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Bob AZ Bob  AZ is offline
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Default Running a sub panel off of a sub panel

On Oct 12, 2:10�pm, stryped wrote:
On Oct 12, 1:50�pm, Bob �AZ wrote:





On Oct 12, 8:14 am, stryped wrote:


I have a sub panel in my attached garage. It has a small heat pump/air
conditioner on it for a bonus room (I believe 50 amp) and a 50 amp
welder plug that rarely gets used.


I built a detached garage /shop with a 100 amp panel. Can I run my sub
panel in my detached garage to the sub panel in my attached garage?


I have the capability to attach it to the main panel but it would be
alot of work and would have to move 2 circuits.


Stryped


It is possible to attach this to a sub panel but you still need to
keep the neutral isolated from ground. AND you will have to limit the
100 amp panel to a 50 amp breaker from the 50 amp subpanel. And maybe
not even 50 amp since your AHJ may have further limitations on the
current loading of your 100 amp panel.


Bob �AZ


Why would I have to limit it to 50 amps?- Hide quoted text -

- Show quoted text -


Stryped

It is a code issue. And since your initial message said the first sub
panel was 50 amp I quoted 50 amp to the second panel. But with your
new sub panel information the limit is 60 amp. Again a code issue.
More than likely the 60 amp limit is part of the code limits for
branch breakers for the 100 amp sub panel. And your service panel
which I presume is 100 amp or more will have this 60 amp limit also.
At any rate you can install almost any amperage sub panel but the
breaker feeding the subpanel is limited to 60 amps. An additional code
requirement is that the continuous load limit imposed by any panel/
load is only 80% of the breaker feeding the branch circuit. The
circuit feeding the subpanel from another panel is a branch circuit
from the feeding panel. The continuous load limit is usually stated as
3 or 4 hours above or at the 80% point. And more still your subpanel
can be above the 60 amp limit to provide additional spaces for
additional circuit breakers and the associated branch circuits.

Lots to digest but if you are not sure ask your AHJ folks for
additional guidance.

Bob AZ