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?
Thanks Bonnie
Yes and Yes
B_ snipped-for-privacy@hotmail.com wrote in news: snipped-for-privacy@4ax.com:
Question is does it need 3 prong? Can you determine if the tool itself is "double insulated". If so, that may be why it only has two prongs.
IIRC, most power tools with two prog plugs are double insulated. That means grounding the case doesn't buy you much.
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?Yes
Two prong plugs are polarized and are grounded to the neutral line.
On 11/16/2010 9:40 AM LSMFT spake thus:
No, not necessarily. My Craftsman circular saw, f'rinstance, has a non-polarized 2-prong plug, 'cause it's double insulated. No need for polarization.
How old it that? drop it in the bath tub and see how double is insulated it is. I wouldn't think they would stop making polarized plugs for power tools but what do I know.
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. But Having another place to put your hand on ground may not make the SHOP safer. Bottom line, safety is a SYSTEM problem.
On 11/16/2010 10:44 AM LSMFT spake thus:
About 25 years.
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" part.
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.
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.
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 carrying conductor.
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 solution.
They are never grounded to the neutral line.
With a polarized plug the switch is in the hot wire.
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.
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