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All DC Breakers tripping


Jaston10078

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Hi everyone... Long time reader but this is my first post. 

 

We have a Mastervolt dc circuit breaker/distribution panel that has developed a curious habit. Recently all of the breakers have been tripping all at once without any obvious cause seemingly at random. 

 

This is our 3rd boat and the 1st with breakers rather than fuses so perhaps I'm missing something. 

 

I've been racking my brain..... I've recently installed a Waeco compressor coolbox as well as a Mastervolt battery monitor with double shunt. Installed new horns, a tunnel light on/off indicator lamp, I also wired a toggle switch in line to the fresh water pump. Many months ago I installed a 12v audio amplifier (draws 2 amps max) taking a feed from the water pump cables. 

 

Any thoughts would be greatly appreciated. 

 

Many thanks. 

 

James 

 

 

 

 

 

 

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6 hours ago, Kudzucraft said:

That is a strange. My first thoughts would be there is a problem in/with the breaker panel. The odds of all your DC powered items shorting at one time is about 0.  So I would start with the panel. 

I agree but I can't see all the breakers failing at once so I have no idea how that symptom could be produced. I sounds as if the protected side/appliance side of all the breakers has been shorted to negative but how that can happen I have no idea.

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23 minutes ago, WotEver said:

I think we need a photo of the back of the panel. 

Yes, I wonder if for some reason it has a master breaker that is tripping rather than all the individual ones.

 

Edited to add - maybe me but I cant see and such panels on the Mastervolt site.

Edited by Tony Brooks
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12 minutes ago, DandV said:

A rogue AC DC cross connection? 

 

I can't see how that would trip the all DC breakers but would probably trip something on the AC side.

 

If its an AC RCD that's tripping and the batteries are completely shot then the loss of a mains battery charger output may make it looks as if all the DC breakers have tripped. But they would not have popped out or flicked off.

 

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24 minutes ago, Tony Brooks said:

Edited to add - maybe me but I cant see and such panels on the Mastervolt site.

Google turns up a few hits for 'Mastervolt Circuit Breaker' but if you follow the links to the Mastervolt site you get a message that "This page doesn't exist (anymore)".  So I'm guessing it's a discontinued product.

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Just now, WotEver said:

Google turns up a few hits for 'Mastervolt Circuit Breaker' but if you follow the links to the Mastervolt site you get a message that "This page doesn't exist (anymore)".  So I'm guessing it's a discontinued product.

I got the same on some of the hits turn out to be for other makers products.

 

Looks like we need to wait for front and back photos from the OP because we can't look it up.

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1 minute ago, Tony Brooks said:

I can't see how that would trip the all DC breakers...

I can't see how anything could, other than a gross wiring fault, but I can't imagine such a fault. We need pictures.

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Just now, Martin Nicholas said:

My guess would be an over voltage on the supply side - a broken battery charger perhaps?

 

How would that trip  the breaker on a DC circuit  where the appliances were all turned off? If 240V  AC got onto the supply to the panel then I agree circuit that has the appliances turned on may trip. I know from experience that nominally 12V DC rated PVC insulated cables seem to cope with mains voltage without excess leakage.

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3 minutes ago, Martin Nicholas said:

My guess would be an over voltage on the supply side - a broken battery charger perhaps?

Tripping everything? Without damaging anything fed by the 12V?  Unlikely in the extreme, I'd have thought.

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Hi all, thanks for your thoughts. I'm grateful for your time. The boat does have AC from the Inverter, a mastervolt Dakar combi Inverter/charger. We do use the charger with our generator but the issue doesn't occur during charging. My gut feeling is something to do with the fridge or the Inverter... But I'm no electrician. FYI the Inverter and breaker panel are original from 2003

 

Pictures of breaker

 

Edited by Jaston10078
Link didn't work
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1 minute ago, Tony Brooks said:

I know from experience that nominally 12V DC rated PVC insulated cables seem to cope with mains voltage without excess leakage.

The insulation specification for automotive wiring (say BS6862) and domestic AC wiring is identical with 'smaller' CSA's (say up to 2.5mm) both being 0.6mm thickness.

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5 minutes ago, Jaston10078 said:

My gut feeling is something to do with the fridge or the Inverter...

Neither of which could trip all of the breakers unless their outputs are all connected together. 
 

Photos please. 

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24 minutes ago, Tony Brooks said:

 

I can't see how that would trip the all DC breakers but would probably trip something on the AC side.

 

If its an AC RCD that's tripping and the batteries are completely shot then the loss of a mains battery charger output may make it looks as if all the DC breakers have tripped. But they would not have popped out or flicked off.

 

Presumably the DC system is -ve earth. What would happen if an AC neutral was connected to a DC +ve?

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2 minutes ago, DandV said:

Presumably the DC system is -ve earth. What would happen if an AC neutral was connected to a DC +ve?

It would probably pop the breaker feeding the circuit that was so connected. It wouldn’t pop them all

5 minutes ago, Jaston10078 said:

I've edited the link to the pictures a couple of posts up... Thanks once again ?

Thanks peterF

Those disconnected ‘led indicator’ cables. Do they have 12V on them?

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WotEver... I'll check and let you know 

6 minutes ago, WotEver said:

Those disconnected ‘led indicator’ cables. Do they have 12V on them?

Multimeter says no... They deliver 12v to the indicators 

Edited by Jaston10078
Multimeter
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10 minutes ago, WotEver said:

It would probably pop the breaker feeding the circuit that was so connected. It wouldn’t pop them all

The led indicators feed from the load side of the breaker meaning each breaker with an led on the load side is active... Could this be a clue? 

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23 minutes ago, WotEver said:

It would probably pop the breaker feeding the circuit that was so connected. It wouldn’t pop them all

 

A neutral should be at earth potential, the same as a negative earthed DC system, but if a single neutral was connected to a DC12V  +ve then this neutral would be at earth plus 12v DC. Would this disrupt the AC feed? 

And what would 230V AC on  the 12V +ve  DC bus do to the 12V DC breakers?

I am just worried that any AC system on board has lost its earthing integrity and is earthing via the DC system.

 

Edited by DandV
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