Looks like reverse polarity but isn't

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jcarter

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History: house is 10 yrs old. In master bedroom have used all sockets at one time or another with no problems. PROBLEM: we recently switched from cable to satilite. When the tech was putting in the receiver in our bedroom he plugged it in the socket behind the TV. Now let me explain this socket has been used for the last 9 yrs we have lived here. We have 2 surge protectors hooked up and on those we have a TV, Stero, DVD, CD player, 2 phone chargers and 1 record player. have never had a problem. But this guy plugs in the reciever and pop there goes the reciever. He tested the socket and it gives a bad reading. My husband the electrician brings home is fluke meter and find that out of 5 outlets only 2 give a good reading. He has removed all 5 just to double check and everything is wired correctly. We the outlets that have wires in the back so I found a site that said that could be the problem so we took them out of the back and wired them to the scews, that didn't work. He noticed that when he killed the power that everything went out lights and all so he has checked the switches as well. Everything is wired correctly. He has tried to trace the wiring back to the panel and everything is wired correctly there as well. He thought there may have been a junction box in our attic but it appears everything is straight wired to the panel. He is at his wits end. We don't understand how everything was working just fine but this one piece of equipment blows when plugged in the wall directly. HELP ANY IDEAS OF WHAT ELSE WE CAN DO OR LOOK FOR. He had a thought that since he is getting reading that appears to be rev. polarity but wires are wired up correctly that maybe he created a reverse polarity that this would work. but Not sure. While he has been a electrician for only 5 years he is still learning and this is really bugging him. :confused:
 
Re: Looks like reverse polarity but isn't

jcarter, the first thing to do when trouble-shooting a problem is to isolate said problem and not trouble-shoot the whole house. If two receptacles are good then disconnect the wiring leaving the second receptacle. Make sure the wiring is disconnected also from the third receptacle if this can be determined and see if there is a short between hot and neutral or hot and ground ( on the wiring between second and third receptacle ). It probably want be a dead short just a low resistance reading. Once the problem is isolated then you have to figure out how the wiring runs from point A ( second receptacle) to point B ( third receptacle) this is assuming that the resistance reading is bad.

[ February 26, 2006, 10:49 AM: Message edited by: growler ]
 
Re: Looks like reverse polarity but isn't

When you say a BAD reading what was it ? Was the circuit checked from hot to ground or hot to neutral?Was continuity checked from neutral to ground?What type of wiring is it NM,BX,Pipe?
There is a limited amount of problems that can occur sometimes it takes patience and a step by step approach to solve a problem.Troublshooting is a process of elimination and certain procedures will stop alot of necessary steps.
 
Re: Looks like reverse polarity but isn't

Bad reading is : hot to nuetral is 118 volts and hot to ground is Zero.
 
Re: Looks like reverse polarity but isn't

Jcarter, 12/3 says that you have a multi-wire branch circuit or some of the outlets are switched. What do you get when measuring from black to red?
 
Re: Looks like reverse polarity but isn't

Ok so there is an open ground somewhere when you say 12/3 is that 12/3 with ground or 12/2 with ground ?But that should have no affect on a satellite reciever all that I have seen come with a 2 prong attachment cord caps.
To me the easiest way to isolate a open/shorted wire situation is to go to the middle of the circuit break all connections and see where that trouble is.It will be either ahead of you or behind and break it down that way till the trouble is found.
 
Re: Looks like reverse polarity but isn't

my husband says we have 12/2 with ground. We have black and white with green for ground. He said will try to break the circuits down and go from there. If we have a reverse polarity with the wires connected correctly what would happen if we crossed the wires and but the black on Silver and the white on brass. This was something he had thought about trying but was not sure what would happen.

Thank you for your advise. He has spent 2 nights and 1 day looking at these outlets and trying everything he could.
 
Re: Looks like reverse polarity but isn't

Tell him dont.That is dangerious.Actually this sounds like its over his ability and he needs help from an electrician
 
Re: Looks like reverse polarity but isn't

First of all never try to rig a fix. Keep the white on silver and the black on the brass or gold side. Are you sure you even have reversed polarity. If you are using one of those plug in testers, check again and make sure that you were not reading an open ground. Reversed polarity will not cause a piece of equipment to blow up but it is a safety concern. Start looking for where you lost that ground, you may find more than an open ground wire.
 
