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Monday, March 30, 2015
Question:
Re: CQD answer published Tuesday, March 24, 2015
When connecting a metal conduit or cable to a nonmetalic enclosure, the proper term for the fitting would be a "grounding" fitting and not a "bonding" one.
The simple technique would be to use a grounding locknut. That has a binding screw connection for attaching a "grounding" conductor. A bonding fitting has a pointed screw on the locknut that facilitates bonding of the locknut to the metallic conductive box after locknut is fully tightened. This bonding locknut is used for conduits over certain trade sizes, 1-1/2" from memory so check, and raceways and conduits intervening between load center and hazardous classified areas.
Regards, Nick Abbatiello
A
Answer:
Hey Nick thanks for your comment it is an interesting point.
On page 263 of the 2014 UL White Book under Grounding And Bonding Equipment (KDER), Grounding and Bonding Bushings UL describes products that have a set screw as a bonding product and those that have a provision for a wire as a grounding product. The question was about the use of nonmetallic boxes so you are correct a product with provisions for a wire would be needed and UL calls that a grounding product. But the exceptions to 314.3 use the term bonding. Comparing the terms "bonded" (connected to establish continuity and conductivity) to "ground" (the earth) and "grounded" (connected to ground or something that extends the ground connection) in Article 100. Some make the point that both "bonding" and "grounding" is being done. I believe we are really doing a bonding function, each connection is establishing continuity and conductivity.