Workshop power supply

[Johnseat]

Afternoon people.
I've run 4mm armoured cable from the house to the workshop, the run is 22mtrs.
The online calculators state I'm can safely run a continuous 25amps with a maximum of just over 32amps so I was going to buy a 25mcb for the consumer and then a garage consumer for the workshop.
What ratings of rcbo should I be looking for, I know 6amp for lighting and 16amp for sockets but I want to install two 16amp blue sockets for my welders.
Can I just fuse spur off the 16amp welder circuit for my sockets or can I just run a radial around the walls and spur off for the welders?

Cheers.

 

[brightspark]

put a 32 amp in the house supply any less and u get nuisance tripping . if your using a 2 way garage unit the mains switch is an rcd so use a 6amp mcb for lights and a 16 amp for the radial feeding welder sockets and the 13 amp ones . no need for rcbo and the expense of them. run the 16 amp circuit in 2.5mm

 

[wookie]

Personally I prefer the lights to be on a separate RCD from everything else, that way when something trips out at least your not left in the dark.

 

[Johnseat]

put a 32 amp in the house supply any less and u get nuisance tripping . if your using a 2 way garage unit the mains switch is an rcd so use a 6amp mcb for lights and a 16 amp for the radial feeding welder sockets and the 13 amp ones . no need for rcbo and the expense of them. run the 16 amp circuit in 2.5mm

What ampage rcd should I use on the garage consumer, they normally come with a 40amp which is way over the top for me I think.

 

[123hotchef]

what cable did u use?

 

[Robotstar5]

What ampage rcd should I use on the garage consumer, they normally come with a 40amp which is way over the top for me I think.

The current rating (Amperage) of the RCD doesn't matter (as long as it's over 32A) as it's purely for earth fault protection, not overcurrent. the cable to the workshop is protected by the supply MCB and the lights & sockets are protected by 6A & 16A MCBs in the workshop CU.

 

[Robotstar5]

what cable did u use?

See post #1, 4mm² SWA...

 

[Johnseat]

Cheers @brightspark and @Robotstar5.
I'll pop out over the next few days and purchase my electrics.

 

[brightspark]

Personally I prefer the lights to be on a separate RCD from everything else, that way when something trips out at least your not left in the dark.

more money and how often do u trip something or get power cuts

 

[Johnseat]

One last thing, 8ve read on here to use a type C mcb for welders, is that safe for the radial sockets as well.

 

[brightspark]

b and c type will be ok through an rcd http://www.voltimum.co.uk/articles/selecting-right-mcb-its-easy-bcd

 

[wookie]

more money and how often do u trip something or get power cuts

Hardly ever but for the sake of a few quid it saves falling over something and hurting myself whilst trying to get to the consumer unit to reset it. I did that once in my previous garage and that was once too often, split my head open, my wife was worried sick when I came in the house covered in blood and it hurt like hell.

 

[Robotstar5]

Hardly ever but for the sake of a few quid it saves falling over something and hurting myself whilst trying to get to the consumer unit to reset it...

Install a non-maintained fitting above the CU fed direct from the lighting mcb so if it trips you have light to find and reset it, good idea to have one over the door/exit too.

 

[dobbslc]

I've got one over the door and if like me you have an old transformer welder or a 3hp compressor it will trip out at some point.....

My garage supply is on the same circuit as the kitchen ring so if I blow it the missus comes out shouting.

 

[knighty]

do you have a compressor ?

if you'r running your normal 3 pin sockets and your 16amp sockets from the same mcb you could trip if if your compressor kicks in while you're welding (or whatever)

I'd run two separate rings, half the 13amp sockets on each and one 16amp socket on each

in the long run MCBs and cable is cheap enough, it won't make much difference to cost

 

[Johnseat]

do you have a compressor ?

if you'r running your normal 3 pin sockets and your 16amp sockets from the same mcb you could trip if if your compressor kicks in while you're welding (or whatever)

I'd run two separate rings, half the 13amp sockets on each and one 16amp socket on each

in the long run MCBs and cable is cheap enough, it won't make much difference to cost

I will be having a compressor at some point and hopefully the largest 240v I can buy from machine mart.
What about a 16amp radial and a 20amp circuit for the welders and compressor?

 

[knighty]

that would work :-)

if you have plenty of space for MSBs, you could run one for all the 13amp sockets, and then one each for the 16amp sockets... if the sable it clipped to the wall and access is easy sometimes it's just as easy to run a separate mcb and socket for bigger loads

(no need for a ring etc.. just cable straight from msc to socket)

clipped to a wall 2.5mm is good for 27amps (bit more/bit less depending on who/where you ask, but either way it's plenty for you)


(if you're covering the cable, putting it in a wall or in conduit it's rated for a lot less 18amps iirc?)

 

[Johnseat]

Are you positive about the ampage rating if the cable is in plastic trunking.

 

[knighty]

I just checked again to make sure

clipped direct to the wall 2.5mm is good for 27amps

inside insulation 18.5amps


clipped to the wall the cable will naturally cool if it starts to warm up, inside anything insulating it it can warm up/get hot/melt so rating is lower

inside your plastic trunking you should run a ring to make sure there's plenty of capacity in the cable (better to be safe than sorry)

 

[Johnseat]

I'll just run it with clips and run a radial.