The utility feed to my duplex with two 100A meters on it, is an underground cable in conduit. The main panel is 200A, but the utility feed is only 2 AWG Aluminum. The cable marking is: ALCAN 2 AWG ALUM 600 VOLT XLPE 1978. I think XLPE is Cross Linked Polyethylene, which I think has a higher temperature rating.

This document shows that a single conductor is good for 180A for direct burial. Is it appropriate to use that value in a conduit?

When I looked at the 90C rating for #2 Aluminum, I see 100A. Can someone explain why the other document shows it as 180A?

I'm assuming 180A is fine for two 100A breakers in a duplex, assuming some level of diversity. The cable going into the panel is a 2/0 Copper, but it is only 4 ft or so from the box you see into the panel

detail showing 2 AWG XLPE cable Overview showing panel and junction box Junction box with utility connection Panel busbar detail

1 Answer 1


Being in conduit vs direct burial makes no significant difference on ampacity.

Since it is on the utility side of the meter, and the wire was provided by the power company, this is a big bag of Not Your Problem.

The power company has two smart meters that record your peak energy usage. They will know when your usage is of concern, and will send out a truck with marshmallows and graham crackers.

Now what is the deal with the three loose conductors stapled to the side of your house? Please, tell me they are 2 AWG XLPE telephone lines, and the one with the white stripe is cable TV...

  • 2
    Thanks so much, I agree that it is the power company's problem, but since I'm about to have an electrician replace that Zinsco meter main, I didn't want the utility to come back and say 'oh you need to upgrade your feed', because somehow I have a feeling they would make me pay. Those loose stapled conductors are cable TV and I think from an old satellite dish. Thanks for asking. There is a somewhat hokey #6 bare ground wire exiting the box that was put in by the solar installer. I've actually queried the smart meter and found out that my max draw was 13 kW, so about 55A. Aug 2, 2019 at 3:40

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