QO Breakers and Panels [RE-wrenches]

[Bob-O Schultze, Electron Connection]

<x-flowed>>Are Square D QO 's rated for 48 volt (battery) systems?  I know that Wiles
>mentions Q0 in his Sandia Handbook but I can't find it.   From memory it
>seemed like the wording was possibly a little ambiguous about 48 systems but
>like Smitty I suffer from C.R.S.

No. They are rated for 48VDC which is below the normal operating 
voltage in a 48V system. Wiles even has a problem with them in 24V PV 
systems because the PV open circuit voltage X 1.56 exceeds 48V. THAT, 
in my opinion, is just ridiculous. During normal operation they never 
see more than 32VDC or so.

>
>Also who determined that QO are O.K. for use in DC?  There is no mention of
>them being DC rated on the breaker or the panels themselves.  For example..
> We frequently use 250 V AC/DC disconnects (not 240 v) available at any
>electrical supply house and they do say "250 volts DC"  on them.

They are listed in the Square D Digest as OK for 48VDC. If you buy 
enough of them from your supplier as I do, ask them to get the 5272 
versions. A part # for a 20A breaker, for example, would be 
QO1205272. The 5272 version has a cute little sticker on the side of 
it which states that it is rated for 48VDC. Should be enough to get 
the nod from any inspector who cares to ask. The difference between 
the 5272 and any "regular" QO breaker? As far as I can tell, it's the 
sticker!

>
>Has anyone had trouble with inspectors catching this?  I never get inspected
>on my rural jobs.  I'd pull a permit if there was someone to get it from but
>in rural MO and AR there isn't.  I do get inspected several cities but I
>haven't done any DC load centers on these jobs.
>
>In the last few years Square D came out with a "Homeline" brand of 1"
>breakers and panels.  Has anyone heard if they are rated for DC?
>

The Homeline is not, just the QO and QOU series.
Bob-O

Bob-O Schultze, Electron Connection
PO Box 203, Hornbrook, CA 96044
800.945.7587 or 530.475.3402
fax 530-475-3401
www.electronconnection.com

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