Recommended circuit for arc welder, CU - Garage - welder.

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Crow_Man

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Hi guys 'n gals.
In a nutshell what would you recommend from the consumer unit, 30m to a garage, CU in there and out to an old oil filled arc (stick) welder capable of going from 30 amps up to 180 amps.

At the moment I have CU in the house with 45amp Type C RCBO, 10mm T&E to garage 30m away, old CU with wired plugin fuse (yes, I know, that's crap) then at the moment running off a 13amp 3 pin plug. (again that is probably crap, probably needs a 32amp blue plug and socket?)

At the moment it is tripping the 45amp RCBO, not instantly but more like a delayed trip. I can weld for a few minutes at 100amps and it trips. Resets fine but will trip again after a minute WITHOUT me actually trying to weld anything else.
 
With a good unit looking at around 26 amp to run it, so in-rush may take out a MCB but once running it should have been OK, what you don't know is it earth leakage or over current taking the RCBO out. In the main we no longer use the old oil filled welder, there was a problem if dropped the wires could bend and short circuit, so an earth was essential, however that mean that if the welding earth made a poor connection you could burn out the workshop earths, so all earth wires had to be at least 25 mm² or a lot of damage could happen, also the oil was nasty stuff, with PCB's and I don't mean Terry Pratchett style particular crunchy bits. I don't think I have ever tried to run an oil filled welder through a RCD.

There is also a problem that they tend to put spikes on the line and dip the voltage which can cause complaints, so today near everyone uses welder inverters. This also likely will produce problems likely need a type F RCD and as far as I am aware type A is the best you can get with RCBO's that fit in domestic consumer units.

Basic thing is welding at home is not a good idea.
 
It's not so stupid. You are probably in contravention of your contract with the electricity provider if you haven't informed them of this, and they are entitled to cut you off if you cause any problems for others.
 
Also from https://www.ukpowernetworks.co.uk/i...an_electricity_connection_projects_online.pdf


upload_2020-7-28_21-22-36.png
 
Type F
Type F RCDs is a new RCD type recently introduced in IEC 62423 and in IEC60755. In addition to the detection characteristics of type A RCDs,type F RCDs are specially designed for circuit protection where single phase variable speed drivers could be used. In these circuits, the waveform of residual current could be a composite of multi-frequencies including motor frequency, convertor switching frequency and line frequency. For the reason of energy efficiency, the use of frequency converters in certain loads (washing machine, air conditioner, …) is increasing, and type F RCD will cover those new applications.

Type F also has enhanced disturbance withstand characteristics (non-tripping on surge current). They are capable of tripping even if a pure direct current of 10 mA is superimposed on a sinusoidal or pulsed DC differential current.
Click to expand...
I think you need a type F RCBO, but good look in finding one. As far as I am aware you can only get
Type AC and
Type A
For the single module width RCBO's used in most consumer units, even the type A is hard to get since often there is nothing in the adverts to say what type is fitted, my RCBO's stated type B on the box, but were type AC curve B. If it were mine I would temporary fit a 32A MCB and see if it trips, I say 32A being lower that the 45A as it will prove if it is the RCD part of the trip which is the problem. However if it proves to be the trip then how to get around the problem I don't know. There are three designed of RCBO the standard single width unit common in the consumer unit, the unit which attaches to the side of a MCB and the what looks like a current transformer with a button which can activate another trip normally used with mounded breakers and often adjustable which is not permitted when in the control of an ordinary person. In this
it shows one of the separate current transformer coils to the actual trip.

The problem is your using an industrial unit in the home as as said they were never designed for home use, what has happened is it costs a lot of money to get rid of the oil in the old welding sets, so they were near enough given away, today you need a licence to buy and handle equipment that used the old oil, I know it cost the Heritage railway a lot of money to get rid of their old equipment due to both old oil and asbestos.
 
Crow_Man said:
At the moment it is tripping the 45amp RCBO, not instantly but more like a delayed trip. I can weld for a few minutes at 100amps and it trips. Resets fine but will trip again after a minute WITHOUT me actually trying to weld anything else.
Click to expand...

Has the fuse in the plug ever blown? I regularly weld at 100A+ I have a 50A type C submains to the garage, and then a local 16A type C local circuit, and have never had issues. I’d imagine you’re running at similar currents on the primary. Perhaps you have an earth leakage issue which is causing your RCBO to trip, rather than overload current.
 
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