A/C circuit only works on Shorepower

[Midnightsun]

Not familiar with the build of the auto transfer switch however it must be a dual pole contactor (1 for SP1 and 1 for SP2) that gets energized and sends power to each shore power main panel breaker switching between pedastal and genny depending on source selected which energizes or deenergized the contactor.

That being said these contactors with time do wear out the actual contacts through arcing so my best guess is the contacts on the AC side are now toast and in need of a replacement. This will give you an idea of what I am referring to. https://sparetek.com/products/relay-dpdt-30a-120v

[bud37]

Yes, I agree the line 2 contacts are likely damaged....now where that switching device is located on the boat is in question but the main lines to the panel would be my guess. Like I was saying there has to be a device in the 120vac lines to isolate the boat from shore power when the gen is selected if it is all automatic, or at least there should be to keep any back feed to shore from happening.

Hopefully if he finds it he can fill us in on the details for someone else if it arises again.

[buster53]

On my boat, the auto transfer switch is directly behind the electric panel. Makes sense for it to be there no matter what model boat you have.
Just takes removing a couple of screws and you are there, easy peasy.

[km1125]

Source of the post Not familiar with the build of the auto transfer switch however it must be a dual pole contactor (1 for SP1 and 1 for SP2) that gets energized and sends power to each shore power main panel breaker switching between pedastal and genny depending on source selected which energizes or deenergized the contactor.

That being said these contactors with time do wear out the actual contacts through arcing so my best guess is the contacts on the AC side are now toast and in need of a replacement. This will give you an idea of what I am referring to. https://sparetek.com/products/relay-dpdt-30a-120v

Actually on a boat you need to have three contacts. As you say one for each SP1 and SP2 but then you also need a contact to establish a connection between neutral and ground when the generator (or inverter) is supplying power. When you're getting power from the shore connection, you DO NOT want a connection between neutral and ground done at the boat (that would be done at the shore power main panel).

[AC3207]

Is there a chance that its built into the 3 bay main circuit 2 breaker shown in photo? The reason I ask is when I purchased the boat the broker mentioned it had just had a breaker replaced. He mentioned it was an off type and took a while to get I also think he may have mentioned something about transfering. The circuit 1 main breaker looks new.

[km1125]

Source of the post Is there a chance that its built into the 3 bay main circuit 2 breaker shown in photo? The reason I ask is when I purchased the boat the broker mentioned it had just had a breaker replaced. He mentioned it was an off type and took a while to get I also think he may have mentioned something about transfering. The circuit 1 main breaker looks new.

Definitely not the one you showed in that photo. That's a standard breaker with reverse polarity protection used on many vessels of this vintage. If you can follow the wires that go TO that main breaker (or the main breaker for Circuit #1), that would lead you to where the auto transfer relays are. And/or follow the power circuits leaving the generator because they might go to a separate box (where the auto-transfer relays are) before they head to the main electrical panel.

[AC3207]

Understood. Ill start there. Thanks.