600 ampere feeder

Status
Not open for further replies.

blues

Member
Location
Nevada
I have a utility feeder with (1)350kmcil aluminium conductor per phase. We wish to make a tap from this feeder to a 600 ampere distribution panel via a junction box. I would like to know when the NEC come in to play relative to these tap conductors. I would like to use parallel 350 copper for a tap to the 600 ampere panel.

I understand the utility has there own requiements and through historical data my feel it unnecessary to provde paralell 350 to feed this area of service.

Thank You
 
Re: 600 ampere feeder

An aluminum 350 MCM is only good for 250 amps, and you are planning to tap off this conductor to supply a 600 amp panel? :confused: I must be missing something. What is the existing load? What is the calculated load being added (i.e., on the 600 amp panel)? Have you talked with the utility yet?
 
Re: 600 ampere feeder

I don't have the answers to your questions.

In essence I believe the utility is providing what they feel is necessary for this service but as an engineer I must adhere to the NEC requirements at the point of attachment to the 600 ampere panel.
 
Re: 600 ampere feeder

Then start with a service calculation for the new panel. You need to size the feeder conductors (or are they service conductors? I'm not quite sure I understand the configuration) to be able to carry the calculated load. If you don't know that the calculated load is only, for example, 500 amps, then you have to size the conductors for the 600 amp limit of the panel. A pair of 350 copper would do that job.

You will have to coordinate with the utility. If you give them the new total load, it will be up to them to change the service conductors, if they see the need.
 
Re: 600 ampere feeder

You are mixing service laterals (not NEC, utility) and feeders (NEC). Utilities typically size the service lateral to the transformer and to a derated factor of the service main. For example, the utility kows that a service with a 2000A main breaker will seldon run over 1000A so they size their transformer and service lateral for 1000A. If you want to pull a feeder, you need to do it on the customer (load, NEC) side of the main beraker or add a main (up to 6) and take the feed that way. You need OC protection at the feeder source. If you are adding another service point, work with the utility because their rules will apply, not the NEC.
 
Re: 600 ampere feeder

the first thing you need to do is find out where the service point is! Definition article 100. This can and will change with each utility. Remember the NEC rules only apply after the service point. That could be at the transformer, the main, the weatherhead, etc. Once the service point is established, follow the minimum standards set in the NEC and that is all you can do. The utility has their own rules and regulations set by themselves, you cannot change them.
 
Status
Not open for further replies.
Top