Advice on how to run power/lights to 2 sheds?

[uptown47]

Hi all,

I want to run electric to two sheds. The sheds are located about 15 metres from the main house and are located together (probably a couple of metres between them).

I wanted to seek advice from those 'in the trade' as to the best way to do this. I do have a plan but need to make sure that it's ok.

Firstly, I need to point out that I'm a competent "DIY'er". I have done work on electrics before but I've never run power outside.

The house has an old 6mm twin/earth cable that runs outside (the previous owner used for a hot tub). This goes back to it's own breaker on the distribution board and also runs through a large 32 amp switch before going outside.

When we moved in this cable was just coiled up outside. I needed an outdoor socket so I buried the cable around the bottom of the house and connected it to an outdoor socket.

My plan was to 'spur' off this socket with 4mm armoured cable clipped along the side of the house (probably run straight up to the top of the house and then along under the eaves), run it around to the side of the house, down to the base of the fence and then run it through maybe some 'milk pipe' (basically 1" diameter stainless pipe) along the bottom of the fence to the first shed. Then take it to a distribution board in the first shed and have breakers for the lights/sockets in the first shed. And breakers for the lights/sockets in the second shed.

To connect the second shed I was thinking of running a bit of galvanised trunking at high level between the two sheds and then tie wrapping armoured cable to it?

Also worth noting that this is our 'forever' house but if we do sell it I would simply disconnect the 6mm cable from the distribution board and leave it to the new owners to reconnect if they wanted.

So... advice/questions....

I realise that you shouldn't 'spur' from what is technically a spur (ie. the outside socket that comes from the 6mm cable) but I'm thinking that because the outside socket is very occasional use (mowing the lawn every week) and it's being fed by a 6mm cable then it should be ok ?? (thoughts?)

Am I allowed to simply 'clip' or 'cleat' the armoured cable to the outside brick of my house? Or does it have to run inside conduit or some such??

Is running the cable through conduit/milk pipe at the bottom of the fence the way to go or should I look to bury it? If so, how deep and can I just bury the armoured cable as is? Or does it still need to run inside something?? (I'm wondering whether rodents would nibble through it etc)??

To connect both sheds is it sufficient to have one distribution board and feed the two sheds? Or would they need a distribution board each??

Is it ok to run the armoured cable at high level between the two sheds? Or would it need to be buried or run inside conduit etc??

I am aware that an easy answer to these questions is to get a "qualified electrician" but I would like to do this work myself. I am very dilligent and capable and my work tends to be a lot neater than a lot of 'proper' tradesmen so this certainly won't be a 'hash job'. I just want to get advice on *how* to achieve it in the best possible way?

A big thank you for any help you can give me on this.

Cheers

 

[ban-all-sheds]

When we moved in this cable was just coiled up outside. I needed an outdoor socket so I buried the cable around the bottom of the house and connected it to an outdoor socket.

You should not have done that - T&E is not suitable for installation that way.

As you are now doing more work related to that circuit I suggest you disconnect it, cable the socket properly and forget it is there.

My plan was to 'spur' off this socket with 4mm

The circuit currently used 6mm².

What rating is the protective device? Will 4mm² be OK on it?

What is your design load? Will 4mm² be adequate?

Have you worked out what volt-drop will be?

• http://www.google.co.uk/search?q=cable+installation+methods+17th+edition
  
  
• [wiki]Electrics%3AMCBtoCable[/wiki]
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• http://web.archive.org/web/20070327014113/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html <- Specify 2-core cable and PVC, even if that is not what you are using or it will make invalid assumptions.
  
  
• http://www.batt.co.uk/upload/files/4d5.pdf
  
  The references above which are in italics are out of date. The principles are still valid, and you can absolutely learn valid things from them, but you will need to refer to the latest edition of the Wiring Regulations to get the correct data.

armoured cable clipped along the side of the house (probably run straight up to the top of the house and then along under the eaves), run it around to the side of the house, down to the base of the fence and then run it through maybe some 'milk pipe' (basically 1" diameter stainless pipe) along the bottom of the fence to the first shed. Then take it to a distribution board in the first shed and have breakers for the lights/sockets in the first shed. And breakers for the lights/sockets in the second shed.

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?

Are you aware that you need, and do you intend to apply for, Building Regulations approval for this work?

