Drop cord confusion

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sfav8r

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OK, I thought I knew what I was doing (first mistake) but after reading a few other posts, now I'm not sure. We're putting in 12 drop cords in an office space. The plan was as follows:

Install 12 4 Square metalic boxes flush with the drop ceiling. These will be supported with unitstrut from the concrete ceiling above. We will install SO cord on twist-locks and use pendant rated boxes at the base. The plan was to use a strain relief (Amtec) attached to the 4 sq box.

The purpose of the drops is to service a group of tables in the center of the room. The tables are not moved real frequently, but the owner wants to have the option of moving them around somewhat.

Does this comply with NEC? Specifically 400.7 and 400.8. I thought it did, but in other posts some have felt that it is a violation of 400.8(4) because the strain reliev attaches the cord to the building. I always thought that section was referring to attachment to the building such as stapling it along a wall. I can't imagine why it would be a violation to attach a strain relief. Any thoughts on this fine point or any other part of the installation?

Thanks
 
Why not simply install twist-lock receptacles in the 4" ceiling boxes, and make up cords that can be relocated as needed?
 
LarryFine said:
Why not simply install twist-lock receptacles in the 4" ceiling boxes, and make up cords that can be relocated as needed?
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That's what we are doing:

"Install 12 4 Square metalic boxes flush with the drop ceiling. These will be supported with unitstrut from the concrete ceiling above. We will install SO cord on twist-locks and use pendant rated boxes at the base."
 
The Iceman said:
Not sure but are you going to be in violation of 400.8 (2)? If you are installing SO in a suspended ceiling I think you are.
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I think that only applies to cord ABOVE the suspended ceiling. We are using the SO as drop cord. The boxes that are flush with the ceiling are feed with flex. The SO has a twistlock and drops from the box. There will be a strain relief that attaches to the metal box.

Thanks.
 
IMO your okay. If you can't attach a strain relief to a box mounted on a ceiling or elsewhere on the building where would you use one? Its going to be attached somewhere. IMO there is no difference in hanging it from a 4" square box or say a bus duct switch for example. As far as the attachment plugs go I work in plants where there are hundreds of the yellow type hubbell outlet boxes hanging from the yellow 12/3 cord and 1/2 hub strain relief at the 4" square above. No attachment plug. Is this a violation? I have electricians and inspectors say yes and no. Maybe we can get some of the inspectors here to give their opinion.
 
teco said:
IMO your okay. If you can't attach a strain relief to a box mounted on a ceiling or elsewhere on the building where would you use one? Its going to be attached somewhere. IMO there is no difference in hanging it from a 4" square box or say a bus duct switch for example. As far as the attachment plugs go I work in plants where there are hundreds of the yellow type hubbell outlet boxes hanging from the yellow 12/3 cord and 1/2 hub strain relief at the 4" square above. No attachment plug. Is this a violation? I have electricians and inspectors say yes and no. Maybe we can get some of the inspectors here to give their opinion.
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Anywhere I have done industrial, I have never been cited for it. It was applied quite efficienty. Twist-Lok that is.
 
teco said:
IMO your okay. If you can't attach a strain relief to a box mounted on a ceiling or elsewhere on the building where would you use one? Its going to be attached somewhere. IMO there is no difference in hanging it from a 4" square box or say a bus duct switch for example. As far as the attachment plugs go I work in plants where there are hundreds of the yellow type hubbell outlet boxes hanging from the yellow 12/3 cord and 1/2 hub strain relief at the 4" square above. No attachment plug. Is this a violation? I have electricians and inspectors say yes and no. Maybe we can get some of the inspectors here to give their opinion.
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where does the strain relief get attached at the box? - a cover with a knockout or a knockout on the box?
 
A bit out dated but I thought this was a good article on flexible cords and fixture wires.
http://ecmweb.com/mag/electric_cords_fixture_wires/

404ecm17fig2.jpg
 
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