New summerhouse electrics help!

[Aibo82]

Hi
 
We are having a summerhouse in a few weeks and it will be used as a gym, we will require electrics in this summerhouse for lighting etc.
 
I am very competent in wireing and understanding some terms and regs of electricity but by no means a pro....
 
The summerhouse is roughly 15m away from the main Consumer unit in the house.
 
I would like to run a treadmill, a portable aircon maybe, a fan, 12v downlights, lcd tv/radio and maybe odd times the lawnmower from the sockets.
 
my intended plans:
 
GARAGE CONSUMER UNIT FITTED WITH A 30mA RCD AND TWO MCB'S: 6A + 16A
20m of 3 core  4mm gauge SWA cable burried deep in the grass with warning tape
2x double 240v 13amp sockets radial using 2.5mm T&E
 
Can I connect the SWA directly into the consumer box on a non RCD side this is the unit:

Can I then use the house earth or should I use an earth rod at the shed and isolate it from the house earth?

Thank you

 

[flameport]

GARAGE CONSUMER UNIT FITTED WITH A 30mA RCD AND TWO MCB'S: 6A + 16A
20m of 3 core  4mm gauge SWA cable burried deep in the grass with warning tape
2x double 240v 13amp sockets radial using 2.5mm T&E

Are 2 sockets on a 16A radial really going to be suitable for all of the equipment you want in there?
Lights and sockets on the same RCD does not comply - imagine what could happen when the RCD trips and someone is on the treadmill.
 

 Can I connect the SWA directly into the consumer box on a non RCD side this is the unit:

Not clear what you are meaning by 'non RCD side' - that box has no RCDs at all.
As there are no spare ways, no new circuits can be fitted to it.

Can I then use the house earth or should I use an earth rod at the shed and isolate it from the house earth?

What type of earth do you have at the house?

 

[PrenticeBoyofDerry]

You will need to follow part p guidelines for the routing of your cable.
It will need to be buried 600mm to protect the cable from tool damage also any potential ground movement must be considered. Ideally the cable should be capped using something like a coping stone and marked up with the electrical warning tape.
I would go with the 4.00mm 3 core SWA cable this can be protected at the house consumer unit by a 32A breaker, the 3 core SWA can also be terminated at the garage CU, must have 30mA RCD protection here for you circuits, you could then have 6A mcb for lighting circuit on 1.00mm T&E and 20 Amcb radial circuit on 2.5mm T&E.
This work is deemed as notifiable work.
So building controls must be informed prior to work starting and associated fees paid.
Good point made by flameport, regarding lights out and treadmill use.
Would consider RCBOs for individual circuits.

 

[holmslaw]

..

 

[PrenticeBoyofDerry]

I would also be looking at getting RCD protection on the shower circuit.

 

[ban-all-sheds]

We are having a summerhouse in a few weeks and it will be used as a gym, we will require electrics in this summerhouse for lighting etc.

How long can you wait while you learn all of the things you need to learn?

I am very competent in wireing

Sorry, but you aren't.

• For a circuit to supply a given load, how would you go about deciding what cable and protective device to use?
  
  
• Do you know which circuits can be ring finals and which cannot, and what the advantages and disadvantages of each are?
  
  
• Do you know what the two main lighting circuit topologies are, and what the advantages and disadvantages of each are?
  
  
• How do you calculate maximum demand and how can diversity be used?
  
  
• What are the 3 different types of domestic single-phase supplies provided in this country, how would you recognise them, and what differences do each make to the requirements for the rest of the installation, particularly any outdoor supplies?
  
  
• Can you correctly identify all components and connections of a circuit by method of testing or otherwise? In doing so can you identify or recognise anything wrong or dangerous with the circuit?
  
  
• Do you understand how the way in which you install cables affects how much current they can carry?
  
  
• What are the rules concerning cables concealed in walls, partitions and under floors?
  
  
• What are the rules for cables run outdoors, buried in the ground or overhead?
  
