I just purchased at home built in 1922. It is obvious there has been some modifications to the electrical system. The only permitted change was upgrading it to a 200 Amp service. In trying to figure out the circuits I noted there were 4-240Volt breakers, three a 20 Amps and one at 30 Amps. All four were marked as "AC." There is only one (1) 240 Volt window unit, so in looking around I found three old 240 Volt outlets which are not being used. I first tested them with a voltage probe - they were hot, so I used my multimeter and it reads about 590 Volts, or when I measure one side it reads about 147.5 volts or so.

This has me stumped! Oh yes, I checked a 110 volt circuit and it reads about 147.5 volts. The 590 is 4 times the 147.5. Why am I getting that reading? Am I doing something wrong, is my meter nuts, or??

Either your meter is defective or you don't have it set up properly. Most likely the latter. Make sure you have the dial on ac voltage (probably has wavy line, not dashed line) and that you have leads plugged into the common and voltage ports.

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Originally Posted by hkstroud

Either your meter is defective or you don't have it set up properly. Most likely the latter. Make sure you have the dial on ac voltage (probably has wavy line, not dashed line) and that you have leads plugged into the common and voltage ports.

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Thanks! I thought maybe my meter was nuts too. Fortunately it's almost impossible to set the meter up incorrectly - I did check, and I've got it right. Guess I'll drop by Lowe's and replace this old thing. Hey, got any of those left handed widgets laying around? Needed one yesterday! :-) Thanks again.

Sorry, out of widgets at the moment but I do have a left handed monkey wrench. And it's a metric one too.

Morning Harold,

Darn, no more widgets - guess the angle of the dangle will have to stay at 97.63 degrees...

Just an update - it was my meter. Replaced it and am now in the process of trying to figure out and map/diagram the wiring in this old place. I'm sure I'll have more questions later.

Thanks, Patrick

Hi Patrick,
Good luck, look forward to hearing from you.

You can convert the old AC recpticles to 120 volt outlets by a couple of short #12 wires wirenutted to any larger wires(#10?), you will need to identify each end and mark with white tape and place on the neutral bar.
Knew the meter was bad as you didn't mention everything burning out. Plus I don't know when the last time I saw 590 volt wiring.
If an analog meter, a resistor used as a shunt may have burned out.
Also place on a Single Pole 20 Amp Breaker.