200 amp service-2/0 cu thw

av8rFebruary 5, 2013

We are replacing an old main box on the house that does not have a main breaker. The box is opposite the meter pan. Meter pan is on outside and there is a short nipple and then the main box is on the inside of the same wall. Old box had no main breaker. New box has 200 amp breaker. Underground service to meter pan is 4/0 aluminum. Wire between meter pan and main box is 2/0 cu thw. Do I need to upgrade this to 2/0 thhn cu or is it ok to leave this old wire? Thanks in advance.

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Follow up question to the above. Noticed that the wire feeding the main sub panel in the house about 80 feet away is a 4/3 cu nmb. It is on a 100 amp breaker. Should this be downsized to a 70 amp breaker? Thanks again.

    Bookmark   February 5, 2013 at 1:08PM
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The 2/0 cu is fine as far as that goes. Your inspector may insist on new if the insulation on the existing shows any sign of aging- or for personal preference.
Yes, the #4 should be on a 70 amp breaker. Will that handle the expected load?

    Bookmark   February 7, 2013 at 11:27AM
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It feeds the main panel in the house for all of the branch circuits. 40 circuits all single pole. 2500 s.f. House. I would think that it would. The biggest items look to be heaters in the 3 bathrooms and also the various kitchen circuits. Thanks again for the advice.

    Bookmark   February 7, 2013 at 12:42PM
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