Electrical Gremlins

[JebLostInSpace]

So I suspect I'm at the point where I need to just hire an electrician and let a pro deal with this for me. But I thought I'd at least try to describe my issues here and see if somebody smarter than me thought it was easy and/or obvious...



So I have two 30A shore power lines into the boat. One goes to circuit A, which powers my battery charger, outlets, microwave, etc. The other goes to circuit B, which powers the air conditioner. Circuit A can also be powered by the generator, and circuit B can accept generator power via a switch I don't understand very well, labelled "Parallel A and B." I can run everything I want simultaneously on the generator right now with no issues.

The issue is when I use the shore power. I can only energize either circuit A or circuit B. When I try to energize both, the circuit A breaker trips immediately, before applying any load. I also sometimes get a concerning spark when this happens.

Also, each circuit has a "Reverse Polarity" indicator light, which I understand is meant to warn me if I have a positive/negative mismatch in the wiring somewhere. One or the other of these lights will come on when I try to energize both circuits using the shore power. These lights never come on when I energize only one of the circuits at a time. This bit really doesn't make sense to me, since there's clearly not a wiring problem (no changes to the wiring and the system worked fine for years before now). So something else must be causing these indicator lights to come on.

Does anybody have any helpful insight based on this? I'm currently using only circuit A most of the time, and occasionally switching over to circuit B to run the air con for an hour or so. It makes me nervous to continue using the system in this way since there's obviously a problem. I'm just not at all sure where to start.

I should also note, this is a problem that first occurred shortly after arriving at a new dock, but didn't start immediately at the new dock. I'm not sure how suspicious I should be of the power supply, or if that could cause a problem. The two 30A cables are coming from a single 50A source via a splitter. I can't quite reach any of the other power pedestals from my slip to test that, but if needed I can move to another slip temporarily.

[JebLostInSpace]

Forgot to add a picture to the original post of the panel. The "Reverse Polarity" indicators are circled in blue. One or the other usually comes on, seemingly at random, when I try to energize both sides. The two main breakers I'm using to energize are circled in red.

[sailorboy1]

[QUOTE=JebLostInSpace;3633472

The issue is when I use the shore power. I can only energize either circuit A or circuit B. When I try to energize both, the circuit A breaker trips immediately, before applying any load. I also sometimes get a concerning spark when this happens.

Also, each circuit has a "Reverse Polarity" indicator light, which I understand is meant to warn me if I have a positive/negative mismatch in the wiring somewhere. One or the other of these lights will come on when I try to energize both circuits using the shore power. These lights never come on when I energize only one of the circuits at a time. This bit really doesn't make sense to me, since there's clearly not a wiring problem (no changes to the wiring and the system worked fine for years before now). So something else must be causing these indicator lights to come on.

Does anybody have any helpful insight based on this? I'm currently using only circuit A most of the time, and occasionally switching over to circuit B to run the air con for an hour or so. It makes me nervous to continue using the system in this way since there's obviously a problem. I'm just not at all sure where to start.

I should also note, this is a problem that first occurred shortly after arriving at a new dock, but didn't start immediately at the new dock. I'm not sure how suspicious I should be of the power supply, or if that could cause a problem. The two 30A cables are coming from a single 50A source via a splitter. I can't quite reach any of the other power pedestals from my slip to test that, but if needed I can move to another slip temporarily.[/QUOTE]


I have the same boat:

1 - I have never connected SP to SP-B and have always run everything via the A bus and the parallel breaker. You do need to be aware of the total loads

2 - the SP A &B breakers will trip on overcurrent, but the breaker in the stern lock under the plug should trip first. But those breakers are also trip paks and trip if there is a current between the common and ground. That also will make the reverse polarity light come on.

3 - if using a splitter the lines should be that same on the buses, but have you tried switching them?

4 - if you leave Bus A SP breaker open and shut bus B SP does the breaker stay shut and the polarity light stay off?

I think you have problem in the bus B SP system

[JebLostInSpace]

Originally Posted by sailorboy1

I have the same boat:

1 - I have never connected SP to SP-B and have always run everything via the A bus and the parallel breaker. You do need to be aware of the total loads

2 - the SP A &B breakers will trip on overcurrent, but the breaker in the stern lock under the plug should trip first. But those breakers are also trip paks and trip if there is a current between the common and ground. That also will make the reverse polarity light come on.

3 - if using a splitter the lines should be that same on the buses, but have you tried switching them?

