grounding 2 panels

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markh

New member
Location
Kansas
i have 2 200 amp disconnects, one meter.
the electrician has a grounding conductor from each 200 amp disconnect to the water line
they are two separate 200 amp discon.
where can i find the answer
they are not in parallel
sorry i was not clear.
the question is can you run a grounding electrode from eah 200 amp to the waterline?
OR, do you have to run one sized for 400 amp service to the waterline and tap that 1\0 awg
to the other 200 amp disconnect.
Can you help me with a code section and a explanation.
thanks Mark h

[ April 03, 2003, 09:16 AM: Message edited by: markh ]
 

hornetd

Senior Member
Location
Maryland
Occupation
Journeyman Electrician, Retired
Re: grounding 2 panels

Originally posted by tom baker:
What is the question? The size of the grounding electrode conductor is per 250.66
Yes, that is were the answer is found but the answer is that the Grounding Electrode Conductor must be sized by the service entrance conductors. You may not size it by the size of one disconnect even if you run two. So it should be 1/0. Running two one ought GECs would do no harm but the code does not permit two four AWG conductors for your four hundred Ampere service.
--
Tom
 

jbell59

Member
Location
Virginia
Re: grounding 2 panels

hornetd sounds like he has 2-200 amp parallel service entrance conductors, so in that case you could run 2- #4 for a GEC to each disconnecting means.
 

jbell59

Member
Location
Virginia
Re: grounding 2 panels

Correction to my previous reply, 2-200 amp parallel SE: run 2 - #4s, 1 to each disconnecting means because it would satisfy 250.66
 

hornetd

Senior Member
Location
Maryland
Occupation
Journeyman Electrician, Retired
Re: grounding 2 panels

jbell59
I disagree. Note number one to table 250.66 clearly requires that the equivalent area of the multiple sets of service conductors will be used to determine the size of the Grounding Electrode Conductor (GEC). More importantly the conductors from the meter to the individual panels are service conductor taps. The size of the GEC is based on the size of the service entry or lateral conductors between the meter and the demarcation point. In most states the demarcation point of aerial services is the splices between the service drop and the service entry conductors. It is the customer owned conductors on the line side of the meter that are the true service conductors for this purpose.
--
Tom

1. Where multiple sets of service-entrance conductors are used as permitted in 230.40, Exception No. 2, the equivalent size of the largest service-entrance conductor shall be determined by the largest sum of the areas of the corresponding conductors of each set.
 

jbell59

Member
Location
Virginia
Re: grounding 2 panels

hornedt I agree with you on note 1 of 250.66. Run a #2(2 sets 2/0 copper SE) or 1/0(2 sets of 4/0 Al. SE) GEC from the water pipe to a disconnect, however you could use 250.64(D) and run a #4 tap from the GEC to the other disconnect enclosure.

I've have never been tagged running 2 - #4s from the copper water pipes.

The parallel set of conductors from the meter to each 200 amp disconnect are considered service entrance conductors and are used for the purpose of determining the size of the GEC in 250.66.
 
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