Grounding electrode 250.64(D)

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Leespark57

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Boston, MA, USA
After reading the other thread about the 320 meter socket here is my question:

Let's say you have a service with a multi gang meter socket (no disconnects, not more than 6). Immediately inside the building are main breaker panels serving as the service main disconnects fed with SEU cable. Typically I would install my GEC to 1 of the panels and then use split bolts to feed the remaining panels with taps. Would it be acceptable to instead install a single GEC to the multi gang meter socket and nothing to the MB panels? (again, no disconnects at the meters) The only restriction I can see is if the power company objects to this, but it is common practice around here to run the supplemental ground into the meter enclosures. It would be easier and cleaner, but would like others opinions.
 
Yes it would be compliant to just feed the meter main for the six panels. The wire would have to be sized for the service conductor size - which would be larger than going individually from each panel.
 
Dennis Alwon said:
Yes it would be compliant to just feed the meter main for the six panels. The wire would have to be sized for the service conductor size - which would be larger than going individually from each panel.
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Actually he indicated this was not a meter/main setup.
Meters only, not that I see where it would make a difference.

JAP>
 
Leespark57 said:
The only restriction I can see is if the power company objects to this, but it is common practice around here to run the supplemental ground into the meter enclosures.
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There is an argument that the real benefit of a supplemental ground is that it can best handle energy surges (transients) with very fast rise times, and that the more direct the path to earth the better. The fewer bends, and the shorter the distance, to the supplemental ground, the better. Something like a lightning induced surge is handled better.

But the Grounding Electrode Conductor might be another story, in the minds of your local power company, as it is more likely (although there are exceptions to this generalization) to be a significant part of the occupancy overcurrent protective device's effective fault clearing current path. Whether your local power company will allow access, for servicing, to the inside of their "cash register" meter socket for the GEC may well be thought of differently than a high voltage transient capable supplemental ground.

None of my opinion, above, is handled directly in the Code.
 
I tend to think that the GEC connection in the meterbase is the best place for it to be.
Less likely anybody will jack with it in there.

JAP>
 
jap said:
I tend to think that the GEC connection in the meterbase is the best place for it to be.
Less likely anybody will jack with it in there.

JAP>
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Also completely unserviceable and unmaintainable as most poco's seal or lock the meter enclosure. My 2 cent.
 
Can you do this we usually use one of these if there is more then one panel
cfe5c84502767f13637a0d487f8e08a8.jpg


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If either of the two green runs is a GEC rather than a bonding jumper, you have failed to deliver an irreversable splice between electrode and either panel.


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The two greens going.to each panel are bonding jumpers from the neutral bar

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nickelec said:
Can you do this?

we usually use one of these if there is more then one panel
cfe5c84502767f13637a0d487f8e08a8.jpg
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It looks like you have a bare stranded #4 heading off in the EMT. It looks like the #4 is the grounding electrode conductor.

It also looks like you have a green #6 going down out of photo which I assume is going to a supplemental grounding electrode.

The problem with this assembly is coming from the rule 2017 NEC 250.64(C). Lugs are not allowed to splice the grounding electrode conductor.

It looks like you have two green #6 coming out of what I assume are two 100 A service disconnects. If those two green #6 were irreversibly spliced by means in the rule 250.64(C) to somewhere on the length of the #4 then that would work for the #4 to land on the lug attached to copper bar, and the grounding electrode conductor would be continuous into the service disconnects.
 
Or, to look at it another way, you cannot have your ground to neutral bond on a bus bar outside the several panels and call the wire(s) back to the panels bonding jumpers. The bond can occur at a meter, or at a service disconnect. Not out in free space.
 
GoldDigger said:
Or, to look at it another way, you cannot have your ground to neutral bond on a bus bar outside the several panels and call the wire(s) back to the panels bonding jumpers. The bond can occur at a meter, or at a service disconnect. Not out in free space.
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:thumbsup:

And if those 2 green conductors are actually coming from the insulated neutral bars in those 2 load centers, or directly from the ground bar only, and those 2 loadcenters have main breakers and are actually serving as the service disconnects, and that's where they meant to bond, then there is actually no bond at all inside those 2 panels if the actual bonding screw that is supposed to be used for the bonding jumper was not installed.

whewwwww......

JAP>
 
If a fault current returned on the branch circuit EGC's to the ground bar bolted to the panel tub, there would be no way for the fault to clear if the bonding jumper is not actually installed between the ground bar and the insulated neutral bar, which would in turn, energize all normally non current carrying parts of the system, leaving a potential for an electrical arc or for some unsuspecting person to come along and create a path to get their butts knocked off.

JAP>
 
I don't see an issue with this

A grounding electrode conductor tap shall extend to the
inside of each disconnecting means enclosure. The grounding
electrode conductor taps shall be sized in accordance
with 250.66 for the largest service-entrance or feeder conductor
serving the individual enclosure. The tap conductors
shall be connected to the common grounding electrode conductor
by one of the following methods in such a manner
that the common grounding electrode conductor remains
without a splice or joint:
(1) Exothermic welding.
(2) Connectors listed as grounding and bonding equipment.
(3) Connections to an aluminum or copper busbar not less
than 6 mm thick × 50 mm wide (1⁄4 in. thick × 2 in. wide)
and of sufficient length to accommodate the number of
terminations necessary for the installation. The busbar
shall be securely fastened and shall be installed in an
accessible location. Connections shall be made by a listed
connector or by the exothermic welding process. If aluminum
busbars are used, the installation shall comply with
250.64(A).
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To me, as long as they are not considering the 2 green wires coming out of the 2 panels as the the "Main" Bonding Jumpers for those 2 panels, the picture pretty well is to a Tee what that paragraph just explained.

If the bare conductor in the picture is the "Main common grounding conductor" and it is not spliced anywhere between where it terminates at the bussbar and whatever Grounding Electrode it's attached to at the other end, I can't see a problem with it at all.

It just says, that portion between the bussbar and the electrode on the other end must not have a splice in it in my opinion.

JAP>
 
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