Portable Generator spewing Reverse Polarity

[Raylee]

This is not exactly a built-in generator questions but I was hoping to get some feedback, if I may. I have a portable genset 3200watts with a 30amp outlet. It’s my backup unit that I exercise every year and occasionally use for hours to runout leftover dinghy gasoline & take hrs off the main genset, at the end of the season.

It has always worked reasonably well but this year, the boat’s breaker panel is showing Reverse polarity. I realize that some generators have a “ floating neutral” which can trigger the Reverse polarity light, but this generator has never done that in previous seasons. Some troubleshooting sites talk about using an adaptor. I am not site what sort of an adaptor I need.

I would appreciate any feedback or guidance.

Thank you much

Raylee

 

[nussbda]

Search on Amazon for "Neutral Ground Bonding Plug" for use on floating ground portable generators.

Dave

 

[Don L]

I have had the connections for a portable generator go "bad". You have a connection somewhere that has probably corroded.

 

[jgwinks]

Search on Amazon for "Neutral Ground Bonding Plug" for use on floating ground portable generators.

Dave

Or make your own. It's just a 3 wire plug with the ground (green) and neutral (white or silver colored) terminals connected with a short piece of wire. The hot terminal (black or brass colored) doesn't get connected to anything. Plug this into the other outlet on the generator.
The reverse polarity light comes on if there's a voltage difference between the neutral and ground and bonding them at the generator keeps this from happening. This is in fact an ABYC requirement. Why it suddenly started coming on when it didn't before I don't know. It could be just what you have plugged in and running made the difference.

 

[O C Diver]

I would start with verifying that you are getting reverse polarity. If you have a volt ohms meter (VOM) it's pretty easy to check the plug on the generator with it running. If it also has a normal house duplex outlet, most hardware stores, Lowes, and Home Depot sell a simple plug to check polarity and ground.

Ted

 

[l00smarble]

Assuming generator has or had a neutral to ground bond since it never caused this light before. If it lost this connection you need to figure out why and fix it or use one of the plug adapters like someone mentioned.

So if the gen has N-G bond I’ll guess the RP light is glowing but not full brightness. 90% chance this is caused by a higher than normal resistance in the neutral conductor somewhere between genset outlet and your AC panel. If it only happens on gen and not shore the cause will be your cord or plug or adapter that you are using with your genset. Whatever cord situation you are using different from what you use for regular shore power. You may find a corroded connector or loose terminal or mechanically failing cable.

The reason for the light is the high resistance causes a voltage drop or voltage difference in the neutral conductor from your panel to the panel/meter on land where neutral is literally connected to ground to hold it at ground potential.

N on board no longer held tightly at ground potential so if you measured with an AC voltmeter in you panel you will see a few AC volts between N and G. This can be enough to make the light glow.

 

[Raylee]

Thank you all very much for the comments snd information. I opened the generator, cleaned & tightened all the electrical contacts.. I did not see any corrosion, in fact the inside of the genset looked very clean. the genset internal ground connection was a bit loose. I measured the voltage between ground & neutral at the cable prongs that plug-into the boat 30amp inlet. it was very near/almost zero.

I then connected the cable back to the boat.. still getting the reverse polarity indication in the breaker panel for line 2. I switched the connection to line 1 and received no reverse polarity light. So at least that works. I will open the line 2 power inlet as well the breaker panel section for line 2 and see if I can identify a loose or corroded connection, once we are back to the dock.

Thank you all again for the great ideas and help

Raylee