4 - if you leave Bus A SP breaker open and shut bus B SP does the breaker stay shut and the polarity light stay off?

I think you have problem in the bus B SP system

Thanks for the reply!

1 - I can successfully use the parallel breaker to run the air con while bus A is energized. I know from previous experience that I can't run the microwave and air con at the same time this way, but that's okay.

2 - I'm not quite following you on this one. Sorry, I'm quite a newbie on electrical work. The breakers in the stern locker are the ones that should trip if there's current between common and ground? Or did you mean the panel breakers should trip in that situation? The panel breakers trip every time I try to energize both sides. The circuit A breaker in the stern locker also trips sometimes, but not every time.

3 - I have tried switching which line is plugged into which port on the boat. This produces no change in the behavior.

4 - I'm not following you on this one either. Are we talking about the breakers in the stern locker or the breakers on the panel? I'm also reading "shut" as being in the "on" position, but I'm not sure if that's what you meant. But I can have Bus A powered on through SP, or Bus B powered on through SP. But if either A or B is on, then turning the other side on causes the breakers to trip. If I shut one side off, then turn the other side on, there is no problem.

[CarlF]

Shore power at a US marina is 240v with two 120v wires in opposite phases (two hot, one neutral, one ground wire) . A 50amp 240v cord uses both 120v wires. A 120v cord uses one hot wire and the neutral. The two 120v can not be connected together because of the different phase.

Your genset is set to deliver only 120V power and has only one hot wire. So it can be connected to both panels with the parallel switch. If you plug in one shore cord you can also power both panels using the parallel switch. But if two cords are plugged in the panels can not be connected via the parallel switch without combining two 120v wires hot wires that can be different phase.

So your system doesn’t have gremlins.

[sailorboy1]

Originally Posted by JebLostInSpace

Thanks for the reply!

1 - I can successfully use the parallel breaker to run the air con while bus A is energized. I know from previous experience that I can't run the microwave and air con at the same time this way, but that's okay.

2 - I'm not quite following you on this one. Sorry, I'm quite a newbie on electrical work. The breakers in the stern locker are the ones that should trip if there's current between common and ground? no those are nothing but overcurrent type breakers, but they should trip on a current problem before the the panel breaker. This doesn't always seem to happen, but normally does.Or did you mean the panel breakers should trip in that situation? The panel breakers trip every time I try to energize both sides. does BOTH the SP A and B breakers trip? The circuit A breaker in the stern locker also trips sometimes, but not every time.

3 - I have tried switching which line is plugged into which port on the boat. This produces no change in the behavior. so not a SP problem or the boat sockets because it doesn't follow the plugs

4 - I'm not following you on this one either. Are we talking about the breakers in the stern locker or the breakers on the panel? I'm also reading "shut" as being in the "on" position yes, I refer to a shut breaker as an on breaker, but I'm not sure if that's what you meant. But I can have Bus A powered on through SP, or Bus B powered on through SP. But if either A or B is on, then turning the other side on causes the breakers to trip. If I shut one side off, then turn the other side on, there is no problem. so if A or B is on with the other off then it doesn't trip and the polarity light doesn't come on?

Have you tried a different 50/30 amp splitter?

Do you have a Freedom 2000 charger/inverter? Is the remote on and what position is the inverter selector switch in?

[JebLostInSpace]

does BOTH the SP A and B breakers trip? - I believe the breaker on side A always tripped, and the side B only sometimes. However, I went to reproduce the issue and check, and suddenly everything seems to be working as expected. That's lovely, but I still feel like there is a gremlin lurking that will bite me in the butt later...

so if A or B is on with the other off then it doesn't trip and the polarity light doesn't come on - That's correct. When using only one side of the panel at a time, the breakers stayed closed, the polarity lights stayed off, and everything worked as expected.

Originally Posted by sailorboy1

Have you tried a different 50/30 amp splitter? - I have not. If the problems return, I'll ask the marina if they have one they can lend me to try.

Do you have a Freedom 2000 charger/inverter? Is the remote on and what position is the inverter selector switch in?

- No, I have a ProMarine ProNautic 12-40 that I installed about a year and a half ago after the original failed. It is a charger only, not an inverter. It is wired downstream of the main side A breaker, and that breaker was tripping before I turned on the charger. I also have a Xantrax 1000W inverter that is wired straight to the house bank. The inverter does not pass through the electrical panel at all from what I can tell, and has continued to work normally through all of the previous issues.