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Bend Radius #176303 03/28/08 11:39 PM
Joined: Oct 2000
Posts: 3,636
Admin Offline OP
How come Square D can violate the minimum bending radius rules and we can't?

Is there some exemption for manufacturers? I must admit, it's a pretty bend, probably done on some hydraulically operated jig at the factory.

Linda Evans

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Re: Bend Radius [Re: Admin] #176372 03/30/08 03:36 PM
Joined: Mar 2004
Posts: 391
BigJohn Offline
What is this equipment? No phase identification either?

Last time I saw bends even remotely close to those, the tool that had made them had also destroyed the insulation. I wouldn't be too happy to open a cabinet and find that.


Re: Bend Radius [Re: BigJohn] #176374 03/30/08 06:08 PM
Joined: Oct 2004
Posts: 53
InspectorE Offline
Sorry about not giving more info. This is a Square D service entrance box (meter on left half) with 2 - 200 amp main circuit breakers in the right half. This is how it came from Square D. That's why I question why Square D can do this with a listed item. The insulation isn't broken on any of the 90 degree bends, I looked very carefully.

Re: Bend Radius [Re: InspectorE] #176389 03/30/08 11:35 PM
Joined: Feb 2004
Posts: 1,437
Lostazhell Offline
It's not just Square D... I've seen the same in Cutler Hammer, Siemens, Allen Bradley, Furnas panels and MCC's out where I work..... UL governs safety of equipment, NEC governs safety of it's installation

Re: Bend Radius [Re: Lostazhell] #176392 03/31/08 08:54 AM
Joined: May 2005
Posts: 984
ghost307 Offline
This looks like single conductor building wire with 600VAC insulation.

Which mimumum bending radius rules are they violating?

Re: Bend Radius [Re: ghost307] #176477 04/03/08 06:32 AM
Joined: Mar 2005
Posts: 1,213
SteveFehr Offline
They can do this because they test it like that, and it passes. They can do a lot of other things that are illegal per NEC, too, for the same reason- smaller conductors, for instance. NEC is rather conservative, as we all know.

So, don't look at it as exceeding the bend radius for cable, look at it as insulated cylindrical busbar!

Re: Bend Radius [Re: SteveFehr] #176478 04/03/08 07:09 AM
Joined: Dec 2004
Posts: 329
IanR Offline
Well put, Steve.
Remember the NEC has to be a very conservative catch all for many unseen installation parameters, that may or may not happen. The manufactures of these panels can test these units under controlled conditions. Then they specify the conditions, that these panels are used under, by listing them that way.

Re: Bend Radius [Re: IanR] #176482 04/03/08 09:20 AM
Joined: Oct 2004
Posts: 53
InspectorE Offline
"insulated cylindrical busbar"

I like that definition, maybe 2011 NEC will have it. Reminds me of the euphemism we used in the Army "aggressive retrograde maneuver" for run like hell.

Big difference between NEC and UL listing, ditto what the power company can do on their side of the meter.

Thanks folks!

Re: Bend Radius [Re: InspectorE] #176503 04/04/08 10:25 AM
Joined: Oct 2002
Posts: 482
Zapped Offline
This is the norm for the internal wiring in meter/load-center pedestals. I have never encountered a problem resulting from this type of installation.

Re: Bend Radius [Re: ghost307] #176723 04/10/08 12:00 AM
Joined: Aug 2001
Posts: 599
Nick Offline
Originally Posted by ghost307
This looks like single conductor building wire with 600VAC insulation.

Which mimumum bending radius rules are they violating?

I am with ghost. For under 600V what section is being violated??


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