One Property, Two Houses...100A or 200A service?

Sugaluv40March 6, 2012

We have a property with two single family houses on one lot, in the Bay Area, CA. Both houses are 3br/2ba, each about 1400sf.

We have finished renovations on the back house. I am now trying to determine if there is a need to upgrade the existing 100A electrical service (to each house).

As stated above each house currently has 100A service. There are two meters (PGE), the panel for the front house, and a main 100A disconnect for the back house mounted at the front of the property. 150' to the rear of the property is the back house panel, being fed by #2/0 copper wire, trenched in conduit.

Both houses have gas heat, gas water heaters, and gas ranges. Both houses have electric washer, dryer, and oven. There is no AC (and never will be).

Can anyone give their input? I understand this is an uncommon scenario, and my explanation leaves many questions unanswered. But please let me know what you think and where you need more info, and I will do my best to provide it.

Thank you in advance for any help you may provide. For what it is worth, I (obviously) am not doing this work myself. I am working with a licensed electrician, but just trying to source the opinions of the forum to make sure we make the right decisions. Budget is an issue, as this work is not inexpensive, especially in our area.

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I see no reason to upgrade to 200 amp.

    Bookmark   March 6, 2012 at 6:58AM
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Sounds good to me too.
But . . . if you ever decide to split
the property up, you are going to have problems.

    Bookmark   March 6, 2012 at 9:07AM
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Reading again, is there just one meter? Get each house with it's own service, each with it's own meter. 100 amps service for each house will be sufficient.

    Bookmark   March 6, 2012 at 9:16AM
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Thank you for the replies.

Ibpod -- Yes, you are correct about splitting the property and potential problems with the current setup. However in this case it does not matter, as per the city the lot is too small to split. So I'm not worried about that in this case.

Bus_driver -- There are two separate meters. The power runs from the pole, to the mast at the front house, and then down through two separate meters. From there it branches directly to a) the 100A panel for the front house, and b) the 100A main disconnect for the back house. This main disconnect then runs the 150 feet underground (#2/0 copper) to the 100A panel on the back house.

I hope this helps answer questions, Please let me know if there is anything else.

In your estimation, if I were to upgrade to 200A, would I need to upsize the #2/0 copper wire feeding the back house? 150' of #3/0 is EXPENSIVE these days.

    Bookmark   March 6, 2012 at 11:15AM
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Local laws vary widely. The separate meters help if the occupants of each of the houses are expected to pay for their own use of electricity.

    Bookmark   March 6, 2012 at 11:53AM
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Are there two separate meter boxes, with 2 entrance
cables going up the house, or is it a
2-gang meter box with one entrance cable?
Also, if both meters are being
billed to the same person, then you would be
better off with one meter for both.

    Bookmark   March 7, 2012 at 2:17PM
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An actual load calculation will determine how large a service is needed.

    Bookmark   March 7, 2012 at 3:15PM
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