The code provisions regarding conductors in parallel [2011, 310(H)(I)] are very specific and make complete sense. When installed correctly, in larger sizes, 1/0 or greater, as permitted, there is very little likelihood of significant difference in resistance or any other problem. This is done safely and routinely every day all over the US and probably the world. In larger sizes there are substantial practical and economic advantages to using parallel conducors. In smaller sizes these advantages don't apply. The explanatory text in the Code Handbook explains this more completely than I can here.
Dick Ratico Solarwind Electric --- You wrote: Good points. I would think a more dangerous situation would be the case that you often have with large parallel feeders landing on a single OCPD. If one wire has a little less resistance, it will always run hotter than the other, and you could easily overheat a wire that is protected by that large OCPD. Thanks On Wed, Sep 26, 2012 at 6:48 AM, Jeff Irish <[email protected]> wrote: > Code issues aside, even two seemingly identical runs each with breakers > would have at least slightly different resistances, causing the lower > resistance run to take more than half the total current, tripping the > breaker in that run, then causing a tripping of the breaker in the other > run.**** > > ** ** > > Jeff Irish**** > > ** ** > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *mac Lewis > *Sent:* Tuesday, September 25, 2012 9:16 PM > *To:* RE-wrenches > *Subject:* [RE-wrenches] parallel OCPD**** > > ** ** > > Hello wrenches,**** > > ** ** > > Does anyone understand why you are not allowed to have parallel separately > protected runs of wire.**** > > For example, say I need 120A from point A to point B, why doesn't the code > allow two runs of #6 breakered at 60A each. Its probably obvious, but not > to me...**** --- end of quote --- _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] 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
