Service Entrance: 3 wire or 4 wire?

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nichols21vt

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When installing a Meter with a disconnecting means (circuit breaker), my understanding is that you always install a 4 wire feeder to the house. I understand the breaker to be my service disconnect and the conductors to the house are FEEDERS.

An experienced electrical contractor has told me that you don't have to run the 4 wire feeder but that a 3 wire service entrance cable is allowed provided you do the necessary bonding and grounding at the house.

I can't seem to find the relevant Code requirement that would allow the use of a 3 wire entrance to the house after leaving the breaker in the meter base.

Please share your knowledge!!
 
We need one more detail, and that is: is the meter on the house or on a separate structure? If on the house, anything past the main disconnect is a feeder and must have a separate grounding conductor. If the meter is on a pole with a feeder to the house, you can do 3 or 4 wire per 250.32 (depends on if there are any other grounded metal paths between structures).
 
I'm assuming you're running a lateral to the house. You can use 3-wire for that. The house is a separate structure. All the grounding and bonding will be done at the house. You'll need a ground rod at the pedastal too, and bond the neutral there. Hope that helps.
 
nichols21vt said:
The meter will be on a pedestal about 10' from the pole and 100' from the house.
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A couple of things here:

1) You can use either a 3-wire or 4-wire feeder to the house.
A) IF you use a 3-wire feeder, then you must ensure there is no other parallel grounded return path, such as a CATV cable or water pipe, etc.

b) In either case, you still have to have a main breaker or other suitable disconnecting means at the house, since your meter/disconnect is too far away to comply with the "within sight" rules (50 feet or less).

2) IF you are dealing with a mobile home, then all other bets are off, you have to use a 4-wire feeder, AND install a separate outside disconnecting means within 30 feet of the house.
 
kbsparky said:
b) In either case, you still have to have a main breaker or other suitable disconnecting means at the house, since your meter/disconnect is too far away to comply with the "within sight" rules (50 feet or less).
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There is no "within sight" rule for panelboards and transformers.

Each structure needs to have a disconnecting means.
 
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