I have some power equipment that needs a new cord.
The current cord has only 2 prongs.
Can I buy a 3 prong power cord and just attach the ground to the case
of the power tool? Is this what the 3rd prong does?
Would this make is safer?
Does a GFCI also work on a power tool with just 2 prongs?
If the insulation FAILS for any reason, it doesn't matter whether it
was originally single, double, triple insulated...
So, grounding should make THIS tool safer.
Having another place to put your hand on ground may not
make the SHOP safer.
Bottom line, safety is a SYSTEM problem.
So you OPEN the tool and MODIFY the tool's electrical safety system. Not
only does the warranty go "poof" but your heirs will play hell collecting
from the tool's manufacturer.
A double-insulated tool with a two-prong connector will be UL certified.
It's a tad presumptuous to think of improving on UL's standards.
re: -- Not only does the warranty go "poof" --
The OP said "I have some power equipment that needs a new cord."
I may be going out on a limb here, but I'm thinking that if the tool
needs a new cord, and the OP is planning on replacing it herself, then
the warranty is not at issue here.
Depends on how old the power tool is.
If it has a polarized plug it is almost certainly double insulated.
If it has a metal case the ground will make it safer - double
insulated tools as a general rule do not have metal cases.
The OP asked 4 questions but you only supplied 2 Yes's.
Shouldn't it be: Yes, Yes, Yes and Yes?
Actually, if we dig deeper, I think it should be: No, sort of, it
depends and Yes.
1 - Can I buy a 3 prong power cord and just attach the ground to the
case of the power tool?
No. Just attaching the ground wouldn't do much for you. You would also
need to attach the Hot and Neutral wires to their proper places. ;-)
2 - Is this what the 3rd prong does?
Sort of. The 3rd prong actually connects the grounding wire of the
power cord to the receptacle's groung lug. Correctly installed (the
cord, the plug and the receptacle), this should connect the
equipment's case to ground, which is the ultimate goal.
3 - Would this make is safer?
We would need a little more information before we can properly answer
"Would this make is safer?" It might...it might not. If the tool is
already double insulated, would a ground wire really make it safer?
4 - Does a GFCI also work on a power tool with just 2 prongs?
WTF? On just what planet is that the definition of double insulated?
The spec doesn't mean "can be thrown in bathtub or used in pouring rain
with no danger". It means all external parts of the tool are safely
isolated from either side of the line (hot/neutral)--that's the "double"
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.
Two prong plugs on modern tools are double insulated, don't have metal
housings and are not grounded to the neutral, which is a current
The answer to the original question is it depends. If it's an old
tool that is not double insulated and UL listed with a 2 prong plug,
then installing a new 3 prong plug and connecting the ground wire to
the metal housing might make it safer. But even that depends, because
we don't know how the tool is put together. For example, if there
were two seperate metal parts of the tool that are not connected
together, then you could be only grounding part of the tool.
In any case, a GFCI will work with it in any case and provide a safe
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