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#99636 - 08/22/06 08:47 AM Classroom confusion
Alan Nadon Offline
Member
Registered: 03/10/05
Posts: 399
Loc: Elkhart, IN. USA
This is the situation.
Portable classroom composed of two halves, (think of a double wide mobile home) each with a 100 amp main breaker panel that controls the circuits in that half of the building.
The electrician brings TWO 100 amp feeders out to the panels. Each originates in the same service panel with a 2pole 100 breaker.
Based on 225.30 (formerly 225.8 & 9[1996] and 230.84[1990]) only ONE feeder or branch circuit, with exceptions for firepumps etc.
To comply with the Code should the electrician (1) use a 200 amp breaker listed for two conductors per pole (2) handle tie the two 100 amp breakers, (3) either or (4)something else ?
Note the panels inside are ten feet apart.
We build them around here and use them but, I'm just not sure.
Alan--
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#99637 - 08/22/06 09:56 AM Re: Classroom confusion
earlydean Offline
Member
Registered: 12/22/03
Posts: 751
Loc: Griswold, CT, USA
I would supply a small 150-200 amp main breaker panel mounted on the outside of the classroom, then feed each panel with a 100 amp feeder. Maybe even supply a branch circuit for outside lighting.

It may be, that when the calculations are done for the combined load of both halves, that a 100 amp feeder would suffice. If so, then you could feed the closer panel, and subfeed the other from the first.
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#99638 - 08/22/06 12:44 PM Re: Classroom confusion
Tom Offline
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Registered: 01/01/01
Posts: 1044
Loc: Shinnston, WV USA
I'm thinking a single 200 amp feeder run to a 200 amp disconnect mounted inside or outside the structure. If you feel that the two inside panels are "grouped" as required by 225.34(A), then the feeder can be run to the structure and then tapped at that point.
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#99639 - 08/24/06 11:09 AM Re: Classroom confusion
Alan Nadon Offline
Member
Registered: 03/10/05
Posts: 399
Loc: Elkhart, IN. USA
Problem solved
One disconnect, (service or not) rated 200 amps (225.30 & 34) with one feeder to each double classroom.
At the classrooms a W.P. junction box with two 100 amp taps (per 240.21 tap rule) to the panels.
Done & Done.
Alan--
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Alan--
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#99640 - 08/24/06 12:13 PM Re: Classroom confusion
earlydean Offline
Member
Registered: 12/22/03
Posts: 751
Loc: Griswold, CT, USA
And don't forget to install a couple of ground rods.
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Earl
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