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Bruce L. Bergman[_2_]

On Mon, 13 Jul 2009 23:24:03 GMT, (Doug Miller)
wrote:

In article , wrote:
On Mon, 13 Jul 2009 11:33:43 -0700 (PDT), stryped
wrote:

What do you mean if I installed it the same as the main panel it is
wrong? I put a (rated) 100 am sub panel right next to the main panel.
There is a 100 amp breaker in the main panel feeding the sub panel and
also a 100 amp main breaker in the sub panel. the ground in the sub
runs to the grounding bus in the main panel.

One of the 100 amp breakers is redundant. Won't hurt anything but not
required if the panels are side by side.

Specifically the 100A breaker in the subpanel is redundant. The 100A breaker
in the main panel is required, to provide overcurrent protection for the
feeder to the subpanel.

In his new building, he needs both: one whichever panel the feeder is taken
from (to protect the feeder), and one in the subpanel in the new building (to
provide a disconnect for that building).

Having another Main Breaker disconnect in the subpanel in the
detached building isn't an absolute necessity if you have six or less
circuits in the sub-panel (Per 2002 NEC Article 225.32 and the
exceptions see "Installations under single management", and Article
225.33)

But it is still a darned good idea to have another Main - so you can
Kill It all RIGHT NOW. Cheap insurance, but it does make another
point to find and reset if you get a nuisance trip...

You have to keep the Neutral and Safety Ground totally seperate
except at the Main Service Panel - meaning you need to run four wires
out to the detached shop. Two hots, Neutral and Ground.

Meaning if it's an aerial run you have to buy Quadplex aerial
service wire to get three insulated plus a bare messenger for the
ground. Triplex like Edison uses won't cut it.

-- Bruce --