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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Brian Adams on March 12, 2016, 04:21:01 PM
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A broadcast station I work with recently purchased a new TV production truck from a well known vendor for this market segment. Included with the truck are several looms of single conductor 1ga welding cable to be used as feeder cable for the 100A service. I've advised them that welding cable isn't rated for this use, especially since the cable will be used outdoors and in public areas. The broadcast station agrees with my assessment, but the truck vendor refuses to replace the cable with something better. Their response was essentially, "we've been doing it this way for 40 years and no on has ever had a problem with it."
What are the relevant codes that specify the cable types that you're allowed to use for this sort of thing? And what are the codes that disallow using welding cable as feeder? I'd like to be able to go back to the vendor with real information instead of just my rudimentary understanding of the subject, and hopefully get this cable replaced with something more appropriate.
FWIW, they used the same welding cable within the truck for the feed from the connector panel to the distribution box. I don't think this is a big deal since it's all enclosed, but hopefully someone will let me know if I'm wrong about that.
I'll appreciate any insight anyone can provide me on this topic. Thanks in advance.
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I'll appreciate any insight anyone can provide me on this topic. Thanks in advance.
Yeah, we all used welding cable 30 or 40 years ago, and got away with it, but those days are over.
The broadcaster I work for found out the hard way at Expo 86 in Vancouver (30 years ago) that the mobile trucks would not be connected to venue power unless the welding cable was replaced with "entertainment" cable. Back then, hardly anybody had heard of it, but the electrical inspector was adamant.
Sooner or later, you'll be in the same situation, and find yourself scrambling to get power.
GTD
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Type S, SO, SC, W are all listed in the NEC as suitable for single conductor portable switchboard feeder.
At our PAC I am not allowed to connect welding cable to the building service, not am I allowed to connect it to a generator placed on city property.
I'm not sure if the county arena has a similar policy but it's managed by SMG, who *does* have "best practices" work rules so I'd be surprised if non-compliant feeder was allowed
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The broadcaster I work for found out the hard way at Expo 86 in Vancouver (30 years ago)
I was at Expo 86. I was 7 years old, but my family and I went. In my grandparent's RV. Woo hoo!
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I rode my R100/7 from the Bay Area to Expo 86. Don't remember very many temporary carnival like set-ups there, more like a quickie Disneyland.
I think the OP is hoping for NEC chapter and verse he can go back to the offender with.
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Keep in mind that not all welding cables are created equal. Check the print on the outside of the cable and look up the spec. If there is no print, manufacturer, or cable type on the jacket/insulation, then go back at the vendor and let them know they need to supply cable has a rating on it.
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I rode my R100/7 from the Bay Area to Expo 86. Don't remember very many temporary carnival like set-ups there, more like a quickie Disneyland.
I think the OP is hoping for NEC chapter and verse he can go back to the offender with.
From the 2005 Code (what I have at home) -
Article 520.53 (H) Supply Conductors
(1) General. The supply to a portable switchboard shall be
by means of listed extra-hard usage cords or cables..... (snip)
Extra-hard usage cords and cables are listed in Table 400.4, under Trade Name "Hard Service Cord." Note that the trade name does not use the word "extra". Footnote applies: 4. Types G, G-GC, S, SC, SCE, SCT, SE, SEO, SEOO, SO, SOO, ST, STO, STOO, PPE, and W shall be
permitted for use on theater stages, in garages, and elsewhere where flexible cords are permitted by this
Code.
Also Article 525 may be applied by the local Authority Having Jurisdiction as it is frequently applied to anything set up outdoors (like a broadcast truck). The feeder requirements are the same (extra hard usage) with additional language regarding protection of cables in trafficked areas.
Article 640 is referenced in 520 primarily regarding the use of flexible cords and protection of cables.
Take into account that my copy of the code is 11 years old, and there have been changes and revisions since then but the gist of it remains the same: only types listed in the footnote are permitted for supplying portable switchboards.
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In case anyone is still interested, this issue is getting this resolved. The manufacturer of the welding cable, Southwire, indicated that their welding cable is only rated for welding, not for portable power distribution. The vendor is working on sourcing a suitable replacement, and is seriously rethinking the use of welding cable for future projects.
Thanks for your help everyone, I really appreciate your insight. The specific article numbers really helped in getting this situation resolved.
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In case anyone is still interested, this issue is getting this resolved. The manufacturer of the welding cable, Southwire, indicated that their welding cable is only rated for welding, not for portable power distribution. The vendor is working on sourcing a suitable replacement, and is seriously rethinking the use of welding cable for future projects.
Thanks for your help everyone, I really appreciate your insight. The specific article numbers really helped in getting this situation resolved.
...and good on you for pursuing it to a successful outcome!
iz