Cable Size

[Seano]

Finally getting round to finishing the sockets and moving onto the wiring today, I know what size cable I Should use, but times being a bit frugal at present I have ten meters of new 6mm cable lying around, so,STARTING WITH would there be anything wrong in using that to a 32A interlocked switch for my mig, then through into a 16A interlocked switch for my tig,then through to a bank of 4 twin outlet sockets in one of those wall runs seen in offices (had some from a revamp at work) obviously not all outlets will be worked simultaniously ?

 

[wheresmejumper]

edit: misread

 

[piman]

Hello Sean,

You really need to have three separate circuits for the different sockets each with their own breaker.

Alec

 

[Seano]

Strange, the electrician that does all the work where i work looked at it and said perfectly legal and practical to do that.

 

[madkayaker]

If the whole lot was fused at 32a and the 16a socket was fused down to 16a then I can't see any problem. I would not do it like that as there is chance of the loads adding up to higher than the 32a but that will trip mcb not cause problems. I would certainly rcd the job as well for extra protection of user

 

[Seano]

I think I did state that sockets would not be used simultaniously, after all, I only have one pair of hands......and even then they work slowly, to recap MK, I could drop the main supply down to a junction box, T off that to a 16a fuse for the tig, and then carry on down to the 32a interlock mig box, also supplying the bank of 13a outlets.

 

[brightspark]

I think I did state that sockets would not be used simultaniously, after all, I only have one pair of hands......and even then they work slowly, to recap MK, I could drop the main supply down to a junction box, T off that to a 16a fuse for the tig, and then carry on down to the 32a interlock mig box, also supplying the bank of 13a outlets.

why dont u just buy a 3way db there only peanuts. a 32a mcb and a couple of 16 amp and run 3 radials out, u should have lived local to me i scrap more cable than u would have needed and chuck the breakers away

 

[Seano]

why dont u just buy a 3way db there only peanuts. a 32a mcb and a couple of 16 amp and run 3 radials out, u should have lived local to me i scrap more cable than u would have needed and chuck the breakers away

I did many years ago.... Got the 32a mcb, 3way db ? ? ? 16 amp what ??? Any clues, links....

 

[madkayaker]

I think I did state that sockets would not be used simultaniously, after all, I only have one pair of hands......and even then they work slowly, to recap MK, I could drop the main supply down to a junction box, T off that to a 16a fuse for the tig, and then carry on down to the 32a interlock mig box, also supplying the bank of 13a outlets.

Yes. HOWEVER the 16 socket must be protected my a 16 fuse. A fuse box would be a good way to add future use and then the cable sizes can be reduced to the 16 socket and to the sockets

 

[Robotstar5]

I did many years ago.... Got the 32a mcb, 3way db ? ? ? 16 amp what ??? Any clues, links....

4 way DB but 2 of the ways are needed for the incomer (local isolation) so probably better to go for the 8 way you then add a 32A mcb for the 32A outlet, a 16a mcb for the 16A outlet, a 32A mcb for 13A sockets if done in a ring or 20A mcb if done radial and finally a 6A mcb for the lights.

The incomer linked is assuming you have RCD protection on the feed to the workshop else it will be replaced with an RCD type (a lot dearer!)

edit: you won't be able to wire your 13A sockets with 6mm cable, it won't fit!

 

[brightspark]

4 way DB but 2 of the ways are needed for the incomer (local isolation) so probably better to go for the 8 way you then add a 32A mcb for the 32A outlet, a 16a mcb for the 16A outlet, a 32A mcb for 13A sockets if done in a ring or 20A mcb if done radial and finally a 6A mcb for the lights.

The incomer linked is assuming you have RCD protection on the feed to the workshop else it will be replaced with an RCD type (a lot dearer!)

edit: you won't be able to wire your 13A sockets with 6mm cable, it won't fit!

4.0mm max on a radial for sockets with a 30 amp breaker. better off with 2.5mm and a 20 amp breaker on radial

 

[Seano]

After all these posts it's starting to get confusing, I think it's time to bite the bullet save some cash up and call an electrician in, between being hospitalised and cashflow this job will never get finished.......

 

[madkayaker]

Use your 6mm to get from your main fuse box to a small fuse box in garage (RCD main switch. 32A MCB for 32A socket, 16A MCB for 16 socket and 20A for plugs) then use left over 6mm to get to 32 socket, 2.5mm for 16A socket and 2.5mm for plugs (that might be very slightly under sized with new regs but as long as there is no insulation and cable length is fairly short will be fine. Current carrying capacity was down graded with the changing of the regs in 2008)


You could use your 6mm for everything but you will struggle to physically get the cable into the terminals on sockets! (As you will have one cable in and one cable out)

 

[Wedg1e]

2.5mm for plugs (that might be very slightly under sized with new regs but as long as there is no insulation and cable length is fairly short will be fine. Current carrying capacity was down graded with the changing of the regs in 2008)

What? Are they now saying bigger than 2.5mm sq. for 3-pin sockets? It's hard enough to get 2 lengths of T&E into a shallow pattress as it is!

 

[madkayaker]

They are. Sockets are not an issues as there not supposed to be used in box less than 25mm. It's fuse spurs that are fun you have to remember to use 2.5mm on fused out put. Also with the increased level of insulation cables have gone up a lot in size. Try getting 16mm twin in a shower pull switch!

 

[Wedg1e]

They are. Sockets are not an issues as there not supposed to be used in box less than 25mm. It's fuse spurs that are fun you have to remember to use 2.5mm on fused out put. Also with the increased level of insulation cables have gone up a lot in size. Try getting 16mm twin in a shower pull switch!

Good grief.

We're just about to build a mobile darkroom which will need full electrics, I'll have to bring this to management's attention

 

[madkayaker]

Get your self off to college and do the wiring regs ticket (2381 or 2382) there has been lots of changes since the 16th edition

 

[Robotstar5]

Good grief.

We're just about to build a mobile darkroom which will need full electrics, I'll have to bring this to management's attention

Your're better off (safer) getting an up to date sparky in who'll be able to install, test and supply certs for the job as in your type of business I'm sure a "papertrail" is required for traceability?.

 

[Wedg1e]

Your're better off (safer) getting an up to date sparky in who'll be able to install, test and supply certs for the job as in your type of business I'm sure a "papertrail" is required for traceability?.

Good point: our sister company does site electrical installations so they probably have someone who can 'oversee', if not do the actual work.

To make matters worse it's an offshore unit so has to be fire-resistant, corrosion-resistant and squaddie-proof

 

[madkayaker]

There is a whole raft of requirements for off shore EX rated stuff. Might be worth speaking to fhttp://www.thorneandderrick.co.ukor there advice they do consultancy work for off shore kit.