power at switch and outlet, but lights won't work

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  #1  
Old 11-02-04, 05:33 AM
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Question power at switch and outlet, but lights won't work

Okay, I hope someone can offer me some guidance here. I have a circuit that some of the outlets work on, none of the switches work and a couple of the outlets don't work. But, when I use a voltohmeter to test for voltage, I'm getting 120 +-volts. I have voltage but the switch/outlet will not work. Any suggestions?
 
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  #2  
Old 11-02-04, 05:54 AM
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None of us can do much until you supply more information.

Did this circuit used to work?

Did you do anything to modify it?

How are you testing for voltage? What type of voltmeter do you have? Where are you testing for voltage (what are you connecting the probes to)?
 
  #3  
Old 11-02-04, 06:19 AM
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Yes, the circuit used to work. I have replaced two outlets and two switches, but it worked after I did that, all of a sudden I plugged in a dehumidier and that's when they stopped working. But, like I said some of them work and some don't, old and new. For instance, the two new switches I replace in the kitchen don't work, but the new outlet I replace in the dining room does, and the other outlet in the dining room doesn't. Then from there it goes into a hall bath, and the light doesn't work, then it goes into a bedroom and the light doesn't work in there.

The voltohmeter I'm using tests for AC/DC voltage, ohms, and amps. I'm not sure of the exact name brand, I don't have it in front of me. When I test a switch, I'm using the red probe on the ground and the black probe on the black wire (or screw). I can turn off the breaker and retest the same way and it reads zero or +-.10 volts. On the outlets I'm inserting the red probe in the long slot and the black probe in the short slot.

I hope I've covered everything. Your help is greatly appreciated.
 
  #4  
Old 11-02-04, 07:17 AM
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If it used to work and stopped without any further changes on your part, then a connection probably came loose. So go back and double-check your connections. I sure hope you didn't use those backstab connections that just poke into holes. If you did, move the wire to the adjacent screw.

I'm not sure what you mean when you say the switches don't work. Does this mean that you can't turn the thing on, or that you can't turn it off?

Do you understand the purpose of the tabs on the sides of receptacles, and when you should break them off and when not? Did you look at the sides of your old receptacles to see where the tabs were removed and where not? Do you still have the old receptacles and switches to examine?
 
  #5  
Old 11-02-04, 07:21 AM
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Are you using a digital voltmeter? A digital voltmeter will give incorrect readings if a wire is disconnected.

I agree with John, check your connections again. IT does sound like one has come loose and is open.

Start with the r3eceoptacle where you plugged in the dehumidifier. If that one is fine then continue and check all the other receptacles and switches. Even chek those that work, looking for a loose connection on the downstream side.
 
  #6  
Old 11-02-04, 07:41 AM
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Thanks, I'll go back and double check. When I say that the switch doesn't work, I mean that when I flip the switch to the on position the light doesn't come on or when I plug a lamp into the outlet, the lamp doesn't turn on. But, when I test for power, it indicates that I have 120 volts of power at that point, even when I test the other end of the switch, when it's turned to off, I get 0 volts, then I flip the switch to on and I get 120 volts. But, the light will not come on.

This is a doublewide, so the receptacles are not a typical receptical. I have no idea what you are talking about with the tabs. Scary huh? lol. Anyway, I'll double check my connections, but I just don't understand how I can have power at that point and still the light doesn't work. I haven't tested power at the light though.
 
  #7  
Old 11-02-04, 07:55 AM
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Voltage but no power is very common. It usually indicates an open neutral (white wire).
 
  #8  
Old 11-02-04, 09:48 AM
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I had a similar problem a couple of weeks ago, albeit with a lights-only circuit. John Nelson pointed out the likelihood of an open neutral, and sure enough, a neutral had come loose in my triple-gang box. If a loose neutral is your problem, make sure your wire nut is large enough for the job and is very secure when you tuck it into the box.
 
  #9  
Old 11-02-04, 10:15 AM
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Digital voltmeters should not be used for ac circuits. They work fine if power is present, but if an open circuit exists they usually do not measure properly. You should only use an analog multimeter for measuring voltage on an ac circuit.

Measuring for voltage at a switch tell you very much, unless the switch has a neutral. If the switch is part of a switch loop then all you can test for is the hot wire being connected. You cannot test the neutral connection.

