I posted a while ago about getting a reversed polarity reading in two barns I have. The wired come in through the first barn, through a junction box, and to a 20 AMP switch that feeds the other barn, with some outlets and lights here and there. It is a mix #12 awg and #10 awg wiring, on a 30 amp breaker (yes I know I need to change it to a 20 amp breaker). The problem arises with the second barn. When I plug my polarity tester into an outlet in the first barn, it says polarity is fine, but when I turn on the switch to the other barn, polarity is completely reversed everywhere. Using a multimeter, I get around 117V going from neutral to hot and neutral to ground, with no voltage from hot to netural/ground, Unless I cut power to the second barn. I have opened all receptacles and junction boxes and can't find anything wrong with the wiring. Is it possible there is some sort of issue with the wires themselves in the romex? And ideas are appreciated, thanks.

Show us the switch and its wiring.

The switch controlling the second barn? It's just a basic 20 AMP switch I got at Lowes; the neutrals and grounds are pigtailed together, and I have the source wire on one screw and the wire going to the second barn on the other.

I get around 117V going from neutral to hot and neutral to ground, with no voltage from hot to netural/ground, Unless I cut power to the second barn.

Want to restate that


You said
"117V going from neutral to hot
"
And you said
" no voltage from hot to netural"

Exactly what type of switch are you using.

A disconnect switch or a simple snap switch.

Just to make sure I am on the same page as you, switches do not use a neutral conductor.

I meant hot to ground sorry.

A snap switch. 20 AMP. The neutrals are pigtailed together and not attached to the switch.

Kyle,

You are making us pull teeth here.

What is the source feed to the switch and how is the second barn fed?

Can you take pictures of the source connection to the switch and the connections from the switch to the connections at the 2nd. Barn, please?

The set up is just like a light switch. The source feed to the switch is 12/2 from a junction box in the first barn, and the outgoing wire from the switch is 12/2 going to the 2nd barn underground, the switch is in between. It's wired exactly like a light switch. Each black wire to each brass terminal, the 2 grounds in the box pigtailed together and a third grounding the switch itself, the 2 neutrals pigtailed together.

I can't post pictures because I'm not there today.

I don't think we are going to solve this just by logic. To answer your original question precisely, no a defect in the wire can not cause what you have described. You could have a break in the wiring but that would cause you to have no power to the second barn. You could have defective insulation but that would cause a short circuit and the breaker would trip.

Lets see if I correctly understand what you have said. You have power run to a sub panel in the first barn. In the first barn you have outlets and lights.
From the sub panel you have a 20 amp circuit run to the second barn. You have a 20 amp switch either in the first barn or the second barn to control that circuit.
You are using a meter to check for voltage between hot (black) and neutral (white) and between hot and ground. You are not using one of those little plug in devices that is suppose to tell you everything but ends up confusing you with false readings, especially about polarity. It is a misnomer to talk about polarity in an AC circuit. When people say polarity is reversed they really mean hot and neutral are reversed. Polarity in an AC circuit changes 60 times every second.

You have voltage between hot and neutral and between hot and ground in the first barn until you turn on the switch in the circuit to the second barn. Then you have voltage between neutral and ground but not between hot and ground in the first barn. Do you have power to the second barn when you turn the switch on?

You cannot have voltage between neutral and ground if you are properly grounded because the neutral and ground wires come together at the main panel. Check your grounding. Ground wires in a sub panel should connected to a ground buss which is connected to the ground wire going back to the main panel. Neutral wires should be connected to a separate neutral buss which is connected to the neutral wire going back to the main panel. The ground and neutral buses should not be connected together in the sub panel.

Please confirm my understanding and correct me if I have misunderstood.

You are nearly correct, there is actually no sub panel in the first barn, simply incoming 10/2 wire from the main panel back at the house entering a junction box. There is no incoming ground for some reason (I didn't do the original wiring), but there is a grounding rod that is connected to the wires in this first box, and everything is (supposedly) grounded. When I turn on the switch to the 2nd barn, the second barn works, but "polarity" (hot and neutral) are reversed everywhere. When I turn off the switch, it is back to normal.

Confirm that you are using a meter to do this testing.

Certainly this wiring without a ground does not met current code. It may however be grandfathered in. Take note that there is voltage on a neutral when any appliance, even a light is in use. Given the grounding you have described and assuming that the ground and neutral do not connect, your meter will show voltage between the neutral and ground anytime current is being used. That would be true in both barns. It should also show voltage between the hot and ground all the time in the first barn regardless of the switch setting. It should show voltage between the hot and ground in the second barn when the switch is on.

Confirm that the ground and neutral do not come together anywhere.

Is the main panel grounded? Given that the cable to the first barn does not have a ground wire, does your house wiring have ground wires?

I am thinking a bad neutral connection. Follow back through each box, checking polarity at each location, till polarity is correct, then back forward.

So am I Strat, but I can't quite fine logic that fits all the symptoms.

The panel back at the house was installed in 1993-94 after the previous house burnt down, according to the previous owner, and the new house is actually a mobile home, so this electrical panel is outside on a service pole. I think that the previous homeowner used the original barn wiring because there area junction boxes below the panel where the wires meet. As far as I can see the panel is grounded. I think what I am going to do is go into the second barn and just disconnect everything one by one until I can at least isolate the area in which the problem is occurring. Maybe the neutral connection underground between the two barns is bad?

**line 3 correction: there ARE junction boxes...

Kyle
What you are telling us is just too weird to be correct. Not that I don't believe you its just too weird. I've given a lot of thought to this and there is only one way that I can think of that cause what you say is happening to happen. That way requires multiple stupid things to have been done. Not by you but by the person that set up the wiring to the barn. The fact that you have junction boxes on the pole below the circuit panel makes me think that those stupid thing could have very well been done. You need to start at the circuit panel and check everything from there.First how about showing us a picture of the pole. Then remove the circuit panel cover and answer the following questions .

I am using a meter to do my voltage checks. Yes/No

I have a single 30 amp circuit breaker on the line to the barn. Yes/No

I have a 10 gauge 2 wire cable going from the circuit panel to the barn. Yes/No

The wires in that cable are, one black and one white, no ground wire. Yes/No

The black wire of that cable is connected to the circuit breaker. Yes/No

The white wire of that cable is connected to the neutral buss of the circuit panel. Yes/No

The cable goes to box in the first barn. Yes/No

The cable does not go through a junction box on the pole. Yes/No

A ground rod has been sunk and a ground wire has been run from the ground rod to the box with the 2 wire cable in the first barn. Yes/No

Describe the other wiring in the first barn. (in detail)

Don't guess or assume anything when answering these question, check and double check.

I will update as soon as I go up there.

I just don't understand why the hot and neutral are only reversed when I turn on the power to the second barn. And it just so happens there is a wasp nest inside the breaker box, so I am going to have to figure out how to take care of that...