Shore Power Wires Melted Today Yikes! Please Help Solve What Happened!

[jrmartin505]

Good day,

I’m a complete beginner with electrical so please bear with me

So I was using my Wesco WS3434 radial saw today to make a battery box for my new LifePO4 battery and Victron MPPT (mounted to outside) and when I went back in the boat I found my shore power had gone out. I used my voltmeter to track shore power current to a junction box where power was going in but not coming out. When I opened the box I found several wires and wire attachments all melted into balls of plastic goo and a strong melted plastic smell (Image01-02).

So I looked up my saw and found it is 1400 watts (Image03).

And I looked up the Mass GI Transformer Isolater (Image05-06) to see the installation instructions and specs. Mine is the version 3.5, in column 1.

There are two separate sets of wires in the box. The grey wires- shore power in to Mass GI Transformer in connected together, and separately 4 black wires connected together.

What struck me right away was that the worst melted wires (grey ones) were from the shore power in to the Mass GI in, which were completely charred and melted, leaving one wire unattached as the white plastic connector had completely gone to black goo.

Also I noticed the yellow wire with the green stripe which is ground in (image06), was not connected at all, both ends snipped and just left there disconnected. Also, there is no GFCI or fuse that the (image06) instructions called for.

Next I noticed the black wires which come out from the Mass GI to the junction box and split to a couple electric outlet wires and a power inlet to the battery charger were also melted.

However on this end the ground wires are connected, but again, no GFCI as called for in instructions, and no fuse.

I don’t know how long the boat has been like this, but I’ve used shore power almost daily for a couple years since I bought it, and run more powerful devices like a 2400 watt water kettle with no problems until now.

Any Idea what went wrong???
Scary because I read the number one cause of death on boats is actually fires. And I’m staying on the boat now, so double scary.

I’ve always wondered about grounding on a boat, as someone I was told was a very reputable boat mechanic said never connect a ground to say a metal plate on the hull, which makes contact with the outside (water) as some kind of electrical corrosion can cause huge damage to your prop, prop shaft, and engine. So I’ve always wondered what people do with ground wires on boats. Now I NEED to know.

Any shared wisdom greatly appreciated!

[Multiboxer]

Those white blocks are not supposed to be used for higher amperages.
Use them for low power light fixtures maybe but nothing else.
Instead you should use terminal blocks that you can mount on DIN rail that are rated for the amps that you expect to draw.
Another option is wire blocks of the brand WAGO which will fit more easily.
I strongly suggest getting rid of all those low quality blocks you have.
Strip the flexible wire, press a wire ferrule over them and clamp them in a WAGO block.

The vast majority of fires with electrical systems are due to bad electrical connections like yours.

[jrmartin505]

Ahh, OK, so the cheap connectors are the problem. Good to know!
So to get this done I need 1 wago for each color of wire right? So 4 black wires with 3 wires in each means I need 3 wagos, each 4 wide?

And then for the 2 grey wires I need 2 wagos each 2 wide? Assuming I leave the ground disconnected on this end as it is. Would you happen to know about grounding on a boat, and if this is the correct way?

If so then I need 5 wagos if I understand this right. And maybe also a wider junction box to fit them, depending on size.

[Auguste1927 (Elektrik)]

As you said,
You are completely beginner with electricity.
You have to be happy, that you dont lost your boat by fire, or died by electric current.

But you are working in a good direction, bc you noticed, that the yellow/green cable is not connected.
The yellow /green cable is very inportant, if it is wired correctly, it might prevent people dying on your boat by electrical shock. Makes sense??

Attached is a picture how such an installation should look like:
(as you might noticed, the yellow green cable is somehow connected… ;-))

And a strong advice: You need professional help!. YES!

Do whatever you want, but for connecting such a fixture you need an certified electrician!

Good look, remember my words.
Rno

[jrmartin505]

I am getting professional advice
And I’m not a complete beginner, however I have a healthy dose of fear over electricity + boats, and I have learned enough to know that the guy who owned this boat before me, definitely did not share my same level of caution. Amazingly he sailed the boat for over 30 years, and sailed around England! And I have already found several electrical faults, IE the topsides electric was all wired wrong and the ‘steaming’ setting was turning on anchor lights, and vice-verse LOL

Anyway, I will likely get a pro to come check some of this stuff out at some point. For now I will take your feedback that the ground should be connected, and see why those wires are not. It’s possible he never connected the ground wire in the Mass GI as well. Also, since grounds are connected on the black wires, I will trace the grounds from the batteries and chargers to see if I can find a universal ground on the hull of the boat.

Either way, I will also follow Multiboxer’s advice and seek out any of those bogus connectors (there is another power outlet on the boat) and replace them with WAGOs as he suggested.

Thanks for the feedback! I’ll keep posted on progress

[anon39974850]

My immediate comment to your original post, would be that the connectors show signs of corrosion (which doesn’t help with conductivity). This MAY be the cause of your issue.
It could be a short elsewhere, that lead to the corrosion damage manifesting itself.

