Not sure of your equipment, configuration or your order of doing things but it is possible to not encounter a reverse polarity situation even when the shore power or power cord is wired wrong. I always have all loads and breakers OFF before ever bringing shore power into the boat. Then I gate power one leg at a time from the pedestal source to the eventual 120V AC load (coffee pot, whatever). By doing this I am afforded the opportunity to look at my AC Selector Switch BEFORE any load can cause a problem. The switch will indicate if your Shore power is wired backwards (Reverse Polarity). It also allows me to pinpoint which load causes a problem because they will come on one at a time.
So my routine is this:
- Make sure nothing that runs on AC power is plugged in or ON.
- Make sure the AC main panel breaker is OFF.
- Make sure the AC Source Selector Switch is in the OFF position.
- Make sure Pedestal power is OFF.
- Plug in Shore power cord to pedestal and then to boat.
- Turn ON the power at the pedestal.
- Check the Reverse Polarity lights on the AC Source Selector Switch.
- If the indicator lamp is Green then you have the correct polarity and can then set the switch to Shore Power, turn ON the main AC panel breaker and start turning individual 120V breakers ON for your loads.
- If the indicator lamp is RED you have reverse polarity. Immediately turn OFF the pedestal power, unplug your power cord, and alert the marina staff.
Its a bit OCD but the last thing I want to deal with is fried wires that can't be reached or worse a fire.
HTH, Gary