Two 100a panels GEC question

[mark32]

In a multi family dwelling there is a 200a service, after leaving the two meter meter pan, the feeders then feed two 100a main breaker panels. My thinking is you can run a # 4 cu from just one of the panels to the grounding electrode instead of some other arrangements that I've seen/heard. One friend jumped the two panels in the scenario above, I told him he probably didn't have to do that but he said he'd fail if he didn't. I don't agree with this as the feeders in this case contain a grounded conductor sized large enough for the whole 200a service which are of course bonded together at the meter. Does anyone see a problem with this?

 

[augie47]

If allowed by POCO you could run (1) grounding electrode conductor from any point starting at the point of attachment to the service disconnect.
In this area that is often at the meter socket.
If you use one of your service disconnects as the attachment point, you must also use the other. see NEC 250.62
Possibly a #6 from each (assuming #3 service) or a #4 to one with a #6 tap to the other.

 

[infinity]

Here's a good graphic of one method from the NECH.

 

[suemarkp]

If allowed by POCO you could run (1) grounding electrode conductor from any point starting at the point of attachment to the service disconnect.
In this area that is often at the meter socket.
If you use one of your service disconnects as the attachment point, you must also use the other. see NEC 250.62
Possibly a #6 from each (assuming #3 service) or a #4 to one with a #6 tap to the other.

See what? 250.62 doesn't seem relevant to that in my book.

 

[augie47]

stupid book snuck a heading in on me 250.64

 

[guschash]

You had me looking Augie.

 

[Pierre C Belarge]

You had me looking Augie.

Me too... I always look when Augie supplies a code section.


lets keep it sharp Augie. :grin:

 

[augie47]

View attachment 3221

sometimes I forget my glasses (and my mind)

(I fogot who to thank for the pic..see memory prioblems too :smile

 

[Pierre C Belarge]

Augie
That image almost looks like your avatar. :grin:

 

[mark32]

Thanks for the replies. In the pic Infinity kindly posted, is it not permissible to run a #2 in this case from just one of the panels to the grounding electrode?

 

[Dennis Alwon]

Thanks for the replies. In the pic Infinity kindly posted, is it not permissible to run a #2 in this case from just one of the panels to the grounding electrode?

Well, in the graphic Trevor gave we don't know whether there are meters afters the disco or just one meter for both panels. If there is one meter for both panels then I do believe that a #2 can go to one of the panels.

 

[iwire]

Well, in the graphic Trevor gave we don't know whether there are meters afters the disco or just one meter for both panels. If there is one meter for both panels then I do believe that a #2 can go to one of the panels.

The number of and position of the meter(s) is irrelevant.

The GEC must run to each enclosure containing a service disconnecting means.

 

[augie47]

The number of and position of the meter(s) is irrelevant.

The GEC must run to each enclosure containing a service disconnecting means.

Bob, It is acceptable to connect the appropriate sized GEC ahead of multiple service disconnecting means such as in the meter, or in infinity's sketch, in the wireway, correct ?

 

[iwire]

Bob, It is acceptable to connect the appropriate sized GEC ahead of multiple service disconnecting means such as in the meter, or in infinity's sketch, in the wireway, correct ?

Yes you are correct, my mistake.

 

[RUWired]

Yes you are correct, my mistake.

Thats only correct for service conductors that are common with multiple service disconnects. With GEC taps and single services, the GEC has to go to each service disconnect.250.64(D)1,2,3

Rick

 

[mark32]

Okay, I think I got it. One could do as is shown in the graphic Infinity posted, that being, dropping out of each panel with a gec and split bolt it to the full sized gec that runs to the grounding electrode. That, or bonding a full sized gec to the trough, and grounded conductor, in the trough prior to the panels, correct? I believe my initial post about running the gec from one (Main) panel would now be incorrect, yes?

 

[MF Dagger]

Now to catch the rebar in this situation would it be acceptable to drop a seperate ground out of each panel?

 

[mark32]

Hey Dagger, I believe you could just split bolt the gec from the rebar to the other main gec that the panel drops are split bolted to.

 

[augie47]

Now to catch the rebar in this situation would it be acceptable to drop a seperate ground out of each panel?

Permissible, yes

Hey Dagger, I believe you could just split bolt the gec from the rebar to the other main gec that the panel drops are split bolted to.

as long as the the other gec was at least a #4 per {250.66(B)}