ive got an oil cooled oxford arc welder,sometimes when i switch it on it trips the circuit breaker even the the rod isnt in contact with the work piece,when it finally gets going it will trip the cb after a few mins,its 1ph and running through a 30 amp supply,any ideas?

Depends could be a few things.
A weak or weakend breaker
Are you using a B C or D rated breaker??

dunno what type of breakers they are,its funny it should trip out before i strike up,makes turning 2 tons of rebar into something useful a bit tedious

Both my Oxford and my 110v transformer will sometimes trip out on switching on, I put it down to high initial currents while the coils energize, but the one on the Oxford has never blown once the power is on. 30A should just about power a 4mm mild rod on single phase (only just mind) if it's tripping out with a 3.2 then I'd suggest trying a new breaker.


Edited to add, mine might be on a 40A trip, can't remember how I wired it up, used 5mm cables though from the consumer unit though.

[Edited on 4/9/07 by gazza285]

It'll say what type of breaker on the front beside the amperage etc.
I'd say go for a D rated (motor rated for high start up currents) but be very aware that the fault load current and time to trip are vastly increased by doing this and as such so is your personal safety.

I don't mean to sound cheeky but have checked either with a multi meter or a megger to see whether you have any continuity earth.

Sorry if I'm teaching granny to suck eggs just wouldn't like anybody to get hurt.

Regards Davie

cheers for the replies peeps,ill get a new cb sorted and check the earth

John i've got a megger here if you need one