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kevgermany avatar image
kevgermany asked

Welding Preparation

Steel boat, Pylontech US5000 bank, Cerbo, Easysolar II GX 5K, Orion. Common earth point to hull.

Welding will be MIG or stick on hull.

Boat is on the hard.

Shore power available if needed, but would prefer to use the on board supply.

Do I need to disconnect anything?

Multiplus-IIcerbo gxorion dc-dc
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3 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

If you are welding on the hull, and the welder ground/negative is connected to the hull, then the only preparation I would make is to disconnect shore power during welding. Reason: Every thing else is inside the Faraday cage formed by the hull. you can turn off all navigation equipment etc (if not already), as these are not needed on the hard. As point of practice, you should not be using the hull for negative power return on internal equipment, as this will increase hull internal corrosion.

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Al avatar image Al commented ·
If there's an isolation transformer for the shore power inlet, and the boat system has it's own RCD /GFCI then it shouldn't be necessary to disconnect shore, unless there's a question on the rest of the electrical installation. Although no harm in disconnecting shore supply, especially if welding could trip it, and the 5k isn't pushed too hard for too long. I found our old 3k Multi was fine for welding short periods / lower power. But a 5k is normally fine.
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kevgermany avatar image kevgermany ♦♦ commented ·
Not on shore power ATM, still enough solar. Won't be using the hull as a conductor, but thanks for the hint.
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Al avatar image
Al answered ·

@kevgermany I'm not a ticketed welder or ticketed electrician, but I've welded quite a few times on boats including my own, on the hard, and in water, without disconnecting anything, and without any issues. Initially (18 years ago) I did Isolate the main DC breaker, but I saw few others bothered, and seemingly nothing untoward has happened. Unless someone else chimes in with a serious safety concern, then I'd just get on with the welding!

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kevgermany avatar image kevgermany ♦♦ commented ·
Experience. Always better than theory.
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kevgermany avatar image
kevgermany answered ·

Quick update. No isolation transformer installed, just a galvanic one., didn't connect shore power, ran the welder direct, worked flawlessly on 80A.

Thanks to both.

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