4/0 copper is good for a 24V, 4000 W inverter. What is being used for multiple inverters?
I've paralleled 4/0 into outback boxes using 2, 2" PVC conduits. It gets pretty messy trying to put 4 sets of 4/0s into enclosures and battery boxes (although I have worked on such systems). Does anyone have clean solutions for these systems? Thanks, Drake > Some other things: If you keep the conduit less than 24" long, which is > recommended anyway for main battery connections, the conduit fill > requirements don't apply. (see exception: 310.15(B)3a2) > Using table 310.15(B)16 yeilds 230 amps for 4/0 at 75 C. Then 240.6 > lists 250 amp as the next standard size of OCPD which is allowed to be > used by 240.4(B) So you can just justify 4/0. > Further, many manufacturers (like Midnite) use the open air ampacity > table: 310.15(B)17, since the cable is not "in conduit" and 4/0 cable at > 75 C is rated to 360 amps. > The Free Air interpretation is not completely substantiated in the code > from my read of it though. Maybe someone more knowledgable could cite > the chapter and verse that defines when the free air rating can and > cannot be used. > Also remember those breakers are 100% duty cycle rated, and that the > inverter usually can't run any where close to 250 amps continuously. > Bottomline is we've been using 4/0 with 250 amp breakers for almost 20 > years, and I've never seen or heard of a problem. > > R.Ray Walters > CTO, Solarray, Inc > Nabcep Certified PV Installer, > Licensed Master Electrician > Solar Design Engineer > 303 505-8760 > > On 1/1/2015 7:23 PM, jay peltz wrote: >> Happy new year all. >> >> I have a question on wire sizing for the following. >> >> 250 amp breaker, in a UL enclosure ( say midnite or outback etc) >> conduit from battery box to enclosure >> >> I'm wondering how folks size this for ampacity not voltage drop. >> >> thanks >> >> jay >> >> peltz power >> >> >> >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: [email protected] >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://www.mail-archive.com/[email protected]/maillist.html >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> www.members.re-wrenches.org >> >> > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/[email protected]/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > _______________________________________________ List sponsored by Redwood Alliance List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/[email protected]/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
