William, the only explanation that I have found for using THWN-2 in conduit run through the attic is that during the day as the temperature in the attic increases, the air in the conduit expands, at night the opposite effect happens, the temperature in the attic decreases and the volume of air in the conduit contracts with the potential to bring in what ever climate conditions exist outside the conduit (In FL this could be humid air).
Over time if there is humid air present, this could form condensation in the conduit or NEMA 4 rated enclosure, hence the need for wire and connections rated for a wet location.
I have seen photos at inspectors meetings of NEMA 4 enclosures and conduit that contained water although I am not sure how often this would normally happen.
Jamie Johnson
NABCEP Certified PV Technical Sales Professional
NABCEP Certified Solar PV Installer
General Manager
NABCEP Certified PV Technical Sales Professional
NABCEP Certified Solar PV Installer
General Manager
SOLAR POWER ELECTRIC
-------- Original Message --------
Subject: [RE-wrenches] Wet locations: (was Push-in Wire Connectors)
From: William Miller <will...@millersolar.com>
Date: Fri, October 21, 2011 10:51 am
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>Friends:
I have had plan checkers insist I use wet rated wire on rooftops even though the wire was in either liquid tight or EMT with raintight connectors. I did not need to dispute this because we had specified THHN wire that is also rated THWN for wet locations. This discussion makes me think I should have contradicted the requirement because I am not sure wet rated wire is required inside dry conduit. I will be looking this up.
I feel that you should not let an AHJ impose a requirement that is not in the code because then you become bound to the new stricture. I realize that an AHJ can impose stricter requirements, but I insist that it be in writing, required in advance of the job in question and that it be required universally. Otherwise, it's anarchy.
William Miller
Miller Solar
Voice :805-438-5600
email: will...@millersolar.com
http://millersolar.com
License No. C-10-773985
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & 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 Options & 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