Re: Looks like reverse polarity but isn't

no he does not have a fear the computer but he is not a good typer so I type while he relays to me what to type.

He says HI!!! and thank you for your help. Will try to put some of the advise we got to work after lunch.

Oh, what he is doing is not over his head it is simply that he has never run across this problem in the School system he works for. And so if you've never done it then you have to learn.

Thanks again. Signing off for now.
 
Re: Looks like reverse polarity but isn't

first of all it sounds like you could possibly have two different problems, the receiver not working but everything else working fine suspects the receiver is bad, have you tried plugging it in a different room to verify that the receiver is good?, secondly Im guessing in the process , you have discovered a previously not known problem that has been since the house was built. from your description the only problem you have described is an open ground on various recepts..not to be rude and dont take this wrong but do take it, if your husband even so much as sujested reversing hot/neutral it tells me he IS definatly over is head, I know hundreds of (electrical installers) that are very well at what they do, however it does not make them an electrician. A simple tone generator will help isolate this problem, any capable electrician could diagnose this problem easily in 15-20min..good luck
 
Re: Looks like reverse polarity but isn't

Originally posted by jcarter:
Bad reading is : hot to nuetral is 118 volts and hot to ground is Zero.
Click to expand...
This is the indication of either open ground or reversed polarity. What is read between neutral and ground? If there is voltage, that's reversed polarity.

As Growler touched upon, when there is a problem that affects part of a circuit, it is as likely to be in the last correct box as it is in the first affected one, so check those two also.

Here's what may be the best suggestion you'll receive: Plug a 3-wire extension into a known-properly-wired receptacle, on another circuit, and carry the female end around with you.

The cord becomes your 'reference'. Now, you can measure for voltage between each cord receptacle slot and each wall receptacle slot. You could read 0 or 240 between the two hots, depending on phase.
 
Re: Looks like reverse polarity but isn't

Originally posted by growler:
First of all never try to rig a fix. Keep the white on silver and the black on the brass or gold side. Are you sure you even have reversed polarity. If you are using one of those plug in testers, check again and make sure that you were not reading an open ground. Reversed polarity will not cause a piece of equipment to blow up but it is a safety concern. Start looking for where you lost that ground, you may find more than an open ground wire.
Click to expand...
It can blow up some electronics.Look at the schematic and you will see why.Some have voltage supressers built in.
 
Re: Looks like reverse polarity but isn't

Originally posted by LarryFine:
What is read between neutral and ground? If there is voltage, that's reversed polarity.
Click to expand...
I watched the "boss" (back in the early 70's) switch the white wire and black wire in the panel because the black had a short and the white did not (more than once, it was a year before I realized this was not an accepted practice).
 
Re: Looks like reverse polarity but isn't

I guess for my 2 c worth their seems to be only 2 reasons I can think of for the reading you get, open ground which would not cause the electronics to blow or reversed polariy which again is dangerous but should not cause any problem with attached equipment. The suggestion to look at adjacent walls is a good one because any reversal of course carries on to the next outlets in line regardless of how they individually are connected. I normally start by shutting the circuit off and determine what all is hooked up all out lets and lites. I then find the feed to make sure that is connected correctly. Oftentimes the feeds start at a switch box and continues from there but not always. Hope this mite help some. also are you absolutley certain that this circuit is being fed from the panel with 12/2 by checking at the panel for sure? If you have a circuit that is actually sharing a neutral IE red blk wht going out then a loose neutral is a definate possibility. In a normal situation at 240 volt bus voltage I would expect to see 120 volts at the plug and not 113 under no load conditions. Thats what hints at loose neutral in a multiwire circuit.

[ February 26, 2006, 04:40 PM: Message edited by: stew ]
 
Re: Looks like reverse polarity but isn't

Sounds to me like the satellite equipment tied the neutral and ground together in the equipment and you have the ungrounded phase on the neutral side of the receptacle.
 
Re: Looks like reverse polarity but isn't

Originally posted by growler:
Jimwalker, I'm confused, which way does current flow in an AC circuit?
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Both ways but thats not what causes the problem.Often they install spike protection and if it sees voltage between neutral and ground then it might burn up.In this case it likely seen 120
 
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