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Paddy_SP

TIG Welder Throws The Trip...

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Whenever I turn my 240V single-phase Hitachi Inverter TIG welder on, it throws the MCB trip - a 'B16'. I then have to navigate my way through a crowded workshop in the dark and climb up the ladder that is permanently in place for this job and reset it. Sometimes, everything comes back to life, but usually I also have to go halfway down the yard and reset the trip there too. Every now and then, I have to do both, then go through the house and throw the trip on the main fuseboard as well. Needless to say, this all drives me up the wall...

Once it's all reset though, the welder works perfectly until the next time I need to turn it on, whereupon I have to go through all the above farce once more.

My sparky mate told me that the solar panels on the garage roof were probably causing the fault, but I unplugged them and it made no difference. Reading another thread in this section just now, however, I saw that there are different kinds of breakers, which I didn't know. Apparently, a 'Type F' is less sensitive for certain applications - my question therefore, is whether this is likely to be what I need to save my sanity...? As ever, any help would be most appreciated!

Edited by Paddy_SP

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Having the same issues with an inverter drive for milling machine should be fitting a different mcb shortly that will hopefully sort things out I will let you know

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Thanks - I'm currently reading up on Type C and Type D breakers, as I know nothing about them - they seem to be better suited to welders though. It only ever happens on start-up, so I'm assuming it's the initial draw that is causing the issue. Hopefully, someone who knows about these things will come to my/our rescue!

Edited by Paddy_SP

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I've now edited my earlier posts to read 'MCB' instead of 'RCD'...

Edited by Paddy_SP

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I have type C MCBs in my workshop for the compressor and the welder circuits (32A and 16A respectively). Seems to work well enough, certainly never had any nuisance trips anyway. Lights do dim a bit when the compressor kicks in though!

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B curve are generally domestic type, C & D cater for a greater current in-rush on start up for motors, inverters, transformers etc, D taking the highest, the downside is they have a lower maximum earth loop impedance value (Zs) to meet the  disconnection time within the  requirements of the  Regulations unless they are RCD/RCBO protected which is 1667 Ohms  for a 30mA

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Type C or D have higher short term peak tolerance, less sensitive to surges, usually used for motors. 

C = min trip current is 5-10x the rated current

D = 10-20x the rated current

So check the cable to the welder can handle 80-160A  (16A C type) for a short period. Or derate the breaker a little.

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So if I read this right you have a consumer unit in the garage and one in the house. 

The tig trips the 16 amp in the garage and also sometimes a breaker in the house? Either the individual one feeding your garage consumer unit or the leakage trip?

Ideally I would put the lights on a separate 6 amp circuit. That way they will stay on if you trip the 16 amp in the garage. If your going to swap the 16 amp b type to a c or d I would leave the other sockets on the b type and have just a socket for the tig on the c / d type. You might want to use a 16 amp plug. That way any handheld tools or whatever that you might plug into the other sockets would still have the more sensitive trip. Obviously this might mean a new consumer unit so it might get costly. Outbuilding electrics fall under part p regulations too I believe. :unsure:

For the house if it's tripping due to over current then you can only go to a bigger trip if your wiring to the garage will stand it, but you could probably go slower there too. If it's the leakage that's tripping then if your garage consumer unit has a leaking in it you can move the garage supply to the unprotected side of the board. 

If any of that makes any sense whatsoever :unsure:

Have you tried the tig in one of the house sockets or someone elses garage just to make sure it's not faulty?

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Thanks for the helpful comments - you are almost right as to my set-up - I have a domestic board which feeds another that lives in a workshop unit halfway up the yard, and then that in turn feeds my garage where the TIG lives.

The TIG itself is on a 16 amp blue socket, which means that I can't plug it into most domestic supplies. My sparky mate tested it, and seemed satisfied that it was OK though.

Your suggestion that I put the lights on a different trip is a good one, however, half the time the whole supply goes because one or both of the other trips has thrown as well!

Likewise, I like the idea of putting the 13 amp sockets on a fast-blow trip. 

Lots to think about - I suspect that I'll keep the B16 MCB supplying the other sockets, and use the C16 to feed just the 16 amp circuit.

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I had the same setup on my last place: 32A in the house board fed armoured down to a smaller board in the workshop. To stop the house breaker going if I did something silly in the workshop, I put a C type in the house, with B's on the workshop. Saved a few trips indoors when a stone cold compressor stalled or the spot welder got cranked up to 11.

Edited by lo-fi

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That's interesting to hear - I'm wondering if putting a C Type in the garage will be enough - I may well have to go and do the same on the other two boards as well.

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Something else to consider is what gauge wire have you run down the garden? Too big a voltage drop tends to send trips a trippin'

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True - but in this case it's armoured split concentric of the same gauge as the supply to the house!

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3 hours ago, lo-fi said:

Something else to consider is what gauge wire have you run down the garden? Too big a voltage drop tends to send trips a trippin'

No not correct. If you are talking thermal-magnetic over-current, then voltage drop will have no effect.

If you mean RCD the also voltage drop has no effect, but on a long run possibly with moisture you may start to get a higher leakage current, which could cause a trip

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14 hours ago, Paddy_SP said:

That's interesting to hear - I'm wondering if putting a C Type in the garage will be enough - I may well have to go and do the same on the other two boards as well.

Best to do as lo-fi suggests, put a C even a D in the house (check cable run is sufficient gauge) and a B or a C in the garage, the it should never trip in the house.

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You could try putting a very long extension and running it off that, the resistance may be enough to reduce the initial surge :)

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So I have a B40Amp in the main fuse board, then in the garage 16A commando plug wired as a ring main to a B32Amp and a B6Amp for lights.
These never trip when the 2.2Kw compressor kicks in.

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Well - my C16 MCB arrived about 15 minutes ago - I fitted it and, Hey Presto - my TIG fired straight up without any faffing about, for the first time since I bought it about 10 years ago - woohoo!

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That's good to hear. Is it not tripping the house ones now either? 

Have you tried another b16, maybe that was faulty? I'm not sure I can understand why it was tripping the house ones as they are a higher rating unless the sudden unload somehow upset them? 

Earthing sometimes causes us problems at work and wierd things start happening but it gets a bit beyond my knowledge. We had some cooling pumps that used to trip and we had to re earth them to a different point to fix it. 

Are the grounded to the house or locally? 

Either way it's working :)

Edited by Cynic-al

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I've not tried the system in anger yet - but it did turn on without tripping anything when I tested it.

I suspect that the serial tripping was caused, as you suggested, by the sudden 'jolt', and that cascaded down the line - I don't think there was anything wrong. with the B16 MCB.

As far as I'm aware, everything is earthed throughout on the same circuit.

You are quite right though - the key point is that it seems to be working! :)

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Exactly the same problem happens when my compressor kicks in, 

 

Que standing on the bandsaw bed, on one leg leaning over with a broom handle to reach up and flick the trip back on.. Usually missing the correct trip and knocking the rest of them off, having to reprogram the radio etc.... 🙈

 

I need a C or D type trip for that too!

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