New Cord, Same Issue

Tod Johnson

New Member
Aug 11, 2020
4
Boat Info
2011 Sundancer 260
Engines
Mercruiser
My boat mechanic says he plugs my boat in to shore power and it works like a champ; with his cord. I try my old cord, and my brand new cord and the second I plug the boat in the main fuse breaker in back of the boat trips. I've tried multiple power posts as well. Do I need to replace that main breaker switch? I'm at a loss? I've got a Sea Ray Sundancer 260 for those scoring at home. THX Tod
 
Your main breaker is at the stern of the boat with the power inlet socket correct?
Your 2011 should be new enough that the boat main breaker contains an RCD right? (hint the breaker has several LED and "Test" / "Reset" buttons)
Have you EVER dropped the end of the "new" cord in the water? And how new is "new"?
Photos are always appreciated.

No I wouldn't buy his cord just yet...
 
Do you have multiple accessory items "on" while you're plugging in? Try turning everything off, including the breaker at the transom and the breaker in the MDP. Then plug in, turn the transom breaker on then the MDP breaker, then your accessories. How does that work? Also, FYI, best practice is to plug in the boat side first, then at the power post.
 
You say cord, exactly what kind of "cord" is this? Is it a standard 30A marine power cord meant for a boat that plugs into a stanchion without an adapter? I don't know too many mechanics that carry a shore power cord around.

If your at a dock and plugging your boat in to a stanchion, is this one that you have always used? A little more detail would really help us help you.
 
Thanks everyone for the responses. I'll get some pictures asap. The cord is brand new and has not gotten wet. 30 Amp, 50 foot cord from West Marine. Everything is off when I plug the boat into shore power. The RCD shows a ground fault indication (red light flashing), the reset and test button don't really do anything when i press or hold them in. The sequence above has been done a few times, but no matter the order, when I flip the breaker switch at the transom, it immediately trips.. I'll also ask my mechanic what he used to test this out. More to come!
 
Ask your mechanic if you can borrow his cord long enough to test it out on your pedestal. That should remove all doubt.
 
Thanks everyone for the responses. I'll get some pictures asap. The cord is brand new and has not gotten wet. 30 Amp, 50 foot cord from West Marine. Everything is off when I plug the boat into shore power. The RCD shows a ground fault indication (red light flashing), the reset and test button don't really do anything when i press or hold them in. The sequence above has been done a few times, but no matter the order, when I flip the breaker switch at the transom, it immediately trips.. I'll also ask my mechanic what he used to test this out. More to come!

This is why I would NOT trust that his cord is "right" and yours are "wrong".
BOTH your cords behave the same way, his cord is the outlier.
If you see his cord look at it carefully to see if he rewired it (swapping neutral and ground either on purpose or by accident)
If you have a multi meter check his cord for correct continuity the ground pin has the tab, check each pin to same pin on other end.
The G and the W should NOT be reversed (crossed at one end)

upload_2021-5-17_9-6-18.png


The RCD is doing its job. It senses something is wrong in wiring to shore.
With the Main breaker off the boat is only connected to shore by the ground wire, Neutral and Hot are open.
http://assets.bluesea.com/files/resources/technical_briefs/Technical_Brief_AC_Ground_Faults.pdf
 
I'm with Patrick. You have 2 cords, and your boat is telling you something is wrong. I'd be leery of the mechanics cord until I could do some more testing.
 
Could be a problem with all the pedestals at and around your boat...maybe the whole dock served by the same electrical branch (bad main ground or bad neutral). Is your mechanic plugging-in at a different dock, like maybe a service dock? If so, you could try your cords on that dock.
 
So to me the dock is wired with/for ground fault beakers. That means unless your boat has an isolation transformer in it, it is not going to work. An isolation transform removes the docks ground and only passes the ac without the green ground wire. The black/red (220v)/white wires are what is only needed when an isolation transformer is needed. The isolation transformer creates it's own ground through the bonding system and uses the dock ground to maintain the ground loop safely. Removing the ground can cause a very big electrical shock hazard if someone falls into the water. The ground wire is what the isolation transformer is isolating, but is still used.

