On 07/07/2010 02:00 PM, bud-- wrote:
Josh wrote:
But is that circuit correctly grounded, is it?????

When I bought the 50s vintage house in 1971, all the outlets were the
old 2-prong type. The only ground was outlet ears and/or outlet
mounting screws into the metal outlet boxes and back to the breaker
box via the flexible armored steel conduit. Over the years I've
replaced all the outlets with 3-prong type, drilled a hole in the back
of the outlet box for a sheet metal screw, and connected a 6 inch
green 12 gauge wire from the screw to the outlet ground connector.
That's the case with the garage outlet I'm modifying from single to
double.

The NEC would like you to use a screw with machine threads, at least 2
threads in the metal (250.8). (Typically 10-32.)

Klein makes a nice "multi tap" that is a 6-in-1 tap on a screwdriver
handle, perfect for this app. Shoot a hole in the back of the box and
then tap it to 10-32 with the multi-tap, green screw, pigtail of bare
14AWG, et voila.

Only works if the box is already grounded, of course.

nate


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