Electrode question

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Curryb

Member
Location
Carson city
Occupation
Electrician
Hello I am installing a 400 amp meter main at the bottom of a driveway on a pedestal and feeding two 200 amp transfer switches up the hill at the house . I will have an electrode at the meter main but it is my understanding that I need an electrode at the house as well. I can not use the EGC in the feeder to serve that purpose. Some guys are saying I am wrong. After looking in article 250 section 3 seems I am correct but am wondering everyone’s opinion. In article 250.118 B 1 there is an exception saying you can use both for same purpose but I think I am confused. Thanks again for your input
 
Curryb said:
Can you elaborate? And thanks for the reply
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225.30 Number of Supplies.
A building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit.

250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s).
(A) Grounding Electrode.
Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250. The grounding electrode conductor(s) shall be connected in accordance with 250.32(B) or (C). Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.
 
In '17, the 2 feeders would not be allowed (225.30)
In direct answer to your question, a GES would be required at the residence.

(opps answered on top of don)
 
The later codes permit the multiple sets of conductors to a single building (how a 400A resi service is typically done). See 225.30(B) in the 22023 NEC. So you may want to check with your AHJ if they will allow it. Eventually they will once they adopt a later code, but may be amenable to letting you do it now.

No way out of the ground electrodes though. The only gray area is if the service pedestal is detached from the building but close, like 2' away or 5'. At some distance (end of the driveway for sure), the two structures are are separate enough that each needs their own ground electrode. And a strict reading of the code gives no allowance even for adjacent structures that are not attached.
 
What do you do if the home has a 400 amp service meter at the street house on the hill and you can only run one feeder ??? I can get a 400 amp transfer switch but one feeder for 400 amps seems like parallel feeds is a must I’m new to the trade in my opinion just finished school and passed j test so I know I dam sure have a lot to learn still. Thanks for all the feedback back guys. And help
 
Curryb said:
What do you do if the home has a 400 amp service meter at the street house on the hill and you can only run one feeder ??? I can get a 400 amp transfer switch but one feeder for 400 amps seems like parallel feeds is a must I’m new to the trade in my opinion just finished school and passed j test so I know I dam sure have a lot to learn still. Thanks for all the feedback back guys. And help
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Can you run a single 400 amp feeder to the house and then split it there?
 
One tip: Unless there is a utility or local rule, I would avoid the service disconnect at the meter. Have a meter only and send service conductors up the hill. A like to avoid unneccesary pieces of equipment and then you can run 3 wire instead of 4. Are these service rated transfer switches? In that case you would probably run two 200A sets, one to each transfer switch. The code that covers that is 230.40 exception #2
 
Curryb said:
but one feeder for 400 amps seems like parallel feeds is a must
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Why is a parallel feed a must?

Note, that does not mean you can't parallel two sets of 3/0 to create a single 400 amp feeder. At the building you could set a junction box and tap off the parallel feeder to two 200 amp disconnects following the tap rules in 240.21(B).
 
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