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| Tripping Breaker welding |
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| John Stevenson:
--- Quote from: Darren on April 05, 2010, 04:31:16 PM ---The RCD is fine, it's the MCB that's tripping. There is no fault, it's just that the MCB thinks there is when the welders transformer initially sucks juice from the wall ........ found it :) I have a type B MCB and I need a type C :dremel: http://www.tlc-direct.co.uk/Technical/Distribution/Mcb.htm --- End quote --- Get rid of the MCB and get a JCB. John S. |
| Fred Bloggs:
Darren My day time job is as building services electrical engineer, if you can tell me what the electrical specs for the welder are, the type of cable which is feeding the welder, its distance from the consumer unit and its CSA (cross sectional area) and I'll calculate what you should have. I also need to know whether your property is feed from overhead lines and therefore has a TT earthing system , or is your property feed via underground cable in which case the earthing system will be either TNCS or TNS, you need to know this as the earth fault currents and short circuit currents are/can be a lot lower with TT systems especially in rural areas. Also what type of consumer unit have you got, as you will probably have 32A type b miniture circuit breakers on the ring, the type "b, c or d" refers to the speed at which the breaker will operate at a give current, type b CB's trip at a lot lower current (are normally used for domestic installations) than type c or d CB's, type d are normally used for motor start applications which can have a starting current upto 10 times their rated current. I do not suggest that you just change your garage ring main circuit breaker for a type c or d as the breaker will not probably clear a genuine fault in the time allowed under BS7671 , "the wiring regs", hence my questions above, it would probably be easier and safer to run a suitably radial feed from the consumer unit to a dedicated socket in the garage (32Amp commando socket with isolator) Hope I can be of service Fred |
| Fred Bloggs:
Darren I'm that slow at typing 4 more posts have appeared before I put my reply up, take heed with my previous post dont just fit a 32A type c without a bit of maths!!!!!!!!!!!! :smart: Fred |
| John Hill:
--- Quote from: John Stevenson on April 05, 2010, 04:35:17 PM --- Get rid of the MCB and get a JCB. John S. --- End quote --- Carry it home in your HRG. |
| Darren:
Hi Fred, Thanks for the offer of help, I'm afraid it's been at least 20yrs since I last worked as an electrician and TBH I've shown little interest in it since then. So you could say I'm past my sell by date. The garage was built last year. All new materials were used esp for the electrical side of things. My earth is tied to neutral back at the power station. (overhead feed here) I rightly or wrongly, take your pick, fed the garage from one of the house consumer units (we have three ...erm make that five, but three main ones anyway) That is old but it does at least have trip fuses From there I took two runs of 4mm 3 core SWA cables 45m long (two of to minimise volt drop as I suspected some larger 3ph motors would be coming my way) These SWA's feed a new consumer unit with a 63A RCD and a 32A MCB for the ring main (2.5mm T&E 10 sockets, might be 12 I forget offhand) Lets say the ring is 30m from end to end, it'll be close enough. I'd go and have a look at the welders ratings, but I doubt it's going to give surge current details. I'll see if I can find it on the web ..... anything else you need to know? |
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