Why Am I getting Reverse Polarity Message?

[Lakejumper]

In the past, I have plugged my RV in directly to my 30 receptacle in the garage, without a surge protector an without any issues. Today a friend who is visiting plugged into my 30 amp plug, but placed a surge protector in the middle of the power cords and got a Reverse Polarity error code. Why is this happening?

[uchu]

Test your garage outlet with a polarity tester. Something like this one:

https://www.amazon.ca/Klein-Tools-RT...s%2C271&sr=1-4

Or tell your friend to connect his surge protector to the outlet without plugging his power cord to it. That way you'll see if the issue is at your end or not.

[twinboat]

If you have a multi meter, set it on AC 150 volts range and follow the power.

Start at your outlet, then down the cords.

The red triangle shows what you should see with your meter.l

[Isaac-1]

A bad /marginal ground connection can also cause those surge protectors to read reverse polarity sometimes, still something you need to check on / fix.

[SKP Kirk]

I suspect that your outlet has the power lead and the neutral lead reversed. It wouldn't show without the line protection device but it is dangerous.

[Lakejumper]

Thank you to all for your reponses. I will check with a polarity checker. We, our friends and us, had to evacuate due the fire I. Santa Rosa, CA. I will check it when we return.