The corrosion looks as if it has occurred over sometime.

The main initial taking away is: How did water/moisture enter the enclosure in the first place.

Great to hear you are getting professional assistance.

Please do feel free to feed back the casual outcome. Others will find it interesting / informative / useful / education.

[jrmartin505]

Well moisture on the boat has been the single most difficult problem to solve as a live aboard, especially in winter. The mildew fungus is a constant problem, though I put more insulation every year, and have gotten a powerful house dehumidifier, which kept the humidity so low that I was getting dandruff all over my skin was drying out so bad. Yet still, the mildew persisted…

Anyway, yeah, moisture all over has been a constant problem

Also the jb box seems like it has something resembling an attempt at gaskets over each wire entry, but they are all loose, and one is missing entirely. Maybe the box should be sealed up in those areas with silicone or duct tape to prevent the winter moisture from getting in.

As far as professional advice, I was half joking, you all are it! LOL
Well for now anyway…

[jrmartin505]

Also has anybody heard of a reason why the ground wire on the Transformer Isolator would (or should) NOT be connected?

Maybe this is something boating specific. Then again that device is made for boats.

[jrmartin505]

So I just tried one of those AI searches and got this:
“If the ground wire on your boat’s isolation transformer is not connected, it may be to prevent galvanic corrosion and ensure safety.”

And found these on youtube:

Prevent Galvanic Corrosion on Your Boat: Galvanic Isolators Vs. Isolation Transformers

Wiring Plan & Victron Isolation Transformer - Ep. 108

What Is the Difference Between a Galvanic Isolator and an Isolation Transformer?

OK, so more research to do…

[Cardy01]

The “ground” wire on the right hand side of the isolation transformer should go to the hull of the boat if steel or to the main ground terminal if polyester. If the ground wire is not connected then depending on what has been done with the neutral you may find that RCDs do not function. Under normal installation conditions if the boat is in the water then the shore earth should be isolated and the isolation transformer connected to the boat and the neutral bonded to that - sometimes this is done in the transformer. Your product sheet shows it done outside. You might want to ask this question on a Mastervolt forum …

[pwfarnell]

From pics a steel boat (UK narrowboat?), as said, ground the output earth to the hull.

Chasing the moisture is a pain, especially when air can get to cold steel surfaces, even if the air is dry at 21degC, by time it touches the steel surface it can still drop out condensation. Sealing the steel is the only real way which is why sprayfoam tends to be used for new builds.

Anyway, the reason for posting was what you need on the junction box is cable glands, they come with a proper rubber gasket and can be tightened up. Example linked but can be found almost anywhere.

RS PRO Grey Nylon Cable Gland, M12 Thread, 3mm min., 6.5mm max., IP68 | RS

[jrmartin505]

OK, so a quick update.

1. I got my new Wagos (Image 09). Special thanks to Multiboxer for the tip

2. I clipped and stripped a few pieces of both the black wire (post isolator) and grey wire (shore power in to isolator) and did indeed find signs of corrosion on the grey wires, even a few inches back from the melted terminals (image 14). The black wires however seem to be OK (image 15). Thanks to NeptuneUK for pointing this out! So I’m looking for some new wire for this line. It seems to be about 1.1mm which is 18AWG and I think I’ll go one size larger 14AWG for the replacement. Now to find quality wire…

3. So I found a very interesting boating thread talking about ground not connected to the Isolator and it’s quite the debate. I have to say I’m leaning toward the advice from Jedi’s second post, where he shares the following image and second’s Elektrik’s advice that the ground should definitely be connected from shore power to isolator. So I’ll connect this wire when I get new cable for the shore power end. Also he gives a tip “One test that MUST be done is make sure that shore ground is NOT connected to ships ground. Simply test with multimeter in continuity mode, then check with resistance mode to see that there exists a high isolation value.” OK, so I also have a multimeter now and I’ll figure out how to do this, and in doing so I’ll track down where my ship’s ground is located per advice here.

Shore Ground NOT Connected to Isolation Transformer - Cruisers & Sailing...

And here is an image Jedi shares of a ‘correct system’ (image 10).

[jrmartin505]

OK, I’ll check it tomorrow. I’ll track down the ground wires on the boat, and from the right side of the isolation transformer as you suggested. This is definitely something I need to find! I’ll keep posted on progress. Thanks:)

[jrmartin505]

It’s a polyester sailboat, just FYI
So yeah, moisture in that junction box might have been a real problem, especially from last winter. I’ll shop some cable glands as you suggest. Thanks!

[dmsims]

I hate those terminal blocks (in the original pics)

Screws(s) could work loose and…

Make sure you have strain relief for the new wiring

[EvSC]

Victron has a nice information leaflet “grounding (earthing) of boat electrical system explained)” You may want to study that thourougly.

Second advice: if you are a beginner in electrical stuff, don’t go for DIY lithium batteries.
Those are much more dangerous thant lead is if not properly connected, fused and charged with the right settings. You could even fry your alternator.

[EvSC]

The title is actually “Wiring unlimited”