Reverse Polarity Light Illuninates When water Heater CB is Closed.

[Rees]

I don't use my water heater heating element very often. I recently used it while on a marina overnight, and became concerned when pushing in the circuit breaker and noticed the reverse polarity light came on immediately, tho not especially brightly.
A couple additional points. I did replace the light about 6 months ago. I checked wiring: one connection to the neutral (white wire and the other to green (ground). I checked voltage with the breaker closed at 3 volts, 2.7 amps.
When the water heater CB is pulled out the voltage is 0 and the light goes out.  An inspection of the water heater panel revealed, it appeared to be wired correctly, all connections clean, securely connected.  Why would this reverse polarity light be on?  Idea on how to correct the problem?

A non marine electrician friend suggested that I switch the wires (black and white) and see if the light goes out. 

[Jim Hardesty]

I'm not an electrician or do I have a great understanding of the reverse polarity indicator.  I have had dim reverse polarity light.  I've been able to eliminate the light by cleaning up the connections. If any of the connections are by crimped connections check them very carefully, a good tug on the wire.
I found a couple of bad factory crimped connections on Shamrock.
Jim