Before purchasing my home, I had the builder install a sub-panel in the basement. The two hot feeder wires are #2 Al and the one neutral is #4 Al, its just a 3 wire feed. The feeder wire runs about 40 feet in pvc counduit from the main panel in the garage to the basement. The feed is protected by a 100amp breaker in the main panel. The sub-panel was only a 40 amp generator feeder with 8 slots (probably the cheapest thing the builder could buy). I have removed it and bought a 22 slot 100 amp panel.
After reading lots, and lots, and lots of posts about sub-panel installations I am concerned and confused with what the builder did, plus I know he did it after the electrical inspection. My questions are below.
1) From everything that I read, since the panel is in an attached building he should have run a 4 wire feed from the main panel to the sub-panel 2-hots, 1-ground, and 1-neutral, is this correct?
2) Even if a 3 wire feed is okay, I don't think a 100amp breaker in the main panel is up-to-code. I think it should be at max a 90amp breaker, is this correct?
3) If I do need to rewire the feed with 4 wire, what is the recommendation on size and type? Keep in mind that I bought the 100amp panel for the number of slots, not because I think I will ever need 100amps. I doubt I will ever exceed 60 amps.
4) The new 100amp panel has a green bonding screw to bond the neutral bus bar to the enclosure (the equipment ground is already bonded to the enclosure), I know if I had a 4 wire feed I don't install this because I will isolate the neutral and ground with separate wires, but if a 3 wire feed is okay, should I bond the neutral to the enclosure?
Thanks,
Eric
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