Here is the ABYC standard. Also please don't just lift the ground from the stanchion, that can be a very big hazard if someone falls in the water.
 
So to me the dock is wired with/for ground fault beakers. That means unless your boat has an isolation transformer in it, it is not going to work. An isolation transform removes the docks ground and only passes the ac without the green ground wire. The black/red (220v)/white wires are what is only needed when an isolation transformer is needed. The isolation transformer creates it's own ground through the bonding system and uses the dock ground to maintain the ground loop safely. Removing the ground can cause a very big electrical shock hazard if someone falls into the water. The ground wire is what the isolation transformer is isolating, but is still used.

Here is the ABYC standard. Also please don't just lift the ground from the stanchion, that can be a very big hazard if someone falls in the water.

While an isolation transformer provides complete separation form shore side power the cost, weight and on a 260 the space to install would be problematic.
Few smaller boats have transformers and even with the new dock side grounding regulations they still work fine.

On new docks what usually happens is when the boat main breaker is turned on they trip the pedestal GFI, This is just showing that somewhere on the boat is a ground fault that wasn't known about until the marina upgraded the docks.

In this case the on board RCD is tripping before he can even engage the boat power not the pedestal breaker.

I upgraded my '94 300 to full RCD and 50A 240V with a full 60A galvanic isolation and have had no great problems.
I did upgraded the water heater and the stove top to 240V at the same time so the large items are all new.
https://www.facebook.com/media/set/?set=a.10216804598211841
 
... In this case the on board RCD is tripping before he can even engage the boat power not the pedestal breaker. ...

Yep, my bad, I answered as if the dock was tripping. Missed the RCD is flashing ground fault.
 
While an isolation transformer provides complete separation form shore side power the cost, weight and on a 260 the space to install would be problematic.
Few smaller boats have transformers and even with the new dock side grounding regulations they still work fine.

On new docks what usually happens is when the boat main breaker is turned on they trip the pedestal GFI, This is just showing that somewhere on the boat is a ground fault that wasn't known about until the marina upgraded the docks.

In this case the on board RCD is tripping before he can even engage the boat power not the pedestal breaker.

I upgraded my '94 300 to full RCD and 50A 240V with a full 60A galvanic isolation and have had no great problems.
I did upgraded the water heater and the stove top to 240V at the same time so the large items are all new.
https://www.facebook.com/media/set/?set=a.10216804598211841
Did you install a split phase generator? Or just not use the stove and WH when away from shore power....
 
The breaker was a future plan, boat never had a generator. So yes I was planning a 240v Split generator.
But after pricing new, used, etc. I am not going with an AC generator. I'll have to re-lablel that "Inverter". Next big project is going to be 240V Split Phase 48VDC Inverter/Charger, LifePo4 battery bank, MPPT controller w/ 48V PMA main engine drive.

I should point out the whole rig is RV Park friendly too. Power adapter, zero discharge (gray water tank), pump out system, even the AC will be able to run on land.
 
Thanks everyone for the responses. I'll get some pictures asap. The cord is brand new and has not gotten wet. 30 Amp, 50 foot cord from West Marine. Everything is off when I plug the boat into shore power. The RCD shows a ground fault indication (red light flashing), the reset and test button don't really do anything when i press or hold them in. The sequence above has been done a few times, but no matter the order, when I flip the breaker switch at the transom, it immediately trips.. I'll also ask my mechanic what he used to test this out. More to come!

your main breaker can only monitor what is downstream of the breaker.....not upstream. So, you can rule out the cord.

If the problem was with your cord it would trip the gfi breaker in the dock pedestal.

When did the problem start? Has it ever worked?
 

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