Electrics for shed

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I am planning on building a new shed near my house. Shed will be around 2.5m x 2.5m.

Conveniently there is a socket inside the house near where the shed will be situated. I think this socket is on a ring (need to check).

Q. Would it be okay to take a feed from this socket to a FCU in the shed (buried in appropriate conduit). The FCU will then feed some sockets and a couple of lights. I envisage having a chest freezer and tumble dryer in here at a later date.

Thanks in advance.
 
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You would need an FCU at the house end. 13Afuse. That protects the house ring in the event of damage to the cable feeding the shed*
It also allows you to fully isolate the shed feed if you need to.

In the shed, connect up to your two sockets and fit another FCU with a 3A fuse for the light.

* important questions
Is the circuit you plan to feed from 30mA RCD protected?
How will you run a cable from the house to the shed?
What sort of cable?
 
Hi @Taylortwocities, I’m finally about to embark on this project. Sorry for the delay in responding!

It will be easier to get power from the garage as this is closer to the shed than the house. The garage is on a submain with an armoured cable coming from the house. There is a consumer unit in the garage and it has a ring main running of an 32MCB.
I could punch a hole out of the closest socket out to the garage with a stub of 2.5mm T&E. this would go into the box for the armoured cable. The armoured cable will then be buried into the ground and go around 3 metres to reach the new shed. The armoured cable can then be terminated into another box in the shed and from here, I think you’ve suggested that I feed a FCU with 13AMP fuse followed by another FCU with 3AMP fuse. The sockets can then be wired as a radial from the 13AMP FCU and lights in the usual way off the 3AMP FCU.

I’ve also noted your suggestion on a 13AMP FCU in the garage after I spur off a socket and before I punch out to the armoured cable.

Can I have your comments on the above please. Thanks for your help
 
Can we take a step back, You said
The garage is on a submain with an armoured cable coming from the house.

How is this connected at the house end?

Is it an MCB on the house consumer unit? What value MCB?
Is it a switch fuse, with meter tails direct from the supply? what value fuse?
Is it from an FCU on an existing ring final circuit?

The answer to this will greatly affect the answers to your queries.
 
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Hi @Taylortwocities,

Here's some additional info as requested.
Inside the house, I have the following:
upload_2020-5-31_20-52-19.png


The armoured cable going into the Consumer unit in the garage is connected in side the metal box shown above.
The breaker for the garage is B16. Seen clearer in thus image:
upload_2020-5-31_20-53-39.png


This appears to control power to the garage. I believe that I have a 10mm armoured cable.

Inside the Garage, we have this consumer unit:
upload_2020-5-31_20-55-24.png


The Ring Main that I would want to spur off is powered by the B32 breaker.

I hope this answers your questions and look forward to your guidance.
 
Did you install that?

First of all, there is absolutely zero point in having a 32Amp MCB in the garage. The maximum current draw cannot be more than the 16A.
so installing a ring final on a 32A mcb is pointless.
All current limiting devices should be designed so that the largest is at the source, and smaller ones at the load end.

Given the state of the house fuseboard, you should be ripping that old Wylex board out and replacing it with the twin RCD unit from the garage!

But I guess we have to deal with a right mess…


What do all those MCBs in the garage Do? Where are the labels? Are any of them spare?

Re the SWA size. You say it’s 10Mm². Nobody in their right mind would put a 16A MCB on 10mm² SWA. What makes you think it’s 10mm². How did you measure it?
 
My first thought was "" Is the meter in the garage by the dual RCD consumer unit and that consumer unit is feeding the one in the house. ""

But there is a ceramic mount, board and maybe meter tails visible next to the non RCD consumer unit so my first thought has to be wrong......doesn't it ?

What a strange un-designed installation.
 
I should have stated, I did not install this and it predates us.
Your observation on the higher ratings downstream now seem like an obvious flaw...

My neighbour who fixes air conditioners for a living commented that the armoured cable is 10mm. It seems very thick to me.

All the breakers in the garage are being used for different purposes: lights, sockets (sockets appear to be on individual breakers in some cases), electric garage door and a electric cooker point as it was once used as an Annex.
 
The 16A MCB in the right hand half of the MK board. What is that for?

Re the SWA size. “Very thick” doesn’t help. Most SWA cable has the size embossed on the outer sheath. It may say something like 2x10, or 3x6.
What’s on yours?
 
All the breakers in the garage are being used for different purposes: lights, sockets (sockets appear to be on individual breakers in some cases), electric garage door and a electric cooker point as it was once used as an Annex.
If that garage CU (with all those circuits) really is fed from a 16A circuit in the house CU, that's a complete joke, and I have to wonder, for example, whether whoever once used the place as a 'annex' ever got to cooker to work without being plunged into darkness :)

Kind Regards, John
 
I couldn't see any text on the cable. I have put a tape measure next to the cable to provide an indication on size:
upload_2020-6-2_11-56-9.png


Excuse the fuzzy pic but you should be able to see that this is almost 2cm.

The 16A MCB is used by the electric garage door.

Thanks again.
 
Hi @Taylortwocities,

Here's some additional info as requested.
Inside the house, I have the following:
View attachment 194381

The armoured cable going into the Consumer unit in the garage is connected in side the metal box shown above.
The breaker for the garage is B16.
I'm struggling to see the cable feeding the silver box, it almost looks like tails [I'm outside in the sun so struggle with the image], I think I see a wire wrapped with green/yellow and 2 more.

That could easily be 2 or 3 core 10mm².

I wonder if the B16 may have been bigger in the past.

Anyway back to your requirements, I'd suggest connecting directly off the garage CU rather than messing with tapping into a ring/FCu's etc. but other things need to be looked at/sorted first.
 
3 core 10mm² SWA outside diameter is nominally 18.9mm. But it’s the csa if the live conductors that matters.
Youve probably room for increasing capacity, Above 16amp, On the SWA, but have this assessed by a registered electrician when you have that fuseboard mess replaced.

in the meantime, I suggest that you simply add your additional socket to the garage door 16A MCB. Use 2.5mm cable.

Sorted.
 

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