Another low voltage hot neutral question

NorthGuy

Joined Jun 28, 2014
611
Hmmm ... with a load the neutral to ground voltage is around 120V ... without a load the meter is reading 15V.
You need to try to draw some sort of schematics.

Assuming your load is functioning, there must be 120V between the other end of the load and the wire which you call "neutral" (otherwise the load wouldn't function). You say this is 120V between "neutral" and ground. This leaves us two possibilities:

1. There's 120+120V=240V on the other side of the load (relative to the ground). If there's a place which is 240V from ground, your house is totally miswired and one of the hot legs is connected to the ground. Easy to check. Measure between each of the legs and ground. If you get 240V/0V, your ground is wrong.

2. There's 120-120=0V on the other side of the load (relative to the ground). If that's true, the load is connected between ground and what you call "neutral", which actually means that it's not really neutral, but some hot wire of white color. When it gets energized, you get 120V. When not, some sort of device, such as dimmer or fancy 3-way switch pulls this wire to the ground. Easy to check too - look for dimmers and three way switches and measure conductivity between them and your "neutral".
 
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MaxHeadRoom

Joined Jul 18, 2013
28,617
What do you use over there?
It has been 40yrs since I left the electrical field in the UK, at that time the 'Screwnut' connectors were not allowed, IIRC they had to be screw terminal of some kind. Exactly what the regulation was I am not absolutely sure.
Max.
 

inwo

Joined Nov 7, 2013
2,419
Hmmm ... with a load the neutral to ground voltage is around 118V ... without a load the meter is reading 15V. Are you sure you are testing line side of switch?This is on every switch ... however, one switch the load voltage is around 110V ... a little lower than the others. Then that must be the last one in the circuit.
What type of load?
What type of meter?
 

inwo

Joined Nov 7, 2013
2,419
:eek:
As others have confirmed, definitely points to a VERY high resistance in the neutral somewhere, a check from neutral to earth at different points, should pin point it, there should be almost no difference at any point, just a small difference allowing for current in the neutral if a load is present..
Max.
+1

You don't seem to be getting anywhere checking under load.
Kill the power and try the Max way!
 

inwo

Joined Nov 7, 2013
2,419
It has been 40yrs since I left the electrical field in the UK, at that time the 'Screwnut' connectors were not allowed, IIRC they had to be screw terminal of some kind. Exactly what the regulation was I am not absolutely sure.
Max.
They make a similar, looking wire nut, with a set screw.

Screws and terminals are subject to being mis-installed.
The scotch-lock tm. that I used for years are a pain to remove but are fool proof. (if wires are even) Twist until it slips.
 

Thread Starter

drchance2014

Joined Jul 31, 2014
24
I'll post this and then head back to kill the circuit and test continuity between ground and neutral ... at least I think that's the "Max way". FYI ... using Fluke 87 III digital meter.

So here's a picture of the circuit ... sorry ... I tried to do something quick and may have put too much info on the drawing. Nonetheless it shows the three different light sets on this one circuit. One switch for LV, one switch for light over stove and three switches for the kitchen lights. The blue line shows the two switches that were in the previous posted photo ... they are located next to each other in a brick wall.

I tested all five switches ... neutral to hot ... load and no load ... and got these results
Living Room load 2V no load 106V
Stove load 19V no load 106V
Kitchen1 load 54V no load 106V
Kitchen2 load 54V no load 106V
Kitchen3 load 4V no load 106V

That last kitchen load looks interesting ... but they're all over the place!
 

Thread Starter

drchance2014

Joined Jul 31, 2014
24
I Took my Fluke ... dialed it to continuity (ohm) mode ... put a probe on neutral and a probe on the twisted bare ground wires and there was no reading ... it's wide open. I did this to each light switch box with the same results.
 

inwo

Joined Nov 7, 2013
2,419
Then problem is between box and main panel.

Check main panel. I noticed main panel has isolated neutral.
See if zero ohms between grd and neutral. (check for voltage first, should be zero)
That's what we call a "feeder" panel as apposed to "service" panel, which has grd and neutral bonded.

Fluke 87, my fav.:D
 

Thread Starter

drchance2014

Joined Jul 31, 2014
24
Yes ... my uncle gave me the Fluke about a year ago. I tossed my no-name digital to the side that I got with my electronics training back in the mid-80's. I went the computer route as far as a career goes. I just never spent the time trying to better understand AC ... I'm okay with DC ... but AC confuses the heck out of me ... especially when we would start talking about three-phase motors ... ack!
BTW ... I went back to do the continuity check again and I think something like 3.9M is way to high as well (almost open?). I kind of like analog meters when doing continuity checks.

