Line side trough/junction box

hhsting

Senior Member
Attached sketch shows incoming electric utility service conductors into trough/juntion box Its not a big trough but little juntion box. The service conductors go to serivce disconnect fused at 200A. There are two GEC one from service disco and second from trough/juntion box going to underground metal water pipe. There is only one service disconnect at this site.

I understand that supplemental electrode is required will be providing ground rods. However, I am not sure which section of code says to have GEC from junction box/trough to underground metal water pipe. I believe its utility trough/juntion box. Does anyone know or have encountered something like this?
 

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electrofelon

Senior Member
Not really sure why its done like that. A few possibilities:

1. Maybe the installer just didnt really know what they were doing and/or used the "more is better" philosophy.
2. Perhaps it is a bonding jumper to bond the trough? Does it connect to the neutral in the trough or the trough enclosure?
3. Maybe resulted from some dumb utility requirement.
 

hhsting

Senior Member
Not really sure why its done like that. A few possibilities:

1. Maybe the installer just didnt really know what they were doing and/or used the "more is better" philosophy.
2. Perhaps it is a bonding jumper to bond the trough? Does it connect to the neutral in the trough or the trough enclosure?
3. Maybe resulted from some dumb utility requirement.
It does connect to the neutral in the trough. The install is existing so I am not sure if it was utility requirement at the time of install.

Lets assume its not utility requirement but bonding jumper to trough and its 208/120V three phase system the way its install would it not split fault current some going from service disco neutral and some to main bonding jumper service disco to underground metal pipe to GEC to trough then to neutral reducing effectiveness of opening breaker time downstream. I am not really sure would the GEC to trough do any harm to be in place or should it be remove?
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Normally, everything on the line side of the main disco is grounded by direct connection to the neutral, as if any enclosure is a "bubble" in the neutral itself.

Also normally, any electrodes are landed in the main enclosure, especially building/water electrodes, but driven electrodes are sometimes landed upstream.
 

hhsting

Senior Member
Their is only one service discommect and trough is more like small juntion box. Would not 250.24(A)(1) allow GEC connection at trough and at main service disconnect or just one of the location is allowed to have GEC connection by 250.24(A)(1)?
 
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electrofelon

Senior Member
Their is only one service discommect and trough is more like small juntion box. Would not 250.24(A)(1) allow GEC connection at trough and at main service disconnect or just one of the location is allowed to have GEC connection by 250.24(A)(1)?
The code seems to allow only 1 grounding electrode conductor. That said, it is very common to have 2 GEC's connected at different points, such as say a GEC connected in the service disconnect going to the water pipe, and another GEC connected from the ground rods to the grounded conductor in the meter socket. No one seems to care. What you have is different as the GEC's are connected together downstream. That is no good as a creates a parallel path for neutral current, which likely would be called "objectionable" since it is easily avoidable.
 

hhsting

Senior Member
The code seems to allow only 1 grounding electrode conductor. That said, it is very common to have 2 GEC's connected at different points, such as say a GEC connected in the service disconnect going to the water pipe, and another GEC connected from the ground rods to the grounded conductor in the meter socket. No one seems to care. What you have is different as the GEC's are connected together downstream. That is no good as a creates a parallel path for neutral current, which likely would be called "objectionable" since it is easily avoidable.
If you see sketch in post #1 second GEC is connected trough/juntion box on line side of one service disconnect.
 
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hhsting

Senior Member
Normally, everything on the line side of the main disco is grounded by direct connection to the neutral, as if any enclosure is a "bubble" in the neutral itself.

Also normally, any electrodes are landed in the main enclosure, especially building/water electrodes, but driven electrodes are sometimes landed upstream.
Exhibit 250.27 does not show grounding of line side. Does anyone have picture of how line side trough and line side conduit grounded normally?
 
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