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I think I would need to be there to work through this. Sorry, working remotely with just text email makes it difficult to understand where you disconnected the 24-volt negative cable in the forward locker. But, see the circled wires in this photo. Did you remove all of them from the post?
So I took off the negative cables from the master switch one by one and checked the Masse indicator. Fault turns out to be on the biggest cable which is 95mm square. This is the cable that runs to the bow locker plastic electric cupboard.
So great, I assumed that it must be the windlasses or the bowthruster. Trouble is that even if I disconnect the 95mm sq cable that goes into the cupboard and then check the indicator, the light comes on...
I can only assume the problem is between the bow locker and the battery locker, but from my investigations it is a straight run in a conduit with nothing T’d off it.
S/Y Amelia anchored Mikanos with the Meltemi cranking.
On 22 Jul 2020, at 20:29, CW Bill Rouse <brouse@...> wrote:
Good luck. Let me know how it goes. Sometimes the cause is evasive. I should have also said the most probable suspect after the macerator pumps is anything that you have added or changed AC or DC since the MASSE last reported no negative fault.
I have been playing around at trying to identify the leak to no avail. So the next step will be as you suggest. I will disconnect the battery positive cables and the remove all the negative cables from the big switch and reconnect one by one to identify the circuit at fault.
On 22 Jul 2020, at 17:46, CW Bill Rouse <brouse@...> wrote:
I did it by unbolting at least one of the main switches and pulling it aside.
You can also remove the positive wire from the battery bank to the switch by unbolting it at the junction block inside the battery compartment and also remove the positive wire on the starter battery. An alternative in the battery bank which may be easier is to remove the positive wire from the battery post each of your 6 pairs of batteries (the one to the junction block).
Alas it is not the Macerators. I hate working in the space for the main battery on/off as it is so easy to short out the positive to negative with a ratchet handle... maybe I can cover the positive with plastic sheet or something...
Stern to in Finikas Syros waiting for the Meltemi to ease just a tad...
On 22 Jul 2020, at 00:43, CW Bill Rouse <brouse@...> wrote:
Ofer & Nick,
Remember, the minus Masse Light means there is a connection between 24-volts negative to the Amel bonding system. The most common issue is a Jabsco Macerator pump that has developed a leak at the seal, causing a connection to the Amel Bonding. Start by disconnecting the green/yellow wire from each macerator pump. If the light no longer comes ON, you have found it. Replace that macerator pump and reconnect the green/yellow wires.
If it was not the macerator pump and the light is ON for the (-) side, it is more difficult because the individual 24-volt breakers only turn OFF the positive side (+). For a negative side (-) Masse fault, you will need to disconnect the negative wires from the negative main battery switch. On most Amels, this is the lower switch. When the light goes out, you have narrowed your search to one main circuit.
If the (+) side is ON, try turning OFF each breaker throughout the boat one at a time. Don't forget breakers
for the windlass, winches, and breakers in the engine room. Do this with all breakers.
On Tue, Jul 21, 2020 at 12:32 PM ofer magen <ofermagen@...
We had the same problem.
It took long time to solve , because the light was not always ON.
The way to find where a bad contact between the minus and the grounding system is, is to start from the main switches near the batteries, disconnect each of the cables while checking the light. Ones you find a cable that if disconnected the is OFF, look for the equipment down the cable and check the contacts and put corrosion x.
We found the problem in the forward locker . We had a leak of water from the new Bad! installed windlass rubber deck switches that created humidity on all electrical motors in the locker.
Good luck with the challenge.
You can call me if you want more info.
A 54 160 2010