On May 27, 3:54 am, John Ross wrote:
dpb wrote:
John Ross wrote:
I have a 20 year old washer in the garage next to the dryer. In
between them there is a three prong outlet that the washer is plugged
into (the dryer, of course, has it's own).

The plug on the washer is two prong. ...[but] on the back is a wire ... with a little
flat connector thingy that I assume is the ground wire!

My guess is that this was done so if you had a two prong outlet that
was groundable by the plate screw, you would be able to use the washer
by screwing that end of the wire to the screw on the plate. Is that
correct? Is that a common thing (at least back then)?

This is an early '60s house with some grounded outlets, but most not.
Funny enough, the one there is a 3 prong one. So if I connect that
wire to the screw on the 3 prong outlet, will it be grouned?
...

Good guess, you're correct and yes, at least moderately common...

Well, at least the odds are good that the grounded outlet receptacle
is on a grounded circuit, but check to make sure -- a previous owner
could have replaced a two-prong outlet w/ a 3-prong one simply for the
convenience of having the place to plug in a 3-prong cord.

If it does have the ground wire, and a metal box (likely given age,
but plastic is still possible), then if the ground wire from the
circuit is properly attached, the box will be grounded and the plate
screw will suffice. If it is plastic box, that won't work as the box
will isolate the mounting strap and you'll have to arrange a jumper to
somewhere else. If the water piping is metal and is the house
grounding as would be pretty common in that time frame, then a clamp
around the nearest pipe would suffice.

It's not a danger _unless_ there's a failure somewhere that allows a
hot conductor to make contact w/ the frame -- that's the purpose of
the ground.

I forgot to mention 2 things:

1. There is another plug on the receptacle (this one is a normal 3
prong one). Does having that ground wire attached to the screw and
having this other one plugged in normally cause any problems?

2. The washer plug is the one removed in the garage when some tool
needs to be plugged in. So, with the washer 2 prong plugged in plus
it's separate ground wire screwed on the plate screw, when I unplug
the washer plug the ground will still be connected. If I then plug in
something else with a 3 prong plug, is that a problem? In other words,
I want to be able to unplug the washer plug, but now the ground to the
washer will be permanently attached to the outlet (and still there
when something else is plugged in).

No and no...leaving grounds connected is not a problem electrically.

Sounds as if would be convenienent to add another grounded outlet,
though. Or, if this is surface mounted, replace the duplex box w/ a
quadplex and the second outlet there might not be difficult.

In general, though, having the tool outlet in the neighborhood of the
washer/dryer station sounds like an inconvenience well worth relieving
unless you simply don't use an electric tool more than once or twice a
year.