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-boun...@lists.re-wrenches.org] *On Behalf Of *Greg *Sent:* Wednesday, August 21, 2019 3:12 PM *To:* re-wrenches@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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