Cover mounted receptacles

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farmaped

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Engineer
I searched for this but could not seem to find a definitive answer. IAW 250.146(A), mounting a receptacle to a metal raised box cover via two (2) screw & locknuts (through the receptacle top and bottom yoke), and mounting (screwing) this raised cover (on its flat - non-raised portion) to a grounded metal box DOES or DOES NOT require a bonding jumper from the from the grounded metal box to the receptacle?
2011 Handbook, Exhibit 250.57 reinforces my interpretation of 250.146(A) that a bonding jumper IS NOT required. Or am I full of salt?
Thanks
 
If the surface of the cover is all flat then a bonding jumper is required. If there are dimples in the corners where the mounting screws would be installed then a bonding jumper is not required. That's because the dimpled cornered covers are already listed for grounding the device due to the UL standard for those style covers.
 
250.146 (A)
(A) Surface-Mounted Box. Where the box is mounted on the surface, direct metal-to-metal contact between the device
yoke and the box or a contact yoke or device that complies with 250.146(B) shall be permitted to ground the receptacle to
the box. .......... A listed exposed work cover shall be permitted to be the grounding and bonding means when (1)
the device is attached to the cover with at least two fasteners that are permanent (such as a rivet) or have a thread locking or
screw or nut locking means and (2) when the cover mounting holes are located on a flat non-raised portion of the cover.
 
You guys read past the important part. "This provision shall not apply to cover mounted receptacles unless the box and cover combination are listed as providing satisfactory ground continuity between the box and the receptacle."
 
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