequent lightning strike areas) and to shorten/limit the path of fault current in the event of a lightning strike on the utility side.

I hope this makes sense to you, after thinking about it for a while it finally did to me.....err....sort of...

Irregardless, you should follow what your local AHJ says, they may actually have a reason for it (Usually the local utilities wishes) and even if they don't?...."resistance is futile" (Borg qoute)


#161434 - 04/03/07 02:06 AM Re: main bonding jumper [Re: ausador]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,056
Estero,Fl,usa
The issue is a parallel neutral situation or more correctly objectionable current on the grounding conductor. If you have multiple grounding points the EGC is paralleling the neutral. Since most PoCos will bond the metyer base the answer they used for years here was you nipple 3 wires into the service disconnect in PVC. Now the NEC has softened the language and says you can have line side bonding where the equipment is grouped but the MBJ is still in the service disconnect enclosure.


Greg Fretwell

#161529 - 04/03/07 10:41 PM Re: main bonding jumper [Re: gfretwell]  
Steve T  Offline
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
gfretwell, are you saying the NEC now allows the parallel neutral situation where the meter and service disco are grouped? Is that 2005?


#161559 - 04/04/07 11:17 AM Re: main bonding jumper [Re: Steve T]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,056
Estero,Fl,usa
yup 250.142(B)ex2(2) new in 2005


Greg Fretwell


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