  
• Where cables need to be joined, how should this be done / not be done and in what circumstances are different methods acceptable?
  
  
• Can you identify extraneous conductive parts, and do you know the requirements for main and supplementary bonding of them?
  
  
• Which circuits should be RCD protected?
  
  
• How do you propose to isolate your supply so that you can connect up your new CU?
  
  
• Do you know what tests you would carry out on the installation - what sequence you'd do them in and at what point you would energise the installation, and for each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?

The thing is, wiring a building, installing new CUs, outside supplies, submains etc is not a trivial job, and I can assure you that it involves knowing far more than you think it does.

Asking questions here can be a useful part of a learning process, but they are not a substitute for proper structured studying. The key term there is "learning process" - you cannot learn all the things you need to know just by asking questions here. It isn't structured enough - it won't provide you with a way to progress where each step builds on what you learned before.

You can't carry out a job of this magnitude by asking whatever random questions happen to occur to you. You've already shown that you have some dodgy misconceptions - what if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

• //www.diynot.com/wiki/electrics
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• http://www.tlc-direct.co.uk/Book/1.1.htm[/list]I suggest you get stuck into the last link right away - it won't give you design ideas, and unfortunately it doesn't refer to the current edition of the Wiring Regulations, but it's free, and will still give you a good grounding which you can augment with more up to date publications.
  
  
  

  Can I connect the SWA directly into the consumer box on a non RCD side

  As flameport pointed out, there is no RCD.
  
  But even so, surely you can see that the box is full? What did you think you'd do without to get the summerhouse connected? Shower? Cooker?

 

[Aibo82]

In the summerhouse:

I would of connected the lights the 6a rcd
and the sockets the the 16amp rcd

The shower was installed by an electrician who said get a replacement mcb that was 40amp there used to be a fuse holder in that box rated 30amp

The earth in 2 earth rods near the meter then tagged pipework

Sounds now like a big job!

 

[sparkybird]

Also you can't connect SWA into your consumer unit (even if there was space) as it's plastic not metal.

Me thinks it's time to call a sparks.....

SB

 

[Monkeh]

Also you can't connect SWA into your consumer unit (even if there was space) as it's plastic not metal.

Sure you can, assuming there's free space to cut a hole and the cable is correctly supported.

 

[riveralt]

Also you can't connect SWA into your consumer unit (even if there was space) as it's plastic not metal.

Sure you can, assuming there's free space to cut a hole and the cable is correctly supported.

Where is the free space in that consumer unit?
It already exceeds the 63Amp isolator - even allowing for diversity.

 

[Monkeh]

Also you can't connect SWA into your consumer unit (even if there was space) as it's plastic not metal.

Sure you can, assuming there's free space to cut a hole and the cable is correctly supported.

Where is the free space in that consumer unit?
It already exceeds the 63Amp isolator - even allowing for diversity.

I mean physical space on one side for the gland. I wasn't referring to this CU in particular, but the broad statement that you can't fit SWA to a plastic enclosure.

 

[xr4x4]

So we are talking henleys, mini CU with single rcbo, or mcb and rcd? Feeding swa?

Or a complete board change.

 

[RF Lighting]

PIR leading to a board change I'd have thought.

 

[ban-all-sheds]

The board change is a separate issue, and I'd keep it electrically separate from the summerhouse supply anyway, no matter what it was like, with henleys, and a switchfuse for the SWA to a CU in the outbuilding.

 

[Aibo82]

Sounds like a nightmare!

We be here 15yr and that CU was here befor we got here. the garage used to be fed on a T&E 2.5mm cable from a socket junction box up in the attic but was pulled out when the kitchen was done.

Did not think it would be hundreds of pounds for a light and a few sockets in a summerhouse!

as for the shower RCD I find conflicting information if it should have one or not, the last electriction 5-6years ago said just get a 40amp mcb to replace the fuse holder in the CU.

He did it but the cover bulges because its to big thats running a 10kw shower on 10mm T&E

Did not relalise it was so bad?