a/c main breaker

[Dunstaffnage]

I am re-installing the original electrical panel in my Endeavour 40.
The panel is designed for 30A service but I am going to upgrade to 50A.
The original main breaker is 30A 3 pole.What is the 3rd pole for?


Any ideas?


There was originally a genset installed but it has been removed, may be replaced by solar depending on the coin toss.
The only thing I can think of is the 3rd pole was ground possibly related to genset usage.

[s/v Jedi]

Originally Posted by Dunstaffnage

I am re-installing the original electrical panel in my Endeavour 40.
The panel is designed for 30A service but I am going to upgrade to 50A.
The original main breaker is 30A 3 pole.What is the 3rd pole for?


Any ideas?


There was originally a genset installed but it has been removed, may be replaced by solar depending on the coin toss.
The only thing I can think of is the 3rd pole was ground possibly related to genset usage.

You will need to post a picture or a link to the exact breaker you have.

[Statistical]

Originally Posted by Dunstaffnage

I am re-installing the original electrical panel in my Endeavour 40.
The panel is designed for 30A service but I am going to upgrade to 50A.
The original main breaker is 30A 3 pole.What is the 3rd pole for?


Any ideas?


There was originally a genset installed but it has been removed, may be replaced by solar depending on the coin toss.
The only thing I can think of is the 3rd pole was ground possibly related to genset usage.

Ground should never be switched. Entirely possible that was done because a lot of wrong stuff are done on boats but you should not repeat it when cleaning things up.

Was your connection 120V or 120V/240V?

If it was 120V/240V then you will have 3 lines (hot1, hot2, and neutral). There is nothing wrong with switching all three although I am unsure if ABYC requires it. While only the two hots "should" be energized having 3 pole for 120V/240V ensures that if you have reverse polarity due to bad dock wiring and the neutral is hot that it is switched off too. Three pole breaker will completely isolate your main panel from shorepower with the exception of safety ground.

If it is just 120V 30A now being upgraded to 120V 50A then there is no point to a 3 pole breaker. Replace it with a 50A 2 pole breaker.

Since you are redoing everything anyways and will need to redo the inlet do the right thing and protect your boat and crew and put into an ELCI as close to the shore power inlet as possible. They are available in both 2 & 3 poles at 50A. Again ground is never switched. There should be a connection unbroken by switches/fuses/breakers from the shorepower pedestal ground to your main ground busbar. For completeness although it doesn't apply the only exception would be if using an isolation transformer.

[Bycrick]

I worked on an Island Packet once that had a burned. 3-pole AC breaker. The third "pole" was actually connected between the neutral wire and earth ground. If you had "reversed polarity" it would trip the circuit breaker. We had to buy the breaker from IP.

[smac999]

some old boats had a 3rd "pole" for the ground wire to measure and trip on reverse polarity. it didn't actually break the ground though, and tripped on voltage not amps.