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Replaced switch and receptacle, now getting hot/ground reverse on tester

Replaced switch and receptacle, now getting hot/ground reverse on tester

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  #1  
Old 07-28-13, 01:37 PM
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Replaced switch and receptacle, now getting hot/ground reverse on tester

Hi,

I am working on a box that previously had two switches, one receptacle (single), and an indicator for one of the switches. The two switches control two different lights, and are on separate circuits.

I successfully replaced one switch with a single pole switch and that works fine, as does the rest of the circuit.

The remaining switch and receptacle are for an outdoor light. The conduit in the back has a single cable with a red, black, and white wire. I connected the red and black wire to the red and black terminals on the switch/receptacle combo, and the white to the white terminal as instructed by the packaging.

When I flip the circuit back on and plug an outlet tester into the receptacle, I get a hot/grd reversed pattern on the lights and none of the outlets or lights on the circuit are functional.

Any suggestions on what might be wrong? I can send pictures if that would be helpful!
 
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  #2  
Old 07-28-13, 01:52 PM
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Welcome to the forums.

That wires in the conduit....red, black, white.....are those coming from the switch ?

If they are then red probably goes to the switch but you need a hot and neutral to the switch. That would mean you would need a neutral and hot splice at the switch location.

Does that make sense ?
 
  #3  
Old 07-28-13, 02:58 PM
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Hi PJmax,

Thanks for the speedy reply! I just drew up a quick sketch of the box and switches as they stand now. It's attached (I think).

I'm not sure how to tell if the wires are coming from the switch. They are coming from the wall, into the box, and I think they are live. I've got a no-contact tester (Klein Tools Non-Contact Voltage Tester-NCVT-1SEN at The Home Depot) that lights up near the red and black wires, but I'm not sure how to be certain that it isn't just one of the wires that's live.

I'm not clear what you mean by hot and neutral splice - but shouldn't my white and black wires be providing the hot and neutral?
 
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  #4  
Old 07-28-13, 03:42 PM
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Try: Black to A, Red to B, white to CD. The hot may be internal from A to receptacle.

Mod note: Suggestions above could create a dead short. Do not try. B is neutral a red wire never should go to a neutral. CD is the hot (ungrounded conductor). Unless remarked a white wire should never go to a hot.
 

Last edited by ray2047; 07-28-13 at 04:30 PM.
  #5  
Old 07-28-13, 04:21 PM
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I've got a no-contact tester
But not useful for any real testing. It can often show false positives due to induced voltages. A cheap $8-$10 analog multimeter is what you need for any real testing. Digital multimeters are tempting but cheap ones often have to high an impedance to cancel out induced voltages. Receptacle testers can give false readings for reasons such as open ground. When they show a bad reading the next test is to check with a multimeter.
  • Wide slot to ground. Should be ~0v
  • Narrow slot to ground. Should be ~120v.
  • Narrow slot to wide slot. Should be ~120v.
 
  #6  
Old 07-28-13, 05:37 PM
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shouldn't my white and black wires be providing the hot and neutral?
You'd think so, but someone may have fed the power in on the red wire and connected the light to the black wire. You can't really tell that without a multimeter.

What you can do, though, is swap the red and black wires. IOW, black to A, white to B and red to CD. So long as you leave the white on the neutral terminal you should be OK.
 
  #7  
Old 07-29-13, 06:36 AM
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Hi all,

Thanks for the advice! I've now tried black to A, white to B, and red to CD, with no luck. Additionally, I no longer get any signal from the outlet tester, though I know the wires are still hot.

In addition to the no-contact tester, I've got a contact tester that reports 110/220 (Commercial Electric 110/220 VAC Voltage Tester-MS8900H at The Home Depot). It's reading 110 when I connect one end to any of the three wires (white, red, or black), and the other to the box. That seems particularly troubling.

I also tried the suggestion of white to CD before the moderator was able to post the warning. That, as predicted, likely created a quick dead short, which flipped the 20amp breaker on this circuit. Is it possible that this damaged other outlets or lights in the circuit?

Thanks for all the help.
 
  #8  
Old 07-29-13, 06:46 AM
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A dead short typically does not last long enough to do any damage.
 
  #9  
Old 07-29-13, 06:55 AM
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The tester you need for troubleshooting an electrical system is as analog multimeter. That will tell you how much potential is on any given conductor while filtering out induced voltage.

An analog multimeter will also let you perform other important tests such as continuity. I linked to one at HD, since that is where you got the tester you used. I suspect it was reading induced voltage on two of the conductors. I hope so. If not, the wiring has been damaged or connected inappropriately somewhere.

How is the light wired?
 
  #10  
Old 07-29-13, 06:59 AM
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Brief update - I am still getting the hot/grd reverse from the outlet, so long as the receptacle is screwed in. If it is loose, I get no signal.
 
  #11  
Old 07-29-13, 07:37 AM
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Can you post a pic of both sides of the switch?
 
