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Several times, I felt some tingling when using my 30 year old grounded sawzall. Brand is Milwaukee. I thought that was odd since it has a grounded cord, plus I was wearing hiking shoes with thick rubber soles.

I investigated the non-gfci outlet (in the garage) with a multimeter. I was able to get ~110 volts across the two blade ports, but unable to get any voltage across either blade port and the roundish ground port. I tried the same thing on a kitchen GFCI outlet and was able to get a voltage across one of the blade ports (the small one if I recall correctly) and the roundish ground port.

I found a nearby outlet in the house with a good ground, and used it to finish the 5 minute sawzall project, but still stuck to gripping the sawall only by the red plastic handle the black rubber boot.

I haven't determined which circuit breaker controls the receptacle, or if other recptacles on the circuit have functioning grounds.

I think the multimeter results mean the ground is not working on garage receptacle. Is that right? how do I track down the problem? Does the tingling also mean I have an electrical problem within the sawzall?

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  • Does the saw have a two or three prong plug? Is the saw plastic, or does it have metal parts?
    – Tester101
    Commented Sep 18, 2017 at 15:40
  • 3 prong. metal body. 1/8" black rubber boot covering the head. Red plastic handle. It is 30 years old. Looks like these duckduckgo.com/… The grey portion is metal. Gripping it with one hand led to tingling.
    – David
    Commented Sep 18, 2017 at 15:43
  • Gripping [the grey metal] with one hand led to tingling
    – David
    Commented Sep 18, 2017 at 15:55
  • Get an ohmmeter/multimeter/continuity tester. With the tool unplugged, place one test lead on the smaller (hot) prong of the plug, and the other on the ground pin. Then pull the trigger on the tool. Repeat the same test, but place the second lead on the metal body of the saw, instead of the ground pin. If you get a reading on the meter in either test, you have a ground-fault in the tool.
    – Tester101
    Commented Sep 18, 2017 at 18:48
  • David, are you creating a new user account for each question? Please don't do that. Ask and admins can merge the accounts.
    – Harper - Reinstate Monica
    Commented Sep 19, 2017 at 1:31

1 Answer 1

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The taller blade is neutral.

Ground should be bonded to neutral at the main panel so a measurement from hot to ground should be near 120V... and a measurement from neutral to ground should be near 0v.

I agree a hot-ground reading of nil indicates no proper ground. To find that, you have to go chase the wires. Follow the wires back to the panel, find the last place ground is good, and open up that box and each subsequent box and see what is amiss. It super helps to know what normal looks like, so hit the books.

As for detecting a ground fault in the tool, try plugging it into a properly grounded** GFCI receptacle, get an insulated wire with bared ends, attach one end to a solid ground, and the other against metal parts of the saw.

Sometimes you can clear a tool ground fault by cleaning it well, or by disassembling it and cleaning it.

You really do want GFCI protection in garage and workshop space, though. If you don't have a ground, you may be better off getting a GFCI than a ground. GFCIs do not require ground. Learn how to use the LOAD terminals on a GFCI and you will only need one per circuit.

** GFCIs do not require ground, and grounding a GFCI is nice but it doesn't massively improve its safety. In this case I want you to use a grounded GFCI as a diagnostic aid, because it will help detect ground faults in a grounded tool.

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  • Wouldn't it be safer to check for a ground-fault using an ohmmeter, while the tool was not plugged in?
    – Tester101
    Commented Sep 18, 2017 at 18:44
  • 1
    @Tester101 - depending on the nature of the fault an ohmmeter might not find anything. A megger on the other hand probably would, but it's unlikely the OP has one (since if he did, he probably wouldn't be asking here).
    – brhans
    Commented Sep 18, 2017 at 20:12

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