UK MCB Size for radial socket circuit.

[Toonjabba]

My shed is only 5 Meters from my house, i will run a SWA cable from existing consumer unit to a shed consumer unit which will have 3 circuits for Sockets,Light and a 7.5Kw shower unit all i need to know is will a 16 Amp MCB be sufficient for the socket Radial circuit for 4 Double sockets

 

[Petej999]

My shed is only 5 Meters from my house, i will run a SWA cable from existing consumer unit to a shed consumer unit which will have 3 circuits for Sockets,Light and a 7.5Kw shower unit all i need to know is will a 16 Amp MCB be sufficient for the socket Radial circuit for 4 Double sockets

No 16 A far to small, 7,5 KW SHOWER WILL TAKE APPROX 32 Amps on it's own, needs it's own dedicated circuit, should not be connected to a socket radial circuit. what siz cable will you be using for the radial?

 

[timhoward]

No 16 A far to small, 7,5 KW SHOWER WILL TAKE APPROX 32 Amps on it's own, needs it's own dedicated circuit, should not be connected to a socket radial circuit. what siz cable will you be using for the radial?

I think the OP said there will be 3 circuits in the shed, and the question might have been regarding one of them, the sockets circuit.
There are bigger questions though, since a shower means a water supply, which could mean extraneous things to bond etc, and could have implications on the size of SWA used.
There are actually quite a few complex design considerations regarding earthing and bonding. I'd highly advise you to get your plans checked out by someone qualified.
For the record, this work is notifiable work under part P of building regs as you are both installing new circuits and (by the sounds of it) turning the shed into a special location.

 

[Petej999]

I think the OP said there will be 3 circuits in the shed, and the question might have been regarding one of them, the sockets circuit.
There are bigger questions though, since a shower means a water supply, which could mean extraneous things to bond etc, and could have implications on the size of SWA used.
There are actually quite a few complex design considerations regarding earthing and bonding. I'd highly advise you to get your plans checked out by someone qualified.
For the record, this work is notifiable work under part P of building regs as you are both installing new circuits and (by the sounds of it) turning the shed into a special location.

I think the OP said there will be 3 circuits in the shed, and the question might have been regarding one of them, the sockets circuit.
There are bigger questions though, since a shower means a water supply, which could mean extraneous things to bond etc, and could have implications on the size of SWA used.
There are actually quite a few complex design considerations regarding earthing and bonding. I'd highly advise you to get your plans checked out by someone qualified.
For the record, this work is notifiable work under part P of building regs as you are both installing new circuits and (by the sounds of it) turning the shed into a special location.

miss read the OP Tim my bad

 

[Toonjabba]

That’s good. I am qualified but not done electrical work for a while now so just checking. All I need to know really is the size of the MCB in the house consumer unit going to the CU in the shed

 

[telectrix]

50AMCB 10mm cable or 63A MCB and 16mm cable. all depends on the total design load. esp with a bloody hot rain bath

 

[Toonjabba]

50AMCB 10mm cable or 63A MCB and 16mm cable. all depends on the total design load. esp with a bloody hot rain bath

The shower is the only big thing being used. It’s for dog grooming the other things will be a single strip light some trimmers and a hair dryer. Was hoping to get away with 6mm SWA as I have some left over in the shed. But I will take your advice. Thanks for the help

 

[Toonjabba]

The shower is the only big thing being used. It’s for dog grooming the other things will be a single strip light some trimmers and a hair dryer. Was hoping to get away with 6mm SWA as I have some left over in the shed. But I will take your advice. Thanks for the help

What if I got a 5kw shower instead

 

[telectrix]

even 7kW shower would be OK using a 6.0mm feed on a 40A MCB. efli being satisfied.

 

[pc1966]

Going 10mm 3-core SWA at least makes sure you can meet any TN-C-S supply bonding requirements, usually good to 50A MCB but that depends, of course, on the supply Zs.

Also be aware that any new circuit (or CU) is notifiable work in England and Wales under part P of the building regulations. It might be safer, cheaper, and easier to get someone registered with one of the schemes (NICEIC, NAPIT, etc) to sort it out, even if you do the donkey work of digging trenches, etc, for the cable to go in.

 

[Toonjabba]

even 7kW shower would be OK using a 6.0mm feed on a 40A MCB. efli being satisfied.

Awesome cheers for that.

 

[Toonjabba]

even 7kW shower would be OK using a 6.0mm feed on a 40A MCB. efli being satisfied.

So I can run 6mm SWA cable 40A MCB from house to shed. Then I will run 3 separate circuits from shed CU for sockets lights and shower.

 

[telectrix]

bear in mind that your sockets will be limited. the shower takes upmost of the 6mm capacity. personally, I'd fit a 3kW under sink heater to activate when you turn the tap on. dog's only need warm water for grooming. anything above 45 degrees is too hot.

 

[Electrics]

For the 4 double sockets you can use a 16a breaker and 1.5mm T+E.

 

[Toonjabba]

bear in mind that your sockets will be limited. the shower takes upmost of the 6mm capacity. personally, I'd fit a 3kW under sink heater to activate when you turn the tap on. dog's only need warm water for grooming. anything above 45 degrees is too hot.

So I wouldn’t need a shower just the heater

 

[Toonjabba]

So I wouldn’t need a shower just the heater

It would just go into a mixer shower

 

[Toonjabba]

It would just go into a mixer shower

Sorry. Just to add could I connect to a fused spur off the socket in the shed

 

[DPG]

For the 4 double sockets you can use a 16a breaker and 1.5mm T+E.

But would surely be better on some 2.5 and a bigger MCB.

 

[Electrics]

But would surely be better on some 2.5 and a bigger MCB.

Depends what it's for imo. In Europe it's quite common to see 16a and 5 sockets, and it will manage several tellies, chargers, a hoover, lamp, laptop etc.

In a shed maybe he wants to run power tools or maybe just plug in a radio?

Personally i would still do it in 2.5mm and 20a but 16a is doable.

 

[DPG]

Depends what it's for imo. In Europe it's quite common to see 16a and 5 sockets, and it will manage several tellies, chargers, a hoover, lamp, laptop etc.

In a shed maybe he wants to run power tools or maybe just plug in a radio?

Personally i would still do it in 2.5mm and 20a but 16a is doable.

Just wondered why you recommended 1.5mm and 16A. Seems a bit tight for 4 double sockets.