I'm adding a couple of outlets in my kitchen, and using metal boxes.
Does the short insulated green wire which grounds the outlet to the
box HAVE to be solid to comply with the electrical code? I don't have
any solid green wire on hand but I've got a whole spool of 12 Gauge
green insulated stranded copper wire.
I know a foot or two of solid green wire is not a major expense. I
just hate to drive to Lowes' if the stranded wire I already have is
Dumb question- why does code now require that little jumper wire? From
the time grounded residential wiring became normal (late 50s to early
60s?), to the time I quit hanging around on active construction
sites(late 70s), SOP was metal boxes, with the bond wire wrapped around
the romex jacket and captured under the metal strain reliefs. Outlet was
grounded by virtue of the metal device ears being screwed directly to
the metal box ears. When and why did that stop being good enough any more?
It was around that time that grounding receptacles became the code, and the
Nec decided that the undersized copper wire in the romex should become equal
sized and have a proper termination to the box. I suppose at the same time,
they felt that the attaching screws of receptacles weren't adequate for
grounding purposes, and introduced the grounding conductor pigtail. Today,
there are a number of acceptable methods including self-grounding
receptacles, which have a small spring that contacts the attaching screws
for better conduction
It is legal to skip the screw if this is a "handy box" and the device
is made up tight to the box. Some AHJs also want the fiber washer
The real problem comes with boxes recessed in the wall. Then the
device may not be tight to the box, it is probably really just tight
against the drywall hanging on the ears and when the drywall relaxes a
bit it is not tight to the screws. They do make a self grounding
device that grips the screw with a spring.
The other problem is a lot of boxes are plastic these days.
I am not aware that was ever code compliant. Certainly isn't now.
It is required that at least one fiber washer be removed (250.146-A).
For a raised cover with a receptacle for a 4x4 box, you used to be able
to use the single cover screw on the receptacle for grounding. Now you
need 2 screws from receptacle to raised cover. They have to have a
"thread locking" or "screw locking means" (I never figured out what that
Long ago they started putting "bonding screws" on the boxes -
pinching the ground under the clamp is a very poor quality ground
connection. As for the ground, by code it does not need to be
insulated, and if uninsulated does not need to be green.
If bare wire is used, make sure it stys on the neutral (white wire)
side of the outlet.
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