Hot Topics: I Have a Multimeter - But Am I Using It Wrong? Hot Topics: I Have a Multimeter - But Am I Using It Wrong?

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You’ve been using your tools your way long enough to be pretty comfortable, even if you’re self-taught. But when someone sees you with a multimeter and they freak out, it can rattle your confidence. Electricity is dangerous and just because you haven’t electrocuted yourself doesn’t mean you’re doing it right. Check in with the Forum to dial in your technique.

Original Post: Using a multimeter correctly?

Mikedel Member

Hi to all. Apologies for the "pre-kindergarden level" question.

I was at a neighbor’s… had a GFCI receptacle stop working, and asked me to take a look. It had gone bad, and we replaced it. Problem solved.

One thing: As I worked on this, it came time to see if there was power getting to the GFCI.
I used my analog multimeter - the way I have always used it - and my neighbor got all nervous/agitated/freaked out - he said "that can't be the way to do that; it's dangerous;” etc.
He was not being a jerk, just concerned for safety.

What I did that concerned him:

To test for power, I touched one of the probes(?) - (the needle like things at the ends of the multimeter's wires) to the black wire, the other to the white, and got my reading.

My question: Is that how you're supposed do it? If it is not the way to do it, how do you do it?

Thanks in advance.

Highlights from the Thread

Gunguy45 Super Moderator

That's the only way to do it! And of course, black to ground and white to ground also, just to be thorough. What did he expect, you just wave them in the air nearby? Most probes won't make good contact by sticking them in the slots. Pulling the receptacle out and touching the screws or wires is a much better test.

joecaption1 Member

That's the way to see if there's incoming power if you touched the line side. Need to be touching the load side to see if the GFI is working.

telecom guy Member

You did good Mike! I can't imagine a way of noncontact voltage measurement (not detection) that would even fit in a tool box!

AllanJ Member

Meter musings (quips, tips, kinks):

Always select the proper function and range before making a measurement. If you are not sure, set the voltage range to be as high or higher than what could reasonably could be on the wires - notably for household use start with at least 250 volts range. Repeat with a lower range if needed.

Always turn off the power before doing resistance (ohms) or continuity measurements. Generally resistance and continuity measurements are not useful unless at least one of the two places (wire, screw) you touch the meter probes to has everything else disconnected/unhooked from it.

“You did good Mike! I can't imagine a way of noncontact voltage measurement (not detection) that would even fit in a tool box! “

Voltage is always measured between two points, and in most cases one of those two points is supposed to be neutral.

Most persons should not measure voltage between two terminals on a switch. That does give information, but information that is totally useless to someone without a good amount of electrical know-how.

Mikedel Member

Once again, thanks to all.

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