Bought a house in May that came with a window air conditioner connected to a 220V outlet. The air conditioner is gone with no plan to replace so I want to remove the outlet. I went to the breaker, flipped the double pole 20A breaker to "Off" and then use my power line tester to make sure the wire was not live and to my surprise, the line is still live. I confirmed I am turning off the correct breaker. What am I missing?

  • 1
    How do you know that it's the "correct breaker" if it doesn't turn off that circuit? Are there other double-pole breakers in the service panel? – Niall C. Dec 4 '11 at 3:47
  • I assume it's the correct breaker because I traced the wire running from the outlet to the service panel to the breaker. – rodey Dec 4 '11 at 3:56
  • What type of tester did you use? Non-contact testers can pick up voltage from nearby lines – Steven Dec 4 '11 at 17:47

I'm not clear how you traced the wire, unless it's exposed the whole way?

If you do have access to the wire, even if it's just when it enters the panel, you should use a non-contact voltage detector to check for power. When you flip the breaker, it should go off.

There's a possibility that there are two feeds to the outlet. I would start by going through all breakers one-by-one (or several at a time, to narrow it down) to see if the power shuts off.

Keep in mind that you can get 220 by bridging two 120V breakers, and so one single breaker may not turn off all power. This setup is not legal, but it sounds like it may not be wired correctly anyway - don't make any assumptions when it comes to bad wiring!

Worst case, shut off all breakers, and confirm the power goes out. Then start turning things back on (an assistant and/or non-contact detector that beeps will help you here).

I personally would not touch any of those wires while my meter still read voltage, and I recommend no one else does either.

  • 1
    I would physically remove the breaker from the panel, or at least pull it from the hot buss. To do this you need to remove the cover, most breakers will tilt out from the center. Now you can do two things, test for voltage and if you get a 0 reading you can confirm wiring pair with an ohm meter. As gregmac said, if you are showing voltage, be extremely careful, don't assume anything. Get a second contact type meter and check from hot to neutral/ground before you handle the wires. – shirlock homes Dec 4 '11 at 13:21
  • My tester isn't anything fancy, something I picked up from Lowes where you just touch it to a line and it beeps if the line is hot. I know for sure the line was wired to a single breaker (20A double pole). I disconnected both wires from the breaker, the ground and the common and pulled the wire entirely out of the service panel. At this point I knew the wire was not hot and proceeded to remove the outlet. Thanks for a great answer! – rodey Dec 4 '11 at 17:09

I had a problem like that, I tested my NEMA 10/30R 125/250V dryer outlet with the breaker off and still got a reading of 220V. I called the electrician that wired the house, and he read 0 volts with his tester and then read 220V with mine. My tester was a Sperry multi-meter and his was a Knopp.

Sperry Multi-meter

The Sperry Multi-Meter

Knopp K60 Voltage Tester

The K60 Knopp tester

Because the Knopp tester is solenoid driven you cannot get any back-feed from anything on the panel. The multi-meter can pick-up voltage back-feed and show up as voltage on your tester. This can also be a problem with proximity testers.

The older style testers like this is made by a lot of manufacturers.

Also the Knopp is considered a hi-impedance tester and the multi-meter that I had is a low-impedance tester.

I'm not saying that it's OK to presume the tester is at fault and I don't know what tester that you used. You should always check and double check and if in doubt, do like you are doing and ask questions. If you are still not satisfied, call an electrician.

Also, what reading do you get from one side when measured to ground compared to the other side to ground?

  • 4
    Voltage back-feed is still voltage. There are still 220V on that line, if that's what your meter is showing you. The difference is that it's a very small current, and not enough to turn on the Knopp tester you showed. This also MAY mean that it won't injure you (current is what kills you, not voltage), but unless you're willing to risk your life to do a little electrical work, I'd recommend finding out what you need to shut off to get your meter to read 0 before touching anything potentially live. Use a non-contact testor, and check every time before you touch anything that may be electrified. – gregmac Dec 4 '11 at 6:32
  • Unfortunately for me, my power company won't turn the transformer off to the block. Anytime questionable I would turn the main breaker off, and then check before doing anything. Actually that time I did call an electrician. – lqlarry Dec 4 '11 at 7:33
  • You got high and low impedance backwards. Your multimeter is high impedance. The electrians tester is low impedance. – Peter Green Jan 18 '17 at 15:45

Best advice is to "pull" the breaker from the bus bar. In my experience, a breaker can become locked due to the contacts being welded internally and WILL NOT disconnect power/voltage from the circuit.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.