I am betting that you have an open neutral.

Two things to do.

Check each and every receotacle and switch you replaced. If you did not replace with a brand new switch or receptacle then do so now. Do not reuse receptacles or switches. If you wired using the "back stab" or "quick connect" terminals, then move those connections to the screw terminals. If you don;t find a problem at the receptacles you replaced, then check the other receptacles on the circuit.
 
  #10  
Old 11-04-04, 11:17 AM
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Okay, I checked the new outlets and switches, all seems to look good. I double checked the connections. Still no results. I even took the light down and inspected the wires. I even took the front plate of the dishwasher off and checked that connection. I'm getting power at these points, but nothing works. Whats going on? Any other suggestions that I could do before I call an electrician?
 
  #11  
Old 11-04-04, 11:23 AM
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Did you check everything on the circuit, even the receptacles that work?
 
  #12  
Old 11-04-04, 11:49 AM
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no, I didn't check the receptacles that are working. Only the ones that indicate they have power but doesn't turn on the light or lamp when plugged into it.
 
  #13  
Old 11-04-04, 11:52 AM
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You need to check every receptacle on the circuit.
 
  #14  
Old 11-04-04, 12:15 PM
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okay I'll check the ones that are working too. By the way, is there a more sure way to check the neutral than just making sure it's still connected to the terminal screw? Is there a meter, kinda like a voltage tester, that would help locate the problem?

So let me make sure I understand what you are saying. If a neutral wire have come loose somewhere, I can still get voltage at those points but a lamp or light will not work. So in other words, in order for an outlet/switch to work it has to have a neutral and power connections.
 
  #15  
Old 11-04-04, 12:21 PM
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You should be testing for voltage across the hot and neutral wire using an analog meter at each receptacle. You should not be using a digital meter.

You need to make certain that you have power entering a receptacle and power leaving a receptacle.

You need to test every receceptacle or switch location. Somewhere you will find that you don't have power. When you don;t have power, trace backwards from there and find where the problem is.
 
  #16  
Old 11-04-04, 12:34 PM
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okay, I bought one of the voltage testers that light up if there's power. So I've been using that instead of the digital voltohmeter. So somewhere I don't have power and how will I know which way trace if it ends up in the middle of the house? Shoud I go back toward the panel box?
 
  #17  
Old 11-04-04, 12:38 PM
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How are you testing for power using your tester? What two wires are you connecting your tester to?

You need to trace the wires back through the house. While there is no way to be absolutely sure about where the wires go without extsnsive testing, you can usually figure it out. Electricians tend to wire from the panel out. They go to the closest location first, then to the next closest location, etc.
 
  #18  
Old 11-04-04, 12:52 PM
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on the outlets I test by inserting into each slot, then once I remove the plate I test again on the screw terminals that are connected to the white and black wires. For the switches I have one on the ground and one on the black.
 
  #19  
Old 11-04-04, 01:00 PM
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Do the neutrals go through the switch junction boxes, or do the switch boxes contain only switch loops?

At the receptacles you should also test hot to ground.
 
  #20  
Old 11-04-04, 01:09 PM
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I'm not sure if I follow you. The kitchen light has power coming in at the actual light then to the switch. So I guess the loop is at that point. But somehow the outlets that are working on that circuit still continue to work when I had the wires on this light unconnected. And, this section is closer to the panel box. I wish I could insert a picture for you.
 
  #21  
Old 11-04-04, 01:59 PM
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The problem could be in the neutral wire. If it is the contact tester you are using won't show a problem.
The problem could be in any box on the circuit including light fixtures switches, receptacles and boxes with no devices.
 
  #22  
Old 11-04-04, 02:00 PM
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Your kitchen light switch is most likely a switch loop. How many wires go to the switch junction box? Does only the hot wire go to there? If so, then you have a switch loop. If the neutral wire goes there and then returns (highly unlikely) then you do not have a switch loop.

If you disconnect the wires at the light it should not shut off any other receptacles, unless you also undid the wire nutted connections that go further.
 

Last edited by racraft; 11-04-04 at 02:12 PM.
  #23  
Old 11-04-04, 02:49 PM
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I'll bet you can find the bad connection a whole lot faster by looking for it than by testing for it. Check every box on the circuit. Every single box. Every one. Yes, all of them.
 
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