Hi Kelly and William,
Certainly NEC 250.64(E)(1) requires ferrous metal raceways containing a GEC to be bonded at each end. 250.97 requires us to assure that we maintain electrical continuity of raceways and metal sheaths to ground. As far as I can tell this includes both ends of the raceway. William, if you have a concentric knockout on one side I would think that you do have to use a bonding bushing for that side and then using a grounding locknut on the other side. At least that’s what our inspectors in San Francisco seem to think. Kelly, do you have any code section you can point to which shows that bonding one side of the conduit is sufficient for circuits over 250 V to ground with a EGC? Best, August *From:* RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *William Miller *Sent:* Monday, July 14, 2014 10:47 PM *To:* 'RE-wrenches' *Subject:* Re: [RE-wrenches] Concentrics at 250 volts plus Kelly: Just as I suspected. I wish you could be here to share the lunch I have earned on my bet. Thanks, William [image: Gradient Cap_mini] Lic 773985 millersolar.com <http://www.millersolar.com/> 805-438-5600 *From:* RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org <re-wrenches-boun...@lists.re-wrenches.org>] *On Behalf Of *Kelly Larson *Sent:* Monday, July 14, 2014 10:16 PM *To:* RE-wrenches *Subject:* Re: [RE-wrenches] Concentrics at 250 volts plus Hi William, The requirement for bonding on BOTH ends comes when the wire though the conduit is a GEC. For EGC, just one end of the conduit is sufficient. Blessings, Kelly ~~~~~ Kelly Larson 707-223-3209 Box 504 Ukiah, CA 95482 Electrical Engineer NABCEP Certified Solar PV Installation Professional IREC Certified Master Trainer for Photovoltaic Installer CA Electrical Contractor# 868189 SolarKelly.com On Jul 14, 2014, at 3:11 PM, William Miller wrote: Friends: Please help us settle a crew debate before we come to blows: for circuits 250 volts and higher, do we need to bond EMT at both ends? Or, if there is bonded cabinet with a concentric on one end and a solid, bonded metal cabinet on the other, do we need a bonding bushing on the concentric end? I say a conduit needs to be bonded only on one end. My misguided employee says both ends. Both cabinets are independently bonded. Thanks in advance. William Miller Solar _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
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