Reverse polarity when powered by aux generator

[3rdOrderEffect]

Ok, I am stumped here, altho I suspect I am missing something simple.

My boat has a diesel genset that works fine. When powering the boat via the genset, I do not get a reverse polarity indicator on my selector panel or the ac breaker panel.

When I plug into shore power (boat uses 30A), I do not get reverse polarity indication either (has worked fine at every marina I’ve been to).

Now when I plug into the auxiliary inverter generator I bought to backup the main genset, I get a reverse polarity indication no matter how I wire the adapter. I am using this adapter to convert the generator’s TT-30P output to the boat’s L5-30R shore power cord

I have ensured the female side of the adapter that the shore power cord plugs into is wired to standard

But because I was getting reverse polarity indications I rewired it with line and neutral swapped and got the same results. I swapped it back.

When powered off this inverter generator, I immediately get a reverse polarity indication on the ac selector panel (right side of photo), but I get polarity ok on the ac breaker panel (left side of photo). However when I turn on the battery charger, I now get reversed polarity on both panels. Again, this happens no matter how the adapter is wired

What am I missing here?

 

[SteveK]

Have you used a voltmeter and with shore cable plugged in identified the outlets, then compare to the gen outlets to see if they agree with your drawing?
2nd thought, shore, inverter and main GEN have ground & neutral bonded. Maybe the portable one does not bond these and that results in the reverse light.

 

[3rdOrderEffect]

Have you used a voltmeter and with shore cable plugged in identified the outlets, then compare to the gen outlets to see if they agree with your drawing?
2nd thought, shore, inverter and main GEN have ground & neutral bonded. Maybe the portable one does not bond these and that results in the reverse light.

I think you are on to something.

I should mention that I am using a 4kw inverter generator, but I also got the same result with my 2.2kw inverter generator using a 15A to 30A adapter. At the time I figured it was the adapter, and I needed more power to run everything anyway, so I got the 4K since it had a 30A out already.

The neutral on the gen is floating, stated on the panel:

I guess the question remaining is, is it safe to run, and if not what do I have to add/check/change to make it safe?

 

[CharlieO.]

I wonder if one of these would help?

Generator Bonding Plug

Generator Bonding Plug Finally, a simple solution for a simple problem with your RV portable generator and its power/surge protector. Some RVs have built-in power/surge protectors or some owners choose to use their pedestal plug-in power/surge protectors even when operating on portable generator...

www.microair.net

 

[SteveK]

Floating means ground and neutral are not internally connected.
Where the supply line goes into the generator open it up and if not obvious post a picture. You just need to add a jumper wire between neutral/ground or move them to one post.
Your problem should be solved

 

[SteveK]

I wonder if one of these would help?

Generator Bonding Plug

Generator Bonding Plug Finally, a simple solution for a simple problem with your RV portable generator and its power/surge protector. Some RVs have built-in power/surge protectors or some owners choose to use their pedestal plug-in power/surge protectors even when operating on portable generator...

www.microair.net

Yes that would work too, but OP can also bond inside the adapter cord he posted, as long as it is not used anywhere else.

 

[3rdOrderEffect]

Thanks guys, understanding the problem helped me find a lot of guidance via Google. Turns out about everyone who runs an inverter gen on a boat runs into this problem and then heads to a forum to ask why