 

MaxHeadRoom

Joined Jul 18, 2013
28,617
The symptoms are high resistance neutral, the ideal meters for this problem are both high voltage and resistance meggers, of course which you don't have.
But the Fluke should be able to diagnose the problem, the one down side I have found with Fluke, is before it shows a low battery, you start getting weird readings, I had a maintenance electrician that was stumped over a 240vac reading on a 120v circuit.
I got him to change the battery and Voilà .
Max.
 

inwo

Joined Nov 7, 2013
2,419
Will you sell it to me?:D

When using for low ohms check, press range button until it reads ohms.
It will be much more stable.
I hate auto range. I select range for everything.

Checking ac volts it will often read something like 110. Oops it's mv.:rolleyes:

I don't trust your funky ground connections.
Check between neutral bar and ground bar in panel.
First ac volts then ohms. (although nothing can hurt a fluke 87):D
 

Thread Starter

drchance2014

Joined Jul 31, 2014
24
Yes! I agree ... there's little indication the battery is dead until you start seeing weird things. I put a fresh 9 volt before starting this little journey a couple of days ago. I will also on occasion test continuity between the probes themselves and test for 120 from a know good outlet.

I just tested a known good light switch for continuity between ground and neutral and it reads much better 1ohm ... sends me an audible beep indicating they're connected. Okay ... now I know what it should look like when it's working.

I think it's just incredibly weird how the lights will start working out of the blue (like this morning) and then just stop (around 1pm). It's like I've got a squirrel in the attic that is toying me. I'd like to see the lights start working again so that I could kill the circuit and test for continuity again ... I'm sure it would be okay.

I just need a minute to think about how there could be a disconnect ... but only sometimes. This neutral wire goes through a total of thirteen recessed lights ... I'm guessing a loose connection at any one of them could be the culprit.
 

inwo

Joined Nov 7, 2013
2,419
"This neutral wire goes through a total etc."

You didn't mention that.:eek:

I thought you were testing at the first device where neutral comes from panel..

Recessed lights are most dificult to check.
Some of the lights should work unless the fault is in the first.
 
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Thread Starter

drchance2014

Joined Jul 31, 2014
24
Hmmm .... well I am testing at the first switch ... where the power comes in. So I think you are correct that it is somewhere between the breaker box and the first switch.

Yes, that neutral goes through a few lights. Sorry if I wasn't clear on that earlier ... I was hoping the drawing would eliminate some confusion. But since the continuity test fails at the first switch (that photo with both the Living Room and Kitchen switch) I thought I could eliminate the break in the neutral being somewhere in the recessed lighting.

I did spend Tuesday in the attic crawling from one end to the other checking the wires from entry into the attic until it goes down the wall to the switch. The wire looks in good shape although there were some areas I could not get to easily. I did find a dead squirrel ... a little unnerving but I guess I should expect to find critters every now and then.

If this neutral and ground entering the house should have 0 resistance ... then this should be easier to find than going through a bunch of lighting fixtures. It's open at the first switch. Am I thinking about this correctly?
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
It's like I've got a squirrel in the attic that is toying me.
Ah yes, the Old squirrel in the attic trick!:p

The thing with a high resistance connection, when you switch off the power the connection 'relaxes' (cools off) the resistance of the poor connection causes heat to some degree, however small when you re-power the circuit. When you switch the load off, you measure full voltage as there is no drop across the bad connection.
Personally I would turn on the affected loads and progressively measure between neutral and ground, until I found the voltage difference.
Max.
 

inwo

Joined Nov 7, 2013
2,419
I'm not clear on the layout.

There are two ways to wire.

One is running power wire from panel to switch.
The other runs power to the lights first.

The main thing we need to know is, the first connection after the breaker panel.
Is that in the switch?

If you have high resistance grd-neutral there, then there is no need to look further down the circuit.
This should be the exact same wire that you ohmed in the panel. Just the other end.
 

Thread Starter

drchance2014

Joined Jul 31, 2014
24
I can try to measure the voltage like you said ... after turning the circuit back on ... I think I got that right. Although there is no place to test in between the breaker box and this first switch. I consistently get 122V at the breaker box and 105V at the first switch. Looks like I need to spend more time in the attic looking at the run coming into the house. Unfortunately there's no way to test that wire at different points without of course cutting into it.

 
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