[RE-wrenches] 30 amp disconnect/40 amp breaker

[William Miller]

Greg:



Unless your disconnect is specifically rated for continuous duty, you have
to up-size it by 125%.  To my knowledge, disconnects are not generally
rated for continuous duty.  A quick review of the Square D Digest (as an
example of but one manufacturer) indicates that only one high-end type of
disconnect switch carries a continuous duty rating.  I am fairly certain
your garden variety disconnect does not carry this rating.  Therefore you
must apply the upsize calculations.



25*1.25=31.25. You cannot use a 30A disconnect.  Sorry to disagree.  There
is no benefit to cutting corners.  I remind myself daily that electrical
equipment, when misapplied, can kill.



William Miller



Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985



Quote of the month:  “As they age, batteries transition from energy

storage devices to energy consuming devices.“ W. Miller



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Greg
*Sent:* Wednesday, August 21, 2019 3:12 PM
*To:* re-wrenches at lists.re-wrenches.org
*Subject:* [RE-wrenches] 30 amp disconnect/40 amp breaker



Fellow Wrenches,  I'm having a discussion with a utility engineer regarding
the following situation:

Installing a 6kW inverter that has a full rated output of 25 amps.  80% of
30 is 24.  That means to me I need to go up to a 40 amp breaker.  I'm
running #8 (continuous load 25 x 1.25 etc.)
The engineer believes I should use a 60 amp disco since it's on a 40 amp
breaker.  My thinking is I can use a 30 amp disco since it can not produce
more than 25 amps ever.

Do any of you have a reference that shows what I'm doing is okay? Not
okay?

Thanks again,
Greg Egan
Remote Power Inc.
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