Just a minor point: the dash-two appendage brings a wet-rated wire from 75 deg C to 90 deg C.
If you are not in a locale that argues for wet-rated wire and your specific application does not argue for wet-rated wire, IMHO it is perfectly acceptable to use THHN wire (90 deg C rated for damp environments) for outdoors, attics and other extreme temperature conditions. Of course you have to use good 3R boxes and rain-tight EMT connectors. For us, it is easier to purchase and inventory just one wire type for conduit runs, and we usually get the same price for THWN-2 as we do for THHN, or close enough. In fact we almost never use #12 either for the same reason. Peter T. Parrish, Ph.D., President California Solar Engineering, Inc. 820 Cynthia Ave., Los Angeles, CA 90065 CA Lic. 854779, NABCEP Cert. 031806-26 peter.parr...@calsolareng.com Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885 ________________________________________ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar Sent: Friday, July 23, 2010 10:04 AM To: RE-wrenches Subject: Re: [RE-wrenches] #10 THWN-2 Mick, -2 means 90 degrees C rather than 75. THWN-2 thus means that it is wet-rated at 90C. That is generally considered Code for arrays, such as if it is run in NM flex conduit to a traditional module j-box. The j-box area may be considered to be able to get hot enough to require 90C rated wire. Nowadays with MC-type module leads, combiner boxes aren't subject to the same high temperatures on the THWN as when they terminate in module j-boxes, and the higher temperature rating isn't generally necessary. Much of what I'm saying here is older John Wiles stuff. Allan Allan Sindelar al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com On 7/23/2010 10:52 AM, Mick Abraham wrote: I'm sorry to broadcast my ignorance, but: Could someone explain to me the significance of the -2 marking? Reply off-list if you wish to save bandwidth...but other List members may also be wondering... Thanks, Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 On Fri, Jul 23, 2010 at 10:48 AM, Nick Soleil <nicksoleilso...@yahoo.com> wrote: I have specified THWN-2 for years, but occasionally will not be able to source it! Sent from my iPhone On Jul 23, 2010, at 11:37 AM, "Peter Parrish" <peter.parr...@calsolareng.com> wrote: We went through a similar problem with some beach communities here in SoCal. Because of the high humidity (all winter and summer mornings) they wanted THWN-2 for all conduit runs (as well as PVC instead of EMT). At first we were charged a premium for THWN-2 compared to THHN. But then we found a source at All Phase Electrical Supply Burbank CA (a part of CED) for THWN-2 #10 stranded @ $162.40/k-ft. Brand is En(m?)core Wire. THWN-2 listing is printed on the insulation. - Peter Peter T. Parrish, Ph.D., President California Solar Engineering, Inc. 820 Cynthia Ave., Los Angeles, CA 90065 CA Lic. 854779, NABCEP Cert. 031806-26 peter.parr...@calsolareng.com Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885 _______________________________________________ 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 _______________________________________________ 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
