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

Mon Nov 11 11:49:51 PST 2013

Hi Wrenches,
 There is no "implication" other than confirming how the disco 
is tested, and thus certified. It probably makes no difference 
electrically which position the
 unit is mounted, but AHJs may have differing opinions on whether this 
would be permitted. 
Rgds,
_____________________________________________________________________________________ 

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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From:
Bob-O Schultze <bob-o at electronconnection.com>
To:
RE-wrenches <re-wrenches at lists.re-wrenches.org>
Date:
11/11/2013 10:09 AM
Subject:
Re: [RE-wrenches] Square D Disconnects mounted on the slope of the roof.
Sent by:
re-wrenches-bounces at lists.re-wrenches.org

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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