Garage wiring

[cprfenom]

Got a customer that is toying with the idea of a garage supply for some welding gear and a plasma cutter. As it stands at the moment he has a TN-C-S arrangement and 100A Bs1361 service fuse and 32A RCBO type B breaker in his consumer unit. It is feeding a 2 way garage board with a 16A and 6A breaker. When using his 2KW transformer it is sometimes tripping and has decided on beefing up the supply.

My question is if I come off a henley block just after an isolator, but before the consumer unit and then feed from a 63A isolator in 16mm SWA would you still recommend TT'ing the garage? The run from the house is approx 20 metres.

Kind regards,

Chris

 

[davesparks]

What is tripping?

 

[Pete999]

What davesparks said, we need to know what is tripping

 

[Geordie Spark]

What is tripping?

It's the experience you have when you're out of your tree on LSD.

 

[Pete999]

It's the experience you have when you're out of your tree on LSD.

You been there then Geordie???

 

[Geordie Spark]

You been there then Geordie???

I have. Just once back in '67 I think and it was a bad experience which I have no desire to repeat.

I was the Black Sheep of the band because I was the only one who didn't "do drugs".

 

[Octopus]

Ok. I'll hazard a guess that the 16a mcb is tripping!

Edit: as it's a type b and should probably be a type c

 

[Silly Sausage]

Ok. I'll hazard a guess that the 16a mcb is tripping!

I'm going for the RCBO tripping on leakage from the possibly suspect transformer.

 

[cprfenom]

Yes the rcbo is tripping via the transformer on the odd occasion and he is wanting to use more gear. As it stands its a small welder and the 2kw transformer, but he wants to put in some more lighting and introduce a larger welder and plasma cutter. He has informed me the welder he wants is on a 16A plug and wants to beef up the supply to his garage.

If he was just keeping what he had then I wouldve just changed it to a type C MCB, but what he has wont stand up to running bigger gear.
The question was more about earthing arrangements if I were to do this.

Kind regards,

Chris

 

[snowhead]

Not forgetting that to use a Plasma cutter you also need an air compressor running at the same time.

 

[Pete999]

I have. Just once back in '67 I think and it was a bad experience which I have no desire to repeat.

I was the Black Sheep of the band because I was the only one who didn't "do drugs".

Good for you mate, I got caught up in Amsterdam with the dodgy cake, never again, seen too much heartache due to drugs.

 

[Darkwood]

Yes the rcbo is tripping via the transformer on the odd occasion and he is wanting to use more gear. As it stands its a small welder and the 2kw transformer, but he wants to put in some more lighting and introduce a larger welder and plasma cutter. He has informed me the welder he wants is on a 16A plug and wants to beef up the supply to his garage.

If he was just keeping what he had then I wouldve just changed it to a type C MCB, but what he has wont stand up to running bigger gear.
The question was more about earthing arrangements if I were to do this.



Kind regards,

Chris

Refer to the manufacturers guide as to protective device size, they are now required to inform you in the installation guide or user instructions... as we don't know what hes getting then our advice can at best only be speculative and may be wrong and finally why would you want to TT the garage is their a reason why?

 

[cprfenom]

Personally no reason I would want to TT a garage, but I wasn't really seeing what others felt. In terms of load its speculation as he does not have the gear as yet, hence putting in 16mm swa with a 63A backing that up.

 

[Darkwood]

If you use a 16mm swa with 3cores then the 3rd core can be earth and used for any bonding requirements in the garage ...the armour will be also earthed for the needs of the circuits, if you have no structural or incoming services in the garage that require equipotential bonding then you could just use a 2core swa and utilise the armour as the earthing for the circuits, but I'd still be inclined to fit 3-core anyway because the welder etc may require type D's large mcb's and this has a tight ELI to meet.

Problem with plasma cutters and welders etc is the inrush and if you get the protection wrong you get nuisance tripping thats why you need to wait to he's decided what hes getting it may alter the set-up of your install.

You could play it safe and use a switchfuse up front with 63amp HRC fuses in and then hope he gets nothing too hefty but with respect your average plasma cutter is not designed for domestic set-ups so Ill play that one by ear.

 

[cprfenom]

I generally earth the armour at source and use a core as the functional earth. Thanks Darkwood, that was pretty much what I was thinking in terms of design and you've put my mind at ease.

Regards,

Chris