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Strain relief on drop cords.

Posted By: Joe Carpenter

Strain relief on drop cords. - 05/21/02 05:09 PM

In an industrial setting. 30amp 480volt Flexible Drop cords to supply power to machinery. These Cords must have Strain relief at the top.
My question, must the twist lock plugs which are located 6' off the floor also have special strain relief built in?
400.10 in the 2002 NEC does not go into a lot of detail.
What's your take?
Thanks
Posted By: rmiell

Re: Strain relief on drop cords. - 05/22/02 02:33 AM

Joe, are you asking if the female end of the hanging cord needs strain relief? What strain would be imposed on the cord cap? Just the 6' cord from the unit?

I would think the strain relief on top will protect the cord from damage while hanging. The twist-lock plug and cap will not have much strain, at least not enough to damage anything.

What's your thoughts on this?

Rick Miell
Posted By: Joe Carpenter

Re: Strain relief on drop cords. - 05/22/02 10:24 AM

Yes, that was my question. I did'nt think it would be an issue although I recalled seeing strain reliefs on the female plug in several factories. It may have been a policy within the factory or perhaps the local AHJ specified them.
Posted By: Redsy

Re: Strain relief on drop cords. - 05/22/02 10:36 AM

I have seen strain relief where an outlet box was hung at the bottom of the cord drop. But I imagine the cord caps clamp would be adequate in your case.
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