Electrical Disconnection when welding??

[dignity]

I need to do a bit of welding on my boat, I'm a bit unsure whether or not I need to disconnect everying electrical i.e. starter-motor / alternator, is it a case of just taking the earth connection off, or should they be totally removed to avoid damage when welding.

Also the shore-power isn't good enough to run my welder, can anyone forsee a problem if I use my onboard generator (which is totally isolated from my hull)?

Any thoughts would be gratefully received before I fry my electrics!

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[oldharry]

Arc welding can induce voltage spikes in adjacent wiring - the same effect as the crackle on the radio when there is lightning about. This has been enough occasionally to damage alternator diodes, and other voltage sensitive equipment druing arc welding, so good practice recommends disconnecting alternators and electronics from their wiring first. No need to remove them altogether - just ensure they are isolated from any cable runs which could pick up induction currents. Starter motors etc do not have chips or diodes in them so are safe enough, and most good quality electronics have surge protection built in anyway.

Simply a case of better safe than sorry!

Using the generator should not be a problem, providing you earth it properly to shore first. Otherwise the metal you are welding could be at a potentially dangerous voltage relative to anything that is actually earthed - like the water round the boat! Again - safety first!

Check the makers recommendations for the genny and the welder, and follow them.

If you are then still not absolutely sure about the safety of your specific set up for this application - ask a marine electrical expert to check and advise you for your specific installation - it should only take minutes and you do need to be certain you are not setting yourself up for a nasty accident!

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[tynesman]

You must ensure that the earth wire from the welding set has a good earth connection and all other onboard electrics are switched off,or you will heat/melt the onboard electrical cables.
Also take care not to weld next to any cables or cover them,if you are using a metallic arc welding set even the electrode sparks could burn cables.
I trust you are welding well away from any petrol!
Good luck

Happy sailing
Tynesman

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[wpsalm]

also....important to make sure the ground connection is as close to the work as possible to help minimize changes to the vessel.s magnetic field ,in order to avoid the trouble and expense of compass adjusting....

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[DavidP]

Hi

Sound advice from the rest of the people on here , but i would also disconect the battery or batteries as well.

Dave.

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