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

[Bob-O Schultze]

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 


_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Change email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org