New Service Panel

mikec205October 27, 2010

I have a detached studio on my property built in the 50's, I have removed the old "screw in" style fuse box and all of the wiring and want to install a new panel. The main power comes from a huge cable that runs about 100ft back to a 100amp knife switch.

What type of panel do I need: Main Breaker, Main Lug or transfer panel? I don't understand the differences.

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Ron Natalie

A main lug only panel will be OK, though it may be cost effective in some circumstances (and perhaps convenient) to install a main breaker.

Things to check are to make sure your grounding electrode (rods typically) at the detached building is in place, that the 100A fuses in the feeder are in fact the right size for the size of wire used.

    Bookmark   October 27, 2010 at 7:58AM
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If the panel has more than 6 breakers then you need a main breaker or a separate disconnect at the detached building.

    Bookmark   October 27, 2010 at 8:19AM
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This sounds like an older installation. There are several considerations in upgrading such an installation - for example, the feed to your building may not meet current code grounding requirements.

At the very least, you'll need to be sure the feed is protected by an appropriately sized overcurrent device. A knife switch (!) isn't sufficient.

You may be getting into more than you bargained for here.

    Bookmark   October 27, 2010 at 1:21PM
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i would use a squareD qo main breaker panel

    Bookmark   October 27, 2010 at 9:20PM
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I just left a "knife switch" (enclosed type) in service as a disconnect for a residential furnace.

Charming contraption, original manufacturer (Trumbull) rated it to 30A, it's on a 15A circuit. It's in quite good condition.

I did replace all of the wiring on that circuit though. What a !@#$ working in a box that tight.

    Bookmark   October 27, 2010 at 11:43PM
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