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Joined: Aug 2004
Posts: 69
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nov Offline OP
Member
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

Joined: Apr 2002
Posts: 914
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Member
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.

Joined: Jun 2004
Posts: 613
S
Member
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!

Joined: Jan 2003
Posts: 4,391
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Moderator
Check out 230.90(A)Exception No. 3 in regards to the conductor size.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Joined: May 2002
Posts: 1,716
R
Member
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

Joined: May 2002
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Dadburnit Bob, you must of beat me by seconds [Linked Image] [Linked Image]

Roger

Joined: Jan 2003
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Yeah maybe, but you included 220 which will be important. [Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Joined: Jun 2004
Posts: 613
S
Member
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"

Joined: May 2002
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Shortcircuit, you are correct, my mistake. [Linked Image]

Roger

Joined: Aug 2004
Posts: 69
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nov Offline OP
Member
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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