ChrisLeary
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| posted on 6/3/14 at 10:17 AM |
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Welder tripping MCB
Morning all,
I've recently moved house, and I now have a detatched garage at the bottom of the garden. It's a new build so there are already sockets
and lighting in the garage.
I got the welder out at the weekend and as soon as I pressed the trigger on the torch, the socket MCB tripped.
I have a SIP Migmate 150. The MCB is a Hager MTN116, B16. I've done some research, and this is apparently a B type MCB rated at 16A.
I've had a search around the forum, and on google, and what I've read seems to suggest I should have a C type fitted, but I'm still
not sure what Amp rating I can go for to 1. stop the MCB tripping, and 2. to be safe.
Can someone shed some light on this please? I really need to get some welding done on the car, otherwise there's no way it's going to be
on the road this summer!
Thanks,
Chris
Don't force it! Get a bigger hammer...
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FuryRebuild
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| posted on 6/3/14 at 10:48 AM |
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It's the class of breaker.
I have a 45A supply in my garage for mine, ran on a separate line from the main feed. It has a 'class c' breaker on it, innit. (It may be
a class B, but it's one of the two, both of which aren't the normal kind).
Anyway, the point is - it's a special kind of breaker that lets a surge through for a second or so to allow for motors, welders, etc. to let
their initial kick through before things settle down.
cheers
M
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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peter030371
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| posted on 6/3/14 at 11:03 AM |
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I assume the 16A is for the ring main feeding the garage sockets, is this in a consumer unit in the garage? Whilst type C would be better most garage
type consumer units would have a 32amp type B for the ring main and this would generally be fine for a 'domestic' sized welder.
I would go for a 32amp (B) and see if that solves the problem but also make sure the wiring from the socket to the consumer unit is up to the job.
The other issue could be voltage drop though, how long is the feed from the house and can you see what size/ type of cable it is.....if its long and
small cable you will always have issues trying to run a welder on the end of it 
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FuryRebuild
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| posted on 6/3/14 at 11:07 AM |
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This detailed post beats my ramblings any day 
quote:
Originally posted by peter030371
I assume the 16A is for the ring main feeding the garage sockets, is this in a consumer unit in the garage? Whilst type C would be better most garage
type consumer units would have a 32amp type B for the ring main and this would generally be fine for a 'domestic' sized welder.
I would go for a 32amp (B) and see if that solves the problem but also make sure the wiring from the socket to the consumer unit is up to the job.
The other issue could be voltage drop though, how long is the feed from the house and can you see what size/ type of cable it is.....if its long and
small cable you will always have issues trying to run a welder on the end of it
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
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ChrisLeary
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| posted on 6/3/14 at 11:33 AM |
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quote:
Originally posted by peter030371
I assume the 16A is for the ring main feeding the garage sockets, is this in a consumer unit in the garage? Whilst type C would be better most garage
type consumer units would have a 32amp type B for the ring main and this would generally be fine for a 'domestic' sized welder.
I would go for a 32amp (B) and see if that solves the problem but also make sure the wiring from the socket to the consumer unit is up to the job.
The other issue could be voltage drop though, how long is the feed from the house and can you see what size/ type of cable it is.....if its long and
small cable you will always have issues trying to run a welder on the end of it
Yes the MCB is in a unit in the garage. The cable looks a reasonable that comes into the garage through the floor, the length of the run from the
house to the garage is about 5 or 6 meters I would've thought.
I'll have a look at the cable through to the socket and if it looks substantial enough I'll try a higher rated B type first and see how I
go.
I hope it works! I haven't been able to get anything done since I've been in the new house!
Thanks,
Chris
Don't force it! Get a bigger hammer...
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robinj66
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| posted on 6/3/14 at 11:58 AM |
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You can't just look at the cable to see if it's up to the job.
You need to check the device for the max current draw and then check that the cable is up to the job.
The current rating should be marked on the cable - you have to make sure the cable can carry the load without failing -
This might help with the current ratings
You can use this tool to calculate Voltage Drop
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peter030371
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| posted on 6/3/14 at 12:10 PM |
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quote:
Originally posted by ChrisLeary
Yes the MCB is in a unit in the garage. The cable looks a reasonable that comes into the garage through the floor, the length of the run from the
house to the garage is about 5 or 6 meters I would've thought.
I'll have a look at the cable through to the socket and if it looks substantial enough I'll try a higher rated B type first and see how I
go.
I hope it works! I haven't been able to get anything done since I've been in the new house!
Thanks,
Chris
5-6 meters of decent cable should be fine but what sort of cable is it (twin and earth, armoured etc) and what is it marked with (you are looking for
the cable size in mm˛)?
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motorcycle_mayhem
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| posted on 6/3/14 at 12:46 PM |
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Just looked at my Hager box.
I have a 'NDN132A D32'
This does not trip.
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JoelP
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| posted on 6/3/14 at 05:04 PM |
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The b or c rating reflects how susceptible it is to tripping from the initial surge of current. B is normal, c is more resistant.
Do not up it to 32a, that's as bad as advice gets. If the cable connected to it could take 32a than the original spark would almost certainly
has fitted a 32a mcb in the first place.
16a breaker means it is most likely a 2.5mm twin and moon radial circuit, which iirc can take 22a in conduit. You need to identify the cable first.
Also identify the supply cable.
You will probably be able to sort your issues but don't just dive in with the new mcb. If you can give more info about cable sizes then I can
suggest a best solution.
Beware! Bourettes is binfectious.
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peter030371
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| posted on 6/3/14 at 10:32 PM |
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quote:
Originally posted by JoelP
The b or c rating reflects how susceptible it is to tripping from the initial surge of current. B is normal, c is more resistant.
Do not up it to 32a, that's as bad as advice gets. If the cable connected to it could take 32a than the original spark would almost certainly
has fitted a 32a mcb in the first place.
16a breaker means it is most likely a 2.5mm twin and moon radial circuit, which iirc can take 22a in conduit. You need to identify the cable first.
Also identify the supply cable.
You will probably be able to sort your issues but don't just dive in with the new mcb. If you can give more info about cable sizes then I can
suggest a best solution.
Did I not say 'make sure the wiring is up to the job'? If the wiring is sensible i.e. 2.5mm twin and earth then 32amp mcb is a perfect
match 
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JoelP
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| posted on 6/3/14 at 10:45 PM |
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If it's 16a and in a garage then it will be a radial, not a ring, which can't handle 32a. But as you said, it all comes down to
identifying the cable sizes and circuit layouts.
Beware! Bourettes is binfectious.
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