Welding / Electrical question please??

[mikewilkes]

I have a steel cat in a marina on 220 volt shore power, also have a sterling 40 amp battery charger / power supply to keep batteries topped up and the beer cold in the fridge.
I wish to weld a plate over a hole in the bridge deck BUT do I need to
a) Disconnect the shore power
b) Turn off the battery charger or
c) Disconnect my batteries
or any other combination of ideas???

 

[compie1]

a) YES
b) YES
c) YES

 

[fireball]

I think that probably answers the question! /forums/images/graemlins/laugh.gif

 

[robind]

You may get away with it? but I wouldn`t chance it! also make sure that you have a good local earth. otherwise bearings ets may spark up etc.

 

[mikewilkes]

Thank you gang.
Knew I would get straight answer.

 

[crisjones]

Robind's point about the earth is very very important. If the earth between the welder and the material being welded is not A1 the welding current will try to find it's own way back to earth and can cause all sorts of nasty problems, such as melted / burning wiring harnesses as well as pitted bearings.

I would suggest wire brushing the earth clamp as well as making sure the earth point is clean of any paint, rust etc.

As said definitely disconnect batteries, alternators and shore power. Connect the welder direct to the shore power on the pontoon if using an electric welder, although this may not be rated at a sufficient current for welding, you will probably need to use an engine driven set for anything but very light work. A 10A shore power socket will probably trip at welding currents as low as 80 A.

 

[mikewilkes]

We are on a 32 amp shore power so hope that is enough.

 

[the_wanderer]

It may be a good idea to disconnect the alternator on the engine. Diodes in the unit are funny things and do not like stray currents. Don't forget to re-connect afterwards as they also dislike being run open circuit.

Regards.

Alan.

 

[ccscott49]

Disconnect both shore supply and batteries. Just in case, both terminals on the battery.

 

[essexboy]

I would also diconnect the alternator(s)

 

[Lakesailor]

I sometimes create the earth on the patch rather than the main body you are welding to. It has the chance of delivering a direct circuit rather than all the way round the houses. You just need to weld more like gas welding using the heat to flow the rod into the major piece. Works well on arc, but a bit more tricky with MIG.

 

[Superflid]

Would agree with connecting the earth clamp to the patch and not the main body. I've been in the habit of using a small tack weld to connect the earth clamp to the workpiece to ensure a good connection and lessen the chances of stray currents. Easily broken/ground off afterwards. Dunno if it's recommended practice, but it works for me!

 

[TheBoatman]

Mike
For pure safety reasons I'd be inclined to disconnect the wire from the altenator as well - bit belt and braces but for a few seconds worth of work could save you a few quid!!

Peter.

 

[evmars1]

so would I.

 

[cliff]

a) NO
b) NO
c) NO.

Nor is there any reason to disconnect the alternator lead. - popular myth that the alternator has to be disconnected.

Lets think this one htrough - ship at sea, underway, needs welding repair?. Offshore platform - lots of welding going on, do they shutdown all 240v supplies, motors, alternators etc?

As for a faulty welding earth causing the welding current to find an alternative path to earth - what a load of bølløx. the welding circuit has nothing to do with "earth" - if the welding return lead is faulty the welding current and/or voltage will be unstable. If the welding return lead is not connected and you strike the electrode against something earthed there is no current.

I would suggest you get some one to do the job who can actually weld and does know what they are doing rather than letting some over-enthusiastic amateur loose.
--------------------

"Artificial intelligence is no match for natural stupidity"

 

[Superflid]

[ QUOTE ]

some over-enthusiastic amateur......

[/ QUOTE ]

Got me! /forums/images/graemlins/grin.gif

Although I've always refused to work on anyone elses property.

 

[andy_wilson]

Having considered carefully the answers...

a) YES
b) NO
c) If you like
d) If there was a d), it would be a definite maybe!

 

[compie1]

Cliff,

Now you tell me why every man in the world who gets a welding cource (electrical) is kindly advised in capitals bold and as big as they can print it :

"UNPLUG or DISCONNECT ALL POWER SOURCES THAT ARE IN CONTACT WITH THE METAL YOU ARE WELDING"

Not for the fun of it, i think... talk to a body repair specialist, you'l see what he says...

Weld a piece on to your car without disconnecting the battery and you are about to see you meters and bulbs jumping out of their sockets...

 

[ccscott49]

I was taught when welding on vehicles to always disconnect the battery. But and it's a big but!! I see where Cliff is coming from, both Mike and myself work on offshore platforms/rigs (well he DID) and the stuff just keeps running, welding just goes on day in day out, maybe theres something else to consider with vehicles/boats, dunno, but better safe than sorry, eh? Disconnect!

 

[Superflid]

Friend at Boston has a 40'ish foot steel fishing boat with a welder built into the engine room, wouldn't imagine they disconnect everything to weld.....