Fellow Wrenches:
Per NEMA Standards Publication 250-1997 "Enclosures for Electrical
Equipment (1000 Volts Maximum)", a NEMA 3-R enclosure is designed
to provide a DEGREE of protection against 45 degree angled rain.
When testing for compliance, there can be no significant amount of
water within the enclosure and no water may be present on live
parts.
NEMA 250 states is Section 4.4 ENCLOSURE ORIENTATION:
If the acceptability of a Type 2 or 3R enclosure is
dependent upon a particular mounting orientation, the
enclosure shall be marked to indicate the required orientation
unless the mounting is obvious.
If a Type 2 or 3R enclosure has knockouts for conduit in
the sides or back of the enclosure in which the
equipment to be installed is not known, it shall be marked to
indicate the area in which live parts are to be
installed.
The spec sheet for a NEMA 3-R Square-D safety switch states that
"Device Mounting" is "Surface". I would interpret that as
vertical. Also, a vertical orientation of the enclosure would
minimize the amount of water intrusion from a 45 degree angled
rain test.
Regards,
Gary Willett
Icarus Solar
On 11/11/13, 1:49 PM, eric.bent...@schneider-electric.com wrote:
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.bent...@schneider-electric.com
| Site:
www.schneider-electric.com/solar
| Address: 250 South Vasco Rd., Livermore, CA 94551
*** Please consider the environment before printing this e-mail
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.bent...@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@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
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@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
______________________________________________________________________
This email has been scanned by the Symantec Email
Security.cloud service.
______________________________________________________________________
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@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
|
