Reverse polarity

[chuck741]

Put a 3rd camper hook up in. Seems to work fine, had a friend plug his camper in to see if everything worked fine, his surge protector showed ok. This was his first time using camper since buying it used. When he turned his water heater on electric it changed the surge protector to reverse polarity. When he shut it of it was fine. He has since been to some camp grounds but said it never did that at those. Any ideas. Thanks.

 

[Dan_Frisbie]

Check to see if his water heater is wired correctly.

 

[TonyL]

I wouldn't have thought that a straight resistive load would be polarity biased?

 

[Gary RV_Wizard]

I too do not understand how anything the water heater does could cause a reverse polarity error at the surge unit. What make/model unit is it? It should be checking the polarity of the power source, not the load. Also, is this hookup 30A or 50A?

 

[John From Detroit]

I do.. Screw loose..
Reverse polarity only happens on 30 amp hookups. not 50s (though it is possible it's very very very bad on 50s

You have 3 wires
Hot, Neutral, Safety ground
Normally Neutral and safety ground are bonded in one and only one place.. The first panel post meter.
So the Energy Monitor looks for voltage between Neutral and Ground.. If it sees it "Reverse polarity" iF you have a screw loose or some other issue. that can happen. I'd check the neutral first.

Another thing.. the 3 wires are normally arranged

Hot
Ground
Neutral
This means the ground if the bonded end is not properly connected.. will show 60 volts.. Check that screw.. next.

(It is called a capacitive voltage divider in electronics).

 

[bigb56]

Just like John said, a loose or open connection on the neutral will cause it when there is a load upstream of the test device. If all the current from the load cannot get back to the source on the neutral due to a compromised connection, the neutral will rise in potential. The test device now sees the voltage potential on the neutral which should normally be at zero or near zero and it lights the reverse polarity lamp which is connected to the neutral. Something is compromised and the water heater load exposed it.

I used to use my shop vac that I kept on the truck to help find loose or open neutrals because the motor load would put a decent load on the circuit and expose the weaknesses.

 

[Gary RV_Wizard]

I do.. Screw loose..
Reverse polarity only happens on 30 amp hookups. not 50s (though it is possible it's very very very bad on 50s

You have 3 wires
Hot, Neutral, Safety ground
Normally Neutral and safety ground are bonded in one and only one place.. The first panel post meter.
So the Energy Monitor looks for voltage between Neutral and Ground.. If it sees it "Reverse polarity" iF you have a screw loose or some other issue. that can happen. I'd check the neutral first.

Another thing.. the 3 wires are normally arranged

Hot
Ground
Neutral
This means the ground if the bonded end is not properly connected.. will show 60 volts.. Check that screw.. next.

(It is called a capacitive voltage divider in electronics).

All true, but the possible loose screw we are considering is in the water heater, not the power source. It's conceivable the water heater is using ground rather than neutral for its heat element, but if it was, it would cause the error wherever it is plugged in. The report here is that the problem occurs only at the OP's camper hook-up. And other campers work fine on that very same 30A hook-up. Very mysterious, in my opinion.

 

[Kirk]

When he turned his water heater on electric it changed the surge protector to reverse polarity.

Should we assume that said water heater is the 120V heating element and not the propane side?

a loose or open connection on the neutral will cause it when there is a load upstream of the test device.

It would help to know just what "urge protection device he is using, but all of the ones that I ma familiar with will show "open neutral" if the neutral is open. A loosed screw, maybe.

 

[bigb56]

They will show open neutral when the neutral is open with no load present, but when you introduce a L-N load ahead of an open neutral, the neutral section between the load and the break becomes energized and if the test device is on that section it will cause the reverse polarity lamp to light.

 

[Gary RV_Wizard]

He said "on electric", so we don't have to assume that.

Nor do I think an open neutral downstream from the "surge protection device" would cause any error, whether open neutral or something else.
I'd love to be there to run various tests to get more detailed facts.

 

[Gary RV_Wizard]

They will show open neutral when the neutral is open with no upstream load present, but when you introduce a L-N load ahead of an open neutral, the neutral section between the load and the break becomes energized and if the test device is on that section it will cause the reverse polarity lamp to light.

So there would have to be an upstream load? And we don't know where the surge device is in that RV, nor how it tests. "surge protection device" covers several possible types. Wish we had more facts!

 

[bigb56]

So there would have to be an upstream load? And we don't know where the surge device is in that RV, nor how it tests. "surge protection device" covers several possible types. Wish we had more facts!

Sorry no, I meant an upstream open neutral. To avoid confusion here is a sketch showing what I mean, you can see that an open neutral upstream of the load will energize (put a potential on) that remaining section of the neutral and if the test device is located anywhere on that now isolated section, upstream or downstream from the load, it will see that voltage on it's neutral connection.

 

[bigb56]

The proof that this is a compromised neutral is the fact that the test device suddenly goes from normal to reverse polarity when a load is applied. We all know that the polarity cannot reverse on it's own like that.

 

[Lou Schneider]

All true, but the possible loose screw we are considering is in the water heater, not the power source. It's conceivable the water heater is using ground rather than neutral for its heat element, but if it was, it would cause the error wherever it is plugged in. The report here is that the problem occurs only at the OP's camper hook-up. And other campers work fine on that very same 30A hook-up. Very mysterious, in my opinion.

It could be a loose screw or another kind of high resistance connection external to the water heater. Turning on the water heater draws a lot of current which creates voltage loss through the bad connection, raising the neutral above ground and tripping the reversed polarity alarm.

Like you said, the fault would have to be upstream of the monitor to raise the neutral voltage at the monitoring point.

This is different from a ground fault, shunting current to ground will affect the neutral current but not the neutral voltage at the monitor.

It would be informative to see if turning on another high wattage appliance like a room heater produces the same fault.

 

[John From Detroit]

All true, but the possible loose screw we are considering is in the water heater, not the power source. It's conceivable the water heater is using ground rather than neutral for its heat element, but if it was, it would cause the error wherever it is plugged in. The report here is that the problem occurs only at the OP's camper hook-up. And other campers work fine on that very same 30A hook-up. Very mysterious, in my opinion.

I's say that too is possible.. Though I'd like to think it is not likely I remember when I had central air installed and when we went to turn it on Pop went the fuse.. 3 times... (The poor tec was on his last fuse when we found the problem) the kid who wired it.. Put swapped the black and green wires on the load side. Yup. Fuses a popping all right. Thank heaven for the fuse. (Well NEC).

 

[gwinger]

Possibly the water heater element is touching the inside of the tank. Not a dead short, but may be enough to confuse the surge protector.

 

[Kirk]

They will show open neutral when the neutral is open with no load present,

All of the devices that I am familiar with open the power supply when an open neutral is present. What brands do not?

 

[bigb56]

All of the devices that I am familiar with open the power supply when an open neutral is present. What brands do not?

I don't know, the OP said it was a surge protector which is not the same as an EMS. Surge protectors don't stop power, they just absorb surges.

 

[TonyL]

Possibly the water heater element is touching the inside of the tank. Not a dead short, but may be enough to confuse the surge protector.

It's also possible that the element has blown and the water around the break becomes part of the element. As electricity takes the least path of resistance, it will only short to the other open end of the heater element and not to any flowing water.
Basically the water heater becomes an electrode boiler.

 

[Kirk]

Surge protectors don't stop power, they just absorb surges.

While I am well aware of that as a career tech, I also know that the vast majority of users call any such device a surge protector. In fact, there is a very well-known one whose brand name is Surge Guard. If the OP only had a surge protector as you suggest, how would it ever detect an open neutral, or any of the other things that you are suggesting?