Why neutral and hot reversed only when a/c is turned on?

[jdgasoline]

I have tenants that have 3 fairly new small a/c units all the same and when any of them are turned on my tester reads hot & neutral reversed. The 15 amp circuit that feeds these units has no ground wire. Is this normal or could these a/c units be wired wrong from the factory?

 

[Pete999]

Induced emf maybe

 

[pc1966]

The 15 amp circuit that feeds these units has no ground wire. Is this normal or could these a/c units be wired wrong from the factory?

Do you mean the circuit in the house has no ground? I would be surprised if that is allowed in the USA!?

I would be more ccncernd there is something wrong with the house wiring, maybe a high resistance neutral or similar, and suggest you get a professional electrician to check it more thoroughly than a socket tested does.

 

[jdgasoline]

Do you mean the circuit in the house has no ground? I would be surprised if that is allowed in the USA!?

I would be more concerned there is something wrong with the house wiring, maybe a high resistance neutral or similar, and suggest you get a professional electrician to check it more thoroughly than a socket tested does.

It is not allowed in the US I juust found out when I rehabed the apartment .The wiring was updated about 12 years ago for these 3 rooms so all of the new wiring has a ground other than the line that comes from a junction box and I am going to be running a new line with a ground in a couple days. It was the reversed hot & neutral that I wasn"t sure about. Why is this happening?

 

[James]

if the circuit they are connected to has no ground connection, it may well be against reg's.
@Megawatt will be better to advise on that.

however, if there is no ground reference, your tester is unlikely to be able to be able to accurate information about hot and neutral being reversed as it uses the ground to reference the voltages against.

 

[Megawatt]

I have tenants that have 3 fairly new small a/c units all the same and when any of them are turned on my tester reads hot & neutral reversed. The 15 amp circuit that feeds these units has no ground wire. Is this normal or could these a/c units be wired wrong from the factory?

Gasoline all you need to do is take the receptacle out and the black wire goes on the gold screw and the white goes on the silver screw. That’s where your polarity is crossed
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I have tenants that have 3 fairly new small a/c units all the same and when any of them are turned on my tester reads hot & neutral reversed. The 15 amp circuit that feeds these units has no ground wire. Is this normal or could these a/c units be wired wrong from the factory?

As far as the absence of a ground yes a lot of old houses don’t have grounds from many years ago and as far as code enforcement goes if you replace the receptacle or light or anything you have to install a ground wire from the panel. Anything you work on you have to bring it up to code.
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I have tenants that have 3 fairly new small a/c units all the same and when any of them are turned on my tester reads hot & neutral reversed. The 15 amp circuit that feeds these units has no ground wire. Is this normal or could these a/c units be wired wrong from the factory?

I worked on a house yesterday that had no ground and it was the old cloth insulation wire. I had to go up in the attic and replace the old wiring to bring it up to today’s standards.

 

[davesparks]

It is not allowed in the US I juust found out when I rehabed the apartment .The wiring was updated about 12 years ago for these 3 rooms so all of the new wiring has a ground other than the line that comes from a junction box and I am going to be running a new line with a ground in a couple days. It was the reversed hot & neutral that I wasn"t sure about. Why is this happening?

How are you testing this apparent polarity reversal?

I don't see how you can test polarity without a ground to use as a third point of reference.

If you measure between hot and neutral you will see 120V (if I understand USA terminology and voltages correctly) if you swap the leads of the tester you will measure exactly the same voltage. AC doesn't have an easily established polarity the same way DC does, it is only when you bring a third point of reference into the measurements, such as a ground, that you can establish a polarity.
Once you have a ground you can measure between hot and ground, then neutral and ground to establish which one is at ground potential and which one is at 120V to ground.

If it is a tester, such as a socket tester, which connects to hot, neutral and ground then gives simple results such as OK, polarity reverse, missing neutral etc then being totally without a ground it will lijely be confused and behave erratically.
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Gasoline all you need to do is take the receptacle out and the black wire goes on the gold screw and the white goes on the silver screw. That’s where your polarity is crossed

We don't know for sure that the polarity is wrong, we only know that there is no ground and an unknown type of tester has indicated a wrong polarity. This could easily be the tester being unable to function correctly without a ground and giving a false reading.

 

[jdgasoline]

Gasoline all you need to do is take the receptacle out and the black wire goes on the gold screw and the white goes on the silver screw. That’s where your polarity is crossed
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As far as the absence of a ground yes a lot of old houses don’t have grounds from many years ago and as far as code enforcement goes if you replace the receptacle or light or anything you have to install a ground wire from the panel. Anything you work on you have to bring it up to code.
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I worked on a house yesterday that had no ground and it was the old cloth insulation wire. I had to go up in the attic and replace the old wiring to bring it up to today’s standards.

I checked all receptacles on that circuit and they are all wired correctly black wire to gold screw and white to silver screw and hot is black wire. Like I stated in first post the tester reads fine other than no ground (which I will be running a new 14awg wire so that issue will be corrected) but the hot and neutral reversed is what I was concerned about it only reads on tester if the a/c units are running
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Sorry I did not know if the no ground issue was the cause of the problem. \
and this is the tester that I am using

 

[Lucien Nunes]

As above, the lack of a ground wire in the circuit is confusing the tester. It might indicate OK with the A/C's switched off, but when you switch them on, the normal small amount of ground leakage coming back down the cord to the outlets that has nowhere to go, makes the ground prong partially hot. The tester sees too high a voltage between what is supposed to be ground and neutral, and too low between ground and hot, and interprets this as a reversal of hot and neutral.

 

[jdgasoline]

Thank You everyone for the replies! I will replace ungrounded wire and test to see if that was the issue.