I have power in a receptacle but nothing works when plugged in.?

Question

Tried to turn on my wall A/C but it would not work. I thought it was dead (old unit), so I brought in another (almost new). It doesn't work either. I thought it might be the receptacle so I threw the breaker and started to remove that. I saw some sparks and the breaker went off when I accidentally touched metal-to-metal (turns out I had thrown the wrong breaker) so I know there's power in the box . Next I threw the right breaker, switched out the receptacle and it still does not work. No changes have been made to my wiring since I last ran the A/C last summer. The only electrical "event" was when Con Ed was working in the street a few months ago and my house's power went off. Half came back on and I realized that they had left so they had to come back. I recall them saying they had to "bridge" something. They fixed the problem and all my power was on but I didn't test the A/C at the time. But now two of the A/Cs on 20 amp circuits (240v) are dead. Should I call Con Ed or an electrician

Answer 1

Your house is (most likely) wired from the power company with single phase 240 volts. That means you have two wires that independently carry 120 volts when measured to ground, but 240 volts when measured voltage from one of the 120 volt lines (call it line "A") to the other 120 volt line (call it line "B"), plus a neutral wire (usually bare as it comes to the house, but white inside the house) that measures "nothing" when measured to ground. All 240-volt circuits are a combination of two 120-volt circuits (but keep in mind, the two 120 volt sources are different, one line "A" and the other one line "B").

The breaker panel is designed so that half of the breakers can access line "A" and the other half can access line "B". It takes one circuit from line "A" and one circuit from line "B" to make a 240-volt circuit. Most 240-volt breakers are made together, so you may only have one handle to switch it on and off, but you are actually always switching two breakers at the same time. If one is not working properly, either because it will not reset, or because it is worn out and will no longer conduct electricity, then you will be 120 volts short of what you need at the receptacle for a full 240 volts.

Therefore, the two 120 volt wires (one "A" and one "B") going to any 240-volt circuit, each has to have its own breaker, even if they are together.

Get a simple voltage tester that will measure at least 240 volts AC (alternating current, which is what you have in the house, as opposed to DC, direct current, like in a flashlight, or anything else with batteries, or a car.) Unplug the A/C, them measure the current between the two color wires at the receptacle (usually both black, or a black and a red), you should read 240 volts.

If you read nothing between the two color wires, be careful, one of the wires may still be "hot" with 120 volts AC. So, you should also measure each color wire separately, by placing one probe from the tester on the color wire, and the other probe on a ground (green or bare), or the neutral (white). If only one of the color wires is "hot" then you are not getting the 240 volts to the receptacle, and the A/C will not operate.

If you are getting a full 240 AC volts at the receptacle, while it is rare, make sure the receptacle is good by testing through the slits in the receptacle that the plug actually goes in when you plug in the A/C (you should do this before checking the wires at the receptacle, since it is the final point of the circuit, then work backwards toward the breaker panel, to save you time and trouble).

Lastly, if you have not yet discovered the trouble, check for a full 240 volts of power at the breaker. Using the test probe on the breaker, while it is in the "ON" position, place the test probes on the bare portion of the wires as they leaves the breakers at the same time. From breaker-to-breaker you should read 240 volts. If you do not, you may have a bad breaker. To check for this, test each color wire as it comes from the breaker in the "ON" position. Do this by placing one probe on the breaker wire, and the other probe on the ground bus (where all the bare wires are connected) or neutral bus (where all the white wires are connected. If both breakers are good, you should read 120 volts at each wire from each breaker.

If you do not read 240 volts between the two breakers, but you read 120 volts from each breaker to ground, the breaker may be installed into the panel in such a way, as both are accessing power on the same line, "A" or "B". Move it (or one of them, if they are not tied together as a unit) so that one breaker is accessing its power from line "A" and the other from line "B". That will guarantee that you have 240 volts ("A" + "B" = 240 volts AC)

Despite what you might hear, both 120 volts and 240 volts is plenty to cause death.

Answer 2

240V is actually 120V x 2, since you have some power to the outlet but nothing works, I would suspect that one side of it is not working. If you have a meter, check across the two poles of the outlet. You should have 215-240V. If you check each pole to the ground, you should have 108-120V.

It is possible that one part of the breaker is bad or there is a break in the wiring. Replacing the outlet should rule that out as the culprit. An electrician should be able to fix this in either case.

If you do check with a meter and you have 110V from each pole to ground, but nothing across the poles, then it is possible that there is a problem with the service coming into your breaker box, in which case Con Ed will need to address.

Answer 3

Sounds like you have a 220v air conditioner. If so you need 120 on both sides of the plug. You should have that plug tested to make sure.

When the electric company was working it may have messed you up. Call them and have them make it good. (Why not, It's free)

If you are doing this yourself be careful! From the sound of your question you already have had sparks flying. :)

Note: 220v is enough to cause death.

Answer 4

I would call Con Ed. Did you try to plug in something else to see if it would work? Also check to see if that outlet is on a three way switch. Sometimes it's as simple as flipping on a switch that you thought had no use. :)

Answer 5

con ed con you call a electrican