[RE-wrenches] Square D Disconnects mounted on the slope of the roof.

Mon Nov 11 10:37:24 PST 2013

Bob O......thank you, you got to the heart of my original question....I am
not questioning the OCPD ratings....just the can mounted at a slope
equivalent to the roof slope.....Typically if we have rooftop OCPD they are
high voltage fuse holders and fuses or the Outback and Midnite solar
breakers.....I haven't actually looked up the temp ratings on those but
have assumed (i know) that they are rated for roof top temps as they are
marketed as combiner box breakers and combiners are often located on the
hot roof next to the modules....Oregon has a rule where many jurisdictions
are now requiring lockable, visible disconnects on roofs for fire fighters
to be able to disconnect the array from the BOS down below from up on the
roof.....In my opinion this is of limited use in micro inverter and
optimizer systems.....but i can see some limited value in high voltage
string inverter systems......I should also note that i am primarily
referring to smaller residential systems.....(~3-10Kw)
>From what i have gleaned from this discussion, Midnite solar has a single
circuit 600V disconnect, (apparently a multi string disconnect as well, I
haven't fully researched that all the way thru yet) DC Sunvolt out of NJ
also has a line of disconnecting combiners which we have used a few times,
and  Crouse Hinds has some jumbo disconnecting combiner boxes that are way
over sized and also over priced.....
Thanks for all your input...

Sunny Regards,
Kirpal Khalsa
NABCEP Certified PV Installation Professional
Renewable Energy Systems
www.oregonsolarworks.com
541-218-0201 m
541-592-3958 o

On Mon, Nov 11, 2013 at 10:09 AM, Bob-O Schultze <
bob-o at electronconnection.com> wrote:

> Dan,
> I think this thread applied not to OCDs but to an unfused 600VDC
> disconnect can mounted on a roof which is less than vertical.
> Bob-O
> On Nov 11, 2013, at 9:21 AM, Exeltech wrote:
>
> Wrenches,
>
> There appears to be some misinformation getting into this thread.
>
> The "trip" mechanism within standard thermal over-current protective
> devices ("OCP devices") is mechanically spring-loaded, and is triggered by
> heat.
>
> Eric mentions below that Square D breakers are tested in a vertical
> orientation only - the implication being that's their only "UL certified"
> position.  If this were true, it would imply the breakers cannot be used in
> any other orientation.  This would potentially limit the Square D OCP
> market to sub-panels and other enclosures where the devices are vertical.
>  Inasmuch as the vast majority of panelboards I've encountered in my 40+
> years in this industry have the breakers stacked horizontally, it would not
> be a wise business decision for the manufacturer to self-inflict such a
> limitation on their product.
>
> This also does not mean any such limitation (real or not) applies to all
> breakers.
>
> By way of example, OCP devices work in a horizontal position, stacked
> "pancake" style in a main panelboard, as well as vertically oriented
> side-by-side in a sub-panel.  In either orientation, they are  in full
> compliance with UL 489, (UL Standard for Circuit Breakers, Switches, and
> Circuit Breaker Enclosures).  If an OCP device *was*
> positionally-sensitive, UL Standards require this sensitivity to be noted
> in the documentation accompanying the device.  Further to that point, UL
> 489 Section 7.1.1.13 states: "In determining if a circuit breaker complies
> with the test requirements, the device shall be mounted or supported as in
> service and tested under conditions approximating those of intended
> operation, except as otherwise noted."
>
> Mounting position notwithstanding, a greater concern would be the ambient
> temperature of a rooftop location, whereby summer heat would tend to make
> the OCP device more sensitive than necessary, potentially causing it to
> trip at an amperage below that of its UL ratings.  While a nuisance, a more
> serious issue arises when operating the OCP device in cold ambient
> conditions, whereby the device may allow MORE than its rated trip current
> to flow.
>
> Per UL 489, OCP devices are tested at either 25C or 40C ambient.  Again
> per UL 489, if an OCP device is to be used in ambient conditions other than
> those two ranges, the acceptable temperature range for that OCP device
> shall be marked on the body of the device.
>
> In UL 489, Supplemental Annex, Section 2, Subsection 2.3.3, mechanical
> vibration testing is conducted with OCP devices oriented vertically,
> horizontally, and inclined 30 degrees from vertical, with all devices
> energized up to 200% of the device rated current during the testing.
>
> Given the preceding, and per implication of UL 489 testing methods, OCP
> devices are NOT positionally sensitive.
>
> In conclusion, if you DO install a rooftop OCP system, and for proper
> protection, please ensure the OCP devices utilized are rated for the
> worst-case ambient temperatures involved.
>
>
> Regards to all,
>
>
> Dan Lepinski
>
>
>
>
> At 09:33 AM 11/8/2013, you wrote:
>
> Hi Kirpal,
>
> All Square D safety switches are UL tested in the Vertical position ONLY,
> so if someone is trying to install a switch in any other position other
> than vertical, that will be between them and the inspector.
>
> Hope this helps.
>
> Eric
>
> ____________________________________________________________________________________
>
> Eric Bentsen  |  Schneider Electric   |  Solar Business  |   UNITED STATES
>  |   Technical Support Representative
> Phone: +(650) 351-8237 ext. 001#  |   Email:
> eric.bentsen at schneider-electric.com  |  Site:
> www.schneider-electric.com/solar   |   Address: 250 South Vasco Rd.,
> Livermore, CA 94551
>
>
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