Stripped Ground Screw

Attempting to connect two #14 ground wires to a single ground screw in single-tube Lithonia fluoresecent fixtures joined end-to-end resulted in stripping the screw threads in the sheet steel fixture. Is it acceptable to substitute the next larger size of self-tapping machine screw. Of course it won't be green and will be cadmium or zinc plated.
Alternatively, a longer ground might be screwed through a nut on the backside of the fixture but this would be inconvenient.
David Merrill
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David Merrill wrote:

Of course.
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You mean, of course NOT. Two wires under one screw is a Code violation except where the terminals are specifically listed for multiple wires.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Either one. The bare copper wires are indication enough that it's a ground.
R
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Maybe. No requirement for it to green. There is a prohibition on the use of sheet metal screws for grounding and bonding. There is also a variety of opinions on whether a self tapping screw is the same as a sheet metal screw. The way the code is written it could be interpreted that any screw other then a "sheet metal screw" would be acceptable (i.e. drywall screw, wood screw, etc.) I am not sure that was the intent.
2005 NEC
250.8 Termination of Grounding and Bonding Conductors Equipment grounding conductors, grounding electrode conductors, and bonding jumpers must be terminated by exothermic welding, listed pressure connectors (set screw, compression), listed clamps, or other listed fitting. Sheet-metal screws shall not be used for the termination of grounding conductors. Note: If a screw is used for grounding that screw shall not be used for any other purpose.
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Next size up is acceptable. It doesn't have to be green.
However -- the unacceptable part here is trying to put two wires under one screw. Code prohibits connecting multiple wires to a single terminal unless the terminal is specifically approved for multiple wires -- and you just discovered one of the reasons why.
So for this one, and to avoid similar problems on other fixtures in the future, loop a short (6" or so) pigtail around the grounding screw, and wire-nut it to the two #14 ground wires.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Exactly the information I needed. Thank you all.
David Merrill
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