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Lighting & Electrical
NFPA decision on new section, NEC 445.20, for small (<15kW) portable generators
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<blockquote data-quote="Guy Holt" data-source="post: 129222" data-attributes="member: 7980"><p>Re: NFPA petition decision on 2014 NEC 445.20, for portable generators <15kW</p><p></p><p></p><p> </p><p>I spoke to someone who was part of the Code Panel 13 drafting of NEC 445.20. According to this individual, the requirement for GFCIs on 125V circuits on a generator where the 240V circuit is in use as well was discussed only in the context of the generator serving as home back up power. In that application the bond between the ground and neutral in the service head of the house will assure the reliable operation of GFCIs on the generator. The use of a generator in a stand-alone application as a separately derived system was never discussed. Even though this individual recognized the fact that in a stand-alone situation (without a Ground-Neutral Bond) GFCIs will not operate reliably and therefore not provide “equivalent protection”, NEC 445.20 as written will require their use none-the-less on 120V circuits in pro-sound applications when a “spider box” is used on the 240V receptacle and motion picture lighting applications when a 240V lighting load (like a 4k HMI) is used on the 240V receptacle. The only inherent danger here is that the false positive of GFCI test circuits in these situation (that I discussed above) will create a false sense of security in the user of the devices.</p><p> </p><p style="text-align: center">[ATTACH]10669[/ATTACH]</p><p></p><p>One approach that will satisfy the “equivalent protection” intent of NEC 445.20 is to use a transformer to step-down the 240V output to 120V instead of splitting it as a spider box does. </p><p> </p><p style="text-align: center">[ATTACH]10670[/ATTACH]</p><p></p><p>As a separately derived system, a transformer typically bonds neutral to ground to create a low impedance path (illustrated above <span style="color: #3E3E3E">(click on the image to enlarge it, then hit the back button to return to the forum.)</span>) for fault current back to the transformer windings thereby assuring the reliable operation of GFCIs. </p><p> </p><p style="text-align: center">[ATTACH]10671[/ATTACH]</p><p></p><p style="text-align: center"><strong><em>A cart outfitted with 60A Transformer/Distro, 100A Shock Block, and 4/2.5kw & 1800W ballasts. </em></strong></p> <p style="text-align: center"><strong><em>Note: that the 1800W Ballast is plugged directly into a 60A Woodhead w/3 20A circuits.</em></strong></p><p></p><p>If you add a breaker (as we do on the Transformer/Distros we make for the Honda EU6500 – pictured above) you have reliable over-current protection as well. </p><p> </p><p> </p><p>Guy Holt, Gaffer </p><p>ScreenLight & Grip </p><p><a href="mailto:rentals@screenlightandgrip.com">rentals@screenlightandgrip.com</a></p></blockquote><p></p>
[QUOTE="Guy Holt, post: 129222, member: 7980"] Re: NFPA petition decision on 2014 NEC 445.20, for portable generators <15kW I spoke to someone who was part of the Code Panel 13 drafting of NEC 445.20. According to this individual, the requirement for GFCIs on 125V circuits on a generator where the 240V circuit is in use as well was discussed only in the context of the generator serving as home back up power. In that application the bond between the ground and neutral in the service head of the house will assure the reliable operation of GFCIs on the generator. The use of a generator in a stand-alone application as a separately derived system was never discussed. Even though this individual recognized the fact that in a stand-alone situation (without a Ground-Neutral Bond) GFCIs will not operate reliably and therefore not provide “equivalent protection”, NEC 445.20 as written will require their use none-the-less on 120V circuits in pro-sound applications when a “spider box” is used on the 240V receptacle and motion picture lighting applications when a 240V lighting load (like a 4k HMI) is used on the 240V receptacle. The only inherent danger here is that the false positive of GFCI test circuits in these situation (that I discussed above) will create a false sense of security in the user of the devices. [CENTER][ATTACH=CONFIG]10669[/ATTACH][/CENTER] One approach that will satisfy the “equivalent protection” intent of NEC 445.20 is to use a transformer to step-down the 240V output to 120V instead of splitting it as a spider box does. [CENTER][ATTACH=CONFIG]10670[/ATTACH][/CENTER] As a separately derived system, a transformer typically bonds neutral to ground to create a low impedance path (illustrated above [COLOR=#3E3E3E](click on the image to enlarge it, then hit the back button to return to the forum.)[/COLOR]) for fault current back to the transformer windings thereby assuring the reliable operation of GFCIs. [CENTER][ATTACH=CONFIG]10671[/ATTACH][/CENTER] [CENTER][B][I]A cart outfitted with 60A Transformer/Distro, 100A Shock Block, and 4/2.5kw & 1800W ballasts. Note: that the 1800W Ballast is plugged directly into a 60A Woodhead w/3 20A circuits.[/I][/B][/CENTER] If you add a breaker (as we do on the Transformer/Distros we make for the Honda EU6500 – pictured above) you have reliable over-current protection as well. Guy Holt, Gaffer ScreenLight & Grip [EMAIL="rentals@screenlightandgrip.com"]rentals@screenlightandgrip.com[/EMAIL] [/QUOTE]
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NFPA decision on new section, NEC 445.20, for small (<15kW) portable generators
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