Reversed Polarity Issues?

[Speedogomer]

I ordered a simple voltage monitor for testing power supply at campgrounds. Reads voltage, and if there is correct polarity, or open ground.

My parents own part of a small lake, that they've made into a sort of private campground. They have electricity run there, with 3 different 30amp connections. Today I brought my TT there to have it ready for our annual 4th of July celebrations and decided to use my voltage monitor. Voltage was fine 120 volts reading, but it read reversed polarity on all 3 hookups. The lone 20 amp standard outlet read correct polarity.

We've had several RV'S connected there for 2 years. Never had an issue at all. My parents RV is there most the summer. My question is what sort of issues can reversed polarity cause? I'm hoping my voltage monitor isncorrect, because today we switched the hot and neutral wires on all the hookups so they now read correct polarity.

[Bobbo]

Tom/Barb wrote:
how can you have reversed polarity in a AC circuit? it reverses every 60 milliseconds....

Wiring without reversed polarity, GROUND and NEUTRAL have 0v between them.

Wiring with reversed polarity, GROUND and NEUTRAL have 120v between them.

Don't even consider reversed polarity bootleg ground!

[Gene_Ginny]

Old-Biscuit wrote:
Reverse polarity on AC power means that the Hot & Neutral have been switched.

Turn off an AC circuit breaker and you interrupt the hot side.........but if reversed the neutral is hot and would still be energized. Not good from maintenance safety point.

Fix it before somebody gets electrocuted working on a hot circuit

Well said, simply stated, and to the point ... alas, not everyone reads.

Tom/Barb wrote:
how can you have reversed polarity in a AC circuit? it reverses every 60 milliseconds....

[wa8yxm]

I will give you 3 scenarios

1: You are plugged in to an outlet with a DOUBLE INSULATED power tool and there is a neutral to case short.. Normal or reverse polarity, NOTHING bad happens. since its double insulated. YOu are safe

2: Tool is not double insulated, and some idiot broke off the 3rd pin.. Been nice knowing you.. Depending on several things you could easily be dead if it's reverse.. Normal no damage.

3: HOT wire to case, as in 2,, but normal polarity, Same as 2.

HOT wire to case, 3-rd pin present and propely grounded, CLICK of darkness (Breaker trips) you are safe.

GFCI, may not work if reverse connected and thus may not protect you.

TRUE STORY:
Bought a trailer, 20 amp twist lock, inlet,, Prior owner made his own adapter,, Well he reversed both it and the extension cord he made it from (He cut the plug end off an extension cord and put a new plug on what's left and the twist lock socket on the pig-tail)

Plugged in with his cord, Rverse-Reverse = normal so it worked fine

Plugged in with MY 12ga 100'er.. Liked to knock me on my ... er... pride.

Things that should have been at ground were, in fact, 120 volt.. But the safety ground meant some things were at ground.. Like the metal sink.

Finally I fixed the adapter.. Then I used HIS cord and .. Fixed it.

[myredracer]

The reversed polarity condition should be corrected immediately because of risk of shock and fire. It is easy to fix.

Correct, reversed polarity does not cause a breaker to trip.

Receptacles downstream of a GFI recept. will still work and be protected, but the GFI recept. will still work but not provide GFI protection for that recept. only. The test button on the GFI recept. will still work though and will not give any indication that the hot and neutral are reversed. Reversed polarity and GFI receptacles

In AC circuits, the neutral is bonded to ground at the main panel in your house (or at CG) and never downstream of the main panel. You should be able to touch any neutral conductor in your house or RV and be safe. With reversed polarity, this is not the case.

Having the neutral bonded to ground is very important. Nowadays, kitchen appliances, power tools, etc. have a polarized plug so that you cannot reverse the polarity. This prevents the outer enclosure/casing from being hot if there is an internal fault or defect in the wiring. If an appliance or tool does not have a polarized plug, it will have a double-insulated enclosure. If you look at a plug, one prong is wider which is the neutral. Appliances and tools that have a switch on them turn the hot conductor on and off and with reversed polarity, it will still be energized and potentially dangerous. Further, with reversed polarity, some appliances may burn out if it is left plugged

If you have reversed polarity at your RV, you could end up with a "hot skin" condition where the exterior of the RV is at 120 volts. This obviously can be dangerous and has been known to be fatal. The only way to test for a hot skin is to use a non-contact voltage tester. Any other tester will not indicate this condition.

Mike Sokol on the hot-skin condition

Some general info. on reversed polarity:

Reversed poloarity

[Rvpapa]

And that is a good example of one of the reasons Neutral & Ground are NOT bonded in an RV.
Art.

[Altern]

Read all about polarity right HERE

[Wayne_Dohnal]

Polarity has a different meaning on AC power circuits than with DC circuits. On the AC circuit, one conductor (white wire) is grounded and does not have overcurrent protection. The black conductor (and red in a 240 volt circuit) is called the "hot" and has overcurrent protection. Reversed polarity does not cause a breaker to trip, and in fact could prevent a breaker trip in some situations. If a white wire gets shorted to ground with correct polarity, little or no current will flow. If a white wire gets shorted to ground with reversed polarity the wire is subject to a large overload which could start a fire.

When an RV is plugged into an outlet with reversed polarity everything will most likely operate normally, but several safety mechanisms will be defeated increasing the risk of fire and personal injury.

[Tom_Barb]

Old-Biscuit wrote:
Reverse polarity on AC power means that the Hot & Neutral have been switched.

In reality, that will blow the circuit breaker as soon as it is connected.

[Tom_Barb]

how can you have reversed polarity in a AC circuit? it reverses every 60 milliseconds.

You can have out of phase. where one of the hot legs is attached to a ground. That usually shows up quickly and for a short time. 🙂

[Speedogomer]

Thanks for the input. As noted in my original post, we corrected the issue already. Glad that my voltage monitor came in handy the very first time I used it.

[Old-Biscuit]

Reverse polarity on AC power means that the Hot & Neutral have been switched.

Turn off an AC circuit breaker and you interrupt the hot side.........but if reversed the neutral is hot and would still be energized. Not good from maintenance safety point.

Fix it before somebody gets electrocuted working on a hot circuit

[ScottG]

Can be dangerous in the event of a failure in something like the water heater or fridge. Also I don't think the GFCI's will function correctly.
I would open them up and swap the connections on the back of the outlets. It's easy and there's no sense in keeping it wrong.

[Gale_Hawkins]

Seldom is it ever an issue but it was good to correct before you did have a problem. In my view it is more for safety. A lot of battery back up for computers will test for this and people did not even know about the wiring issue.