  #12  
Old 07-29-13, 11:05 AM
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Standard combo single gang switch/receptacle

Remove combination switch and receptacle. Make a continuity test between wide slot of receptacle and the silver plated screw terminal using a ohmmeter or continuity tester. This is your neutral (white). The two terminals that are common is the hot black, and the opposite single terminal is your load red.
 
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Old 07-29-13, 11:23 AM
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I've got a contact tester that reports 110/220 (Commercial Electric 110/220 VAC Voltage Tester-MS8900H at The Home Depot
Just makes you shake your head. The tester is clearly marked 110/220 yet it is intended for use in the USA where we have 120/240.

On topic that does appear to be a test light and therefore your reading accurate except it is really 120 not 110.
It's reading 110 when I connect one end to any of the three wires (white, red, or black), and the other to the box. That seems particularly troubling.
White to ground should be 0. What is the wiring at the outside light (or wherever the 3-conductor cable goes.). I'm suspecting a switch loop at this point.
 
  #14  
Old 07-29-13, 11:32 AM
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Here are photos of the switch/receptacle combo from the front and sides.

A & B sites are on the left, C/D on the right. Red is currently at A, white at B, and black at C/D.
 
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  #15  
Old 07-29-13, 11:48 AM
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All looks as expected. Now we need to see the wiring at the other end of the 3-conductor cable. I'm thinking switch loop as I wrote earlier.
 
  #16  
Old 07-29-13, 12:04 PM
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So to check that, I should just pull the fixtures controlled by the switch down to reveal the wiring?

There are two lights. If the above is correct, I'll get photos of both loaded shortly.
 
  #17  
Old 07-29-13, 12:36 PM
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Where is the neutral for the receptacle?
 
  #18  
Old 07-29-13, 12:49 PM
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It appears from your picture that the two terminals on the right side of your switch/receptacle combo, with the two black screws and the tab between them, are the two connected terminals where power should be fed in. The load for the light would go on the brass terminal closer to the switch and the neutral for the receptacle would go to the other brass terminal, closer to the receptacle.
 
  #19  
Old 07-29-13, 02:10 PM
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There are two lights in the series controlled by this single switch. I pulled the first of the two off the exterior of the house, and it had only two wires - 1 white and 1 black. I cleaned out the box, and replaced the light.

For the second light, it's an old flood light, which I pulled off the house. There's a cable running into the base of the flood light, and I can't see what the wires are inside without cutting into the cable, or removing the light from the house. Since I'm not sure I can get it all back together if I take it apart, I've left it alone for now, but I took a quick picture (attached) - though I'm guessing that's not particularly helpful.

I've also tracked down the previous switches/outlets. I wasn't involved in removing this from the wall, so I can't be sure of how it's wired, but I'll give it my best guess (see diagram and photos).
 
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  #20  
Old 07-29-13, 03:17 PM
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Use an analog multimeter to determine which of the three wires in the cable for your switch/receptacle combo is the hot wire, and connect it as suggested in post # 18.
 
  #21  
Old 07-29-13, 03:35 PM
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Bill, he said all three were hot to ground using a test light.

C. Ford, is there no box for the light? There certainly should be. From that it seems there is an undiscovered box the 3-conductor cable goes to or am I missing something.
 
  #22  
Old 07-29-13, 04:02 PM
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I'm not seeing a box in there either - add that to the list of problems. I've got an electrician coming out to check all this stuff out tomorrow, as clearly I am in over my head. I really appreciate all the advice, and I will report back once I learn what's going on. Stay tuned!
 
  #23  
Old 07-29-13, 04:38 PM
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The picture on the left kinda looks like an old Stonco(?) surface mount box for a flood head. I think that's a cable connector at the back of it. If it is, there might be a couple of screws buried under the paint on the front side that will get you into it.
 
  #24  
Old 07-29-13, 04:56 PM
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Bill, he said all three were hot to ground using a test light.
Yep, and that either makes no sense or is pointing to conductors that are in contact when they shouldn't be. That's why I advised him to get an actual meter.
 
  #25  
Old 07-30-13, 08:48 AM
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I thought that digital multimeters like "Fluke" draws.less power than analog for the voltage readings thus it doesn't effect the accuracy of the reading. It is using the voltage of the circuit you are reading, not the battery voltage used for ohms, etc .
 
  #26  
Old 07-30-13, 09:18 AM
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You need a low enough impedance (high enough load) to drain off spurious induced voltages. A Fluke probably will give a accurate reading but it is not a cheap digital which is what we are talking about when we refer to digitals. So do you want to spend $10 for a cheap analog that gives accurate readings or $50+ for an expensive digital meter that gives accurate readings? Actually in the hands of someone who understands its limitation a cheap digital is okay but then you need to know how to interpret the readings and when to ignore them. For our purpose here working with newbies that complicates helping them.
 
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