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Are the concentric knockout in the Load centers, Metering or Safety Switches rated for grounding (or bonding) in accordance with the NEC, using a standard nipple or connector?

Issue:
Product Design Features

Product Line:
Load Centers, Safety Switches and Metering

Environment:
Knockout grounding

Cause:
Application

Resolution:
No. There is no test in the UL standards for these product lines, for the knockouts of the enclosures. The test for this requirement is found in UL 514A (Standard for Safety - Metallic Outlet Boxes) only. The enclosures for Load centers, Metering and safety switches are manufactured to the UL 50 standard. The installer MUST use a "Bonding Bushing" for such a connection or follow what the Code requires.
 
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