Reverse Polarity Light when on Generator

Sounds like the gen 2 wiring may be reversed...when off inverters sometimes reverse the polarity, so when it's off everything appears normal, but then on startup the problem surfaces...

The wire to the rev pol light could be shorting...

That's what I was thinking, but I think the reverse polarity tester plug should have shown that. My next step, next time I work on it, I'm going to just use the Gen 1 circuit. And see what doesn't work. Then do the same with Gen 1. The seeming "randomness" leads me to believe, that it is indeed a stray current caused by some device somewhere. This is definitely going to incur an overnite to St T!!!

It would be interesting to see the configuration of the change over network that allows the 2 phase generator inputs - and inverters - to take over from the single phase shore input, ie. how have they isolated the two phases and made the single phase shore power then supply all items on board?

I'm a bit confused as to the purpose of RPIs on the genset, as they are normally there to guard against shore power reversal - the onboard connections, once done would not be expected to be able to be accidentally reversed and would therefore not require RPIs

The two phase output from the genset will probably have a common neutral, and the RPI would be connected between the neutral and ground, so a reverse polarity would more likely be evident on both phases, so, without access to a cct diagram it's hard to interpret what is occurring.

Having said that, reverse polarity indicators should have at least 25K ohms of series resistance to prevent stray currents causing spurious indication of a fault - are you satisfied that all of your indicators have this resistance.

You state that the light is only dim, so it is possible that stray currents rather than a true fault are the cause. Maybe you could try increasing the resistance to see if that helps.

I'm not sure what you mean in your last paragraph where you suggest supplying the inverters from the generators - do you mean via suitably sized DC chargers, as the inputs to the inverters would be DC not AC, and most likely down around 12V or so.

All good points, especially these. It would be interesting to see the configuration of the change over network that allows the 2 phase generator inputs - and inverters - to take over from the single phase shore input, ie. how have they isolated the two phases and made the single phase shore power then supply all items on board?

I'm a bit confused as to the purpose of RPIs on the genset, as they are normally there to guard against shore power reversal - the onboard connections, once done would not be expected to be able to be accidentally reversed and would therefore not require RPIs

The two phase output from the genset will probably have a common neutral, and the RPI would be connected between the neutral and ground, so a reverse polarity would more likely be evident on both phases, so, without access to a cct diagram it's hard to interpret what is occurring.

It is split, not two phase, and the "center tap" of the genset does go to ground.

Having said that, reverse polarity indicators should have at least 25K ohms of series resistance to prevent stray currents causing spurious indication of a fault - are you satisfied that all of your indicators have this resistance.

I will indeed check that

You state that the light is only dim, so it is possible that stray currents rather than a true fault are the cause. That is what I'm thinking, and hope not. There is an outdoor fridge, ice maker, with outlets for a blender etc. Stray currents could be lethal.

Capacitive coupling is the likely culprit, two wires run next to each other for a distance, one with ac, will couple enough current to light a high enough impedance lamp. If you do have reverse polarity, the lamp will come on full brightness. A loading resistor across the lamp will make the lamp dimmer, if it is really bothersome.

Thank you: I sort of agree with your diagnosis. Any ideas as to why it only appears on one of the RPL's?

I have contacted Northern Lights...........awaiting there response. Didn't even get a "do not reply we will respond within 1-2 business days".

My guess would be the routing of the wires, one closer to a hot lead than the other, or longer...(?). Possibly a difference in the indicator manufacturing tolerances, don’t know if you can interchange them...

I am confused by your term 2 phase. My house (like most United States houses) has single phase power. Two hot wires and a neutral. Voltage from either hot to neutral is 115 volts. Voltage between two hots is 230 volts. Is this what you refer (not exactly correctly) to as 2 phase?

No sir, someone else did. What you, me, and the boats generator are is "split phase". Two phase is like three phase, but is/was used in lighting circuits. Three phase has the phases 120 degrees separated, two phase is 90 degrees.