Anthony Diodati wrote:
"CJT" wrote in message
...
I don't think it is quite that simple. Suppose you have 200 amp
service, and a panel that will accommodate only eight breakers, each
of which is occupied by a 15 amp breaker. Then the only way to access
the other 80 amps of capacity you already "have" is via a subpanel. It
doesn't really increase the capacity you have available, but it allows
you to access it. Adjust the numbers if you like, and argue about how
mis-designed my hypothetical situation might be, but the principle is
there.
That's a good point CJT, but is there really a lot or any 200 Amp mains,
that will only
hold eight breakers?
Still your point is valid.
Tony



First off adding up the ratings of the installed branch circuit Over
Current Protective Devices is not how you calculate how much of an
existing services ampacity is in use.

Second there are a hell of a lot of main lug only panels that have only
eight slots in them but the smallest breaker would have to be thirty
ampere for the panel to pass electrical inspection as service equipment.

It's important to realize that "sub panel is not a term that you will
find in the US NEC. A panel can be supplied by service entry
conductors, a feeder, the secondary conductors of a transformer, or a
local power source. Since the term itself is undefined it is difficult
to give you a good answer. I have converted multiple panel
installations to a larger service size by using a new main lug only
panel installed as service equipment to control the feeders that supply
each lighting and appliance or power panel but I doubt that is what you
had in mind.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison