400 amp service

[wayne123]

I am installing a 400amp service on a house that consist of 1-400 amp meter, 1-400 amp transfer switch and 2-200 amp main breaker panels(all outside.What is the proper way to ground this.There are no metal water pipes in the house so I am going to install two driven ground rods.Do I run the GEC to the meter to bond the neutral to it then loop through the TS and the two panels.Any advice will be appreciated.

 

[tom baker]

Re: 400 amp service

Is your transfer switch service entrance rated? Is it a fused or have a main circuit breaker?

 

[wayne123]

Re: 400 amp service

It is not fused nor does it have a CB.Its just a manual TS with blade contacts

 

[wayne123]

Re: 400 amp service

It is service entrance rated.

 

[tom baker]

Re: 400 amp service

I've seen a couple of these done with a non-OCPD transfer switch ahead of the service. The grounding electrode conductor termination was done differently in each one. I would go over this with your AHJ before installation.

 

[hornetd]

Re: 400 amp service

You can make the connection of the Grounding Electrode Conductor to the grounded service conductor at any convenient point between the end of the service drop or lateral and the service disconnecting means enclosure's bonded buss bar. The transfer switch is probably the easiest place to do that. Some electrical utilities require you to make the connection at a specific point so check with your AHJ before committing to a particular approach. As an example the rural power cooperatives that were set up by the Rural Electrification Administration (REA) used to require that the connection be made to the neutral drip loop. The people who wrote the original REA service standards believed that this practice offered superior lightning protection to services supplied form overhead lines. Some of the utilities still adhere to that practice.

250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).
(1) General. The connection shall be made at any accessible point from the load end of the service drop or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.
--
Tom

 

[wayne123]

Re: 400 amp service

Thanks hornetd, I think I will terminate theGEC in the meter where the grounded cond. comes in from the utility. I am also installing a gutter under all four panels. Whats the best way to ground it ?

 

[hornetd]

Re: 400 amp service

Originally posted by wayne123:
Thanks hornetd, I think I will terminate the GEC in the meter where the grounded cond. comes in from the utility. I am also installing a gutter under all four panels. What's the best way to ground it ?

Some utilities will not permit the termination of the Grounding Electrode Conductor (GEC) in the meter enclosure so ask the utility engineer first. The neutral block of the transfer switch is a good place to terminate the GEC.

In order to answer your question about grounding the gutter we would need to know whether it will contain service entry conductors or feeder and branch circuit conductors.

Best practice is to completely separate the service entry conductors from the generator conductors except in the transfer switch itself. I would route the meter load conductors into the bottom of the transfer switch, the generator conductors into the top of the transfer switch, and the transfer switch load conductors to the panels as remotely as possible from the service entry conductors. The actual layout will depend on whether the service is overhead or underground.
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Tom