Need help with 120 volt system in a 1992 440DA

[BoaterCanuck]

Hello,

I have a 1992 Sea Ray 440 DA. When I turn on the accessory breaker on the 120 volt side (white breakers) on the panel, both main breakers reset as well as the breaker on the dock. There is a GFCI attached to this part of the circuit (among other things but not sure what else). Even when the GFCI is completely removed and the wires for the GFCI are connected to nothing, both mains still trip when the Accessory breaker is turned on.

I am running 1 30 amp cable from the pedestal on the dock to a Y cable. The Y cable plugs into the boat at the port and starboard 120 volt inputs.

All works fine until the Accessory breaker on the 120 volt side is turned on.

Does anyone have a wiring diagram for this 1992 440DA or a similar boat?

Why would both mains trip? I was under the impression that the port side and starboard side are completely isolated.

Any help would be appreciated.

Thanks in advance.

 

[ttmott]

Hello,

I have a 1992 Sea Ray 440 DA. When I turn on the accessory breaker on the 120 volt side (white breakers) on the panel, both main breakers reset as well as the breaker on the dock. There is a GFCI attached to this part of the circuit (among other things but not sure what else). Even when the GFCI is completely removed and the wires for the GFCI are connected to nothing, both mains still trip when the Accessory breaker is turned on.

I am running 1 30 amp cable from the pedestal on the dock to a Y cable. The Y cable plugs into the boat at the port and starboard 120 volt inputs.

All works fine until the Accessory breaker on the 120 volt side is turned on.

Does anyone have a wiring diagram for this 1992 440DA or a similar boat?

Why would both mains trip? I was under the impression that the port side and starboard side are completely isolated.

Any help would be appreciated.

Thanks in advance.

It seems someone has tied the two hot legs together somewhere on the boat on the two 30 amp circuits. That is a direct short and will trip both sides. Most marinas have the 30 amp power receptacles on a pedestal out of phase. Your generator transfer switch does tie them together but it first disconnects the shorepower.

 

[BoaterCanuck]

It seems someone has tied the two hot legs together somewhere on the boat on the two 30 amp circuits. That is a direct short and will trip both sides. Most marinas have the 30 amp power receptacles on a pedestal out of phase. Your generator transfer switch does tie them together but it first disconnects the shorepower.

Hey ttmott,

Thanks for the reply. This boat is actually not mine. It belongs to a dock mate. I don't think that both mains inside the boat tripped. I will see him on Wednesday next week and see for myself. If it is not both mains then this is simply a short somewhere in the boat. Was fine last year. I suspect a varmint may have gotten into the boat and chewed some wires. I will reply when I find out what's what.

Thanks again!

 

[BoaterCanuck]

So to add to this mystery, this only happens when 2 x 30 amp cables are both plugged into the pedestal and each 30 amp cable is plugged into the boat.

When a Y cable is used, this does not happen. Only changes the owner has made is installed 2 CGFI receptacles.

Any help would be appreciated.

 

[Stee6043]

This may not be entirely useful but per the manual the 1992 440 did not come from the factory with an accessory breaker on the 110V panel.

Has the owner tried a different pedestal and different shore power cords? It would be ideal if he could eliminate those from the trouble shooting. After that I'd focus on that accessory circuit. Pop the breaker panel open and have a look behind it. Are the GFI's he replaced/added on the accessory circuit?

 

[hughespat57]

So to add to this mystery, this only happens when 2 x 30 amp cables are both plugged into the pedestal and each 30 amp cable is plugged into the boat.

When a Y cable is used, this does not happen. Only changes the owner has made is installed 2 CGFI receptacles.

Any help would be appreciated.

This makes perfect sense it it what @ttmott is saying.
When you use a single 30A and a Y you are tieing both panels to the same 120v leg of the shore power.
When you use two 30A cables each cable is most likely on a different 120v leg of the shore/commercial 240/208V circuits.
Marinas will almost always alternate each 30A receptacle down a dock between the Hot legs to balance the power draw.

In a single modern pedestal you will often have a 50A outlet which uses both 120v legs to provide either 120 or 240 to the vessel. The 30A receptacles will be one on each leg.

The way to trouble shoot is this.
1. turn off ALL AC breakers on the boat, mains and sub circuits.
2. connect the two 30A cords. Turn on the pedestal breakers for both 30A.
3. turn on both panel main 120v breakers. (it should not trip, you stated this before)
4. turn on ONLY the "Accessory" breaker. (if it trips the fault is most likely in the panel itself, the "Accessory" is touching or chafed on the other 120V bus bar or the other main breaker.) I suspect it will not trip.
5. Now go one by one down the other 120v panel (the one not having the "Accessory" breaker)

Turn each circuit on one at a time, does it trip? No? Then turn off and do the next breaker.
I am confident you will find only one breaker on that panel the causes the fault.

Now you have the two circuits identified that are cross connected or shorted to each other.
Again the most likely location is in the panel.

So if opening the panel be sure both cords are unplugged from the pedestal before opening.

 

[BoaterCanuck]

Thanks for the replies guys. I will try all of this and once I find a solution I will post it here for others.

Thanks again!