Question: I’m looking at a vintage 1960s 38 foot Concord motor cruiser that I would like to restore. My surveyor noticed that there are a few AC outlets on the boat that have only two slots, just like old houses. He says that they should be replaced and a three wire grounding system will also need to be installed to bring the boat into compliance with current standards. My question is, these things have worked well for over forty years and I have a variety of two pronged plug electrical devices, like my cell phone charger that I can plug into this type of receptacle. Why should I bother changing them?
Answer: The short answer here is that you could save someone’s life by updating the boat to a grounded system. The reason the three prong plugged systems in houses became mandatory is that the grounding circuit can be a real life saver. And it’s even more important on boats due to the damp environment.
The third prong acts as the alternate path for current flow back to the power source for any electrical short circuit that develops in an appliance. This will facilitate tripping the circuit breaker that supplies power to the outlet.
I strongly suggest you get an estimate from a certified marine electrician to upgrade the boat, and build the cost into negotiations for the purchase.