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Joined: Aug 2004
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I have a two family home with a 200 amp service drop and two 200 amp panels this seems a little off to me because cant the two 200 amp panels draw more than the single 4/0 service drop can supply. My second question is does each panel need a #4 run for the cold water ground or can I run one and jump between the panels
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Joined: Apr 2002
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Do you have a single 200 amp disconnect at the meter or 2 200 amp disco's. If you have 1 disco with 2 200 amp panels, the single 4/0 is OK, although unusual. If you have 2 200 amp disco's then you MAY have a problem. You might want an electrician to actually look at it rather than diagnose by computer.
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Joined: Jun 2004
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I'd say the 200 amp drop seems undersized...but only if the load of the 2-family is more than the service entrance cable can handle.As for the grounding electrode conductor,I just would run one #4 to the cold water pipe and just tap the #4 above the 1st panel with a burndie and drop into the 2nd panel...don't forget to supplement with 2 ground rods!
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Joined: Jan 2003
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Check out 230.90(A)Exception No. 3 in regards to the conductor size.
Bob Badger Construction & Maintenance Electrician Massachusetts
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Joined: May 2002
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Nov, welcome to the forum. Your question is not easily answered without more information.
Read 230.90, and assuming these panels are the service disconnect, take note of Exception No. 3 specifically, which will force you back to article 220.
The water bond can be #6, see 250.104(B)
Roger
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Joined: May 2002
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Dadburnit Bob, you must of beat me by seconds Roger
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Joined: Jan 2003
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Yeah maybe, but you included 220 which will be important.
Bob Badger Construction & Maintenance Electrician Massachusetts
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Joined: Jun 2004
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Roger...if the cold water pipe is for connection of the GEC then it must be sized according to table 250.66 which would probally be a #4 copper for a 200 amp SE cable and if it were just a metal water pipe bond then it also must be sized according to table 250.66 except as permitted in 250.104(A)(2) and (A)(3) 250.104(B) is for "other metal piping"
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Joined: May 2002
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Shortcircuit, you are correct, my mistake. Roger
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Joined: Aug 2004
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There are two 200 amp main breaker panels with no disconnect outside. It is a combo meter pan. The lugs in the center definately accept the 4/0 then buss bars feed the meters. It looks like they are suppose to be 100 amp meters. Because the 4/0 SUE cable that feeds the panel from the meter did not fit under the lugs of the meter so someone made the 4/0 fit into the smaller lug by cutting off some of the strands. The lugs on the meters are one piece.
Thank you for the quick response I will read the arctice numbers that were mentioned
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