my 220V outlet is measuring 360V??

[Brian Loran]

Is my multimeter bad (seems to work on other circuits)? How would it even be possible to get 360V?

[Carroll Courtney]

Make sure your battery is good,and not under voltage.----Carroll

[Brian Loran]

That must be it. Haven't changed the battery in years on this thing... don't have a 9V to confirm but I measured some 110V house outlets and they are all high too (180V). strange.

Thanks Carroll!

[John Coloccia]

Assuming it's not your battery or MM, measure each leg on the 240V outlet to ground. They should both measure 120, or thereabouts. If they do, then you're meter's acting up or you're doing something wrong. There should be no way to get 360V even measuring peak to peak as opposed to RMS. It is suspicious to me, though, that 360V happens to be 240 away from 120.

edit: nevermind. I thought you had said that your 120V outlets were measuring OK.

Actually, I thought about this again. Peak to Peak, if that's what you're measuring somehow, would be very close to 360V....about 340V. Maybe you have your meter set to measure that somehow? I don't even think my Fluke does that, but who knows? I do believe mine will measure Peak, though, but it's pretty obvious if you're setting it to do that. I would never do it again and again, by accident.

[Darrin Vanden Bosch]

Multimeters need to be calibrated every so often. This is what this sounds like. If it was accurate you'd have a lot of fried electronics in the house.

[Chris Studley]

I have managed the calibration for all sorts of DMMs, o-scopes etc and have never had a meter come back from calibration that bad. Maybe a volt or two off at most, and even that is quite rare. Measuring AC voltage can give some pretty weird readings of you aren't aware of the circuit and how it works or if the meter isn't set up correctly. I would presume the latter. My Fluke will measure peak/peak and is one of the selections available when set to measure AC. If it was the battery I wouldn't expect consistent measurements or the same +50% when measuring 120 vs 240v. I would measure something DC such as a battery or the output of a DC supply. Since DC is not a sine wave the voltage is the peak voltage and I would expect a more accurate measurement.

[Dan Hintz]

Are you measuring it as RMS or peak? If you're measuring as peak, you will read 170V (give or take, depending upon local conditions) from a 120V socket.

[Dennis Ford]

Is this one of those meters that Harbor Freight gives away free during promotions? If so, throw it away before it causes you much more trouble than the meter cost.

[ian maybury]

Sounds suspiciously like maybe you could somehow be measuring the voltage between two phases on a 220V/phase 3 phase system. The phase to phase (3phase) voltage is sq rt (3) x phase to neutral (single phase) voltage. Sq rt 3 = 1.732, so a 220V/phase system could be expected to give 220 x 1.732 = 380V

Be careful, if that's a genuine 360/380V you are seeing it's probably enough to kill you should you be unlucky enough to get a 'tickle' as it used to be called over here back in the day. You need a meter designed to read up to at least that sort of voltage.

Failing that there are some fancy three phase multi meters with all sorts of fancy measurement functions that I'm not familiar with. I wonder if its possible that you have one of those, and that it's on a setting that for some reason multiples the voltage reading by sq rt (3)?