If you have extraneous-conductive-parts in the sheds, and you have a TN-C-S supply, have you thought about whether you will export the supply earth or not?

To connect the second shed I was thinking of running a bit of galvanised trunking at high level between the two sheds and then tie wrapping armoured cable to it?

Cable tray would be better, as it won't fill with water.

Or just a support wire.

Also worth noting that this is our 'forever' house but if we do sell it I would simply disconnect the 6mm cable from the distribution board and leave it to the new owners to reconnect if they wanted.

Why would you do that? What would there be about your work that you would not want others to be exposed to it? What transfer of liabilities and/or resolution of issues do you think would happen if you did that?

I realise that you shouldn't 'spur' from what is technically a spur (ie. the outside socket that comes from the 6mm cable) but I'm thinking that because the outside socket is very occasional use (mowing the lawn every week) and it's being fed by a 6mm cable then it should be ok ??

It's not a spur.

(thoughts?)

That you don't really know enough.

Am I allowed to simply 'clip' or 'cleat' the armoured cable to the outside brick of my house? Or does it have to run inside conduit or some such??

If, having exercised reasonable skill and care, a clipped cable would, to the best of your knowledge and belief, not come to any harm then you are allowed.

Is running the cable through conduit/milk pipe at the bottom of the fence the way to go or should I look to bury it?

Again, if you think it will be OK like that...

The biggest problem with fences is that they move in the wind (and in extremis get blown down), so cables attached to them get continually flexed, joints get continually pulled, etc.

If so, how deep and can I just bury the armoured cable as is? Or does it still need to run inside something?? (I'm wondering whether rodents would nibble through it etc)??

Guidance on burying cables:

https://www.tlc-direct.co.uk/Book/7.13.3.htm

SWA can be directly buried, but it makes any future replacements or additions easier if you use ducting.

To connect both sheds is it sufficient to have one distribution board and feed the two sheds? Or would they need a distribution board each??

It's probably sufficient to have no CU or DB, and probable that neither needs one.

If you want one that's a different matter.

Is it ok to run the armoured cable at high level between the two sheds?

How high, and do people pass beneath it?

I am aware that an easy answer to these questions is to get a "qualified electrician" but I would like to do this work myself. I am very dilligent and capable and my work tends to be a lot neater than a lot of 'proper' tradesmen so this certainly won't be a 'hash job'. I just want to get advice on *how* to achieve it in the best possible way?

There's more involved than just neatness.

Testing.

Proper sizing of the sub-main.

Building Regulations approval.

Consideration of TN-C-S export, discrimination between devices in the shed and ones in the house.

The thing is 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?

"Get an electrician" is not just an easy answer, it really is the best advice.

 

[chivers67]

Burying SWA you normally run it deep enough to avoid a spade so at least 10 to 12 inches and it doesn't require ducting as already mechanically protected . Normally have to place over it some warning tape too so if it is dug up unless you're a complete idiot you'd know there's a live cable underneath.

You can cleat armoured cable to buildings but it does look unsightly and bending it suitable makes it very awkward.

I really think you should consider getting an electrician to do this work or at least come round to discuss it in detail, this work is notifiable and could lead to a hefty fine if done incorrectly it just sounds a bit of an oddity and from your description of running it sounds like it will not only look terrible but be awkward too.

You'd be making the radial circuit longer rather than spurring as such.

They'll be more advice along...

 

[uptown47]

ban-all-sheds, chivers67,

A big thanks for all your help with this. The advice is greatly appreciated.

I thought it would still be called a 'spur' even though it's just extending a radial circuit so thanks for clearing that up.

I've checked the voltage drop / power usage and 4mm cable would be more than enough.

I've cleated cables to buildings before but it was many years ago when I worked in a factory and wasn't sure if it was ok for domestic premises. I should look ok as it will be cleated up an inside corner of the building (if that makes sense) and then will run along under the eaves at high level so will largely be invisible.

I'll have a look into burying the cable but it's good to know that I could clip to the fence if needed. I think I would run inside conduit if doing this though to afford greater protection.

The span between the sheds will be well above head height so shouldn't cause any problems. Obviously I'll bear rain in mind when choosing a suitable means of transporting the cable between sheds.


Chivers67, I really like your idea of getting a spark round to talk about the job. I think I'll get someone in to discuss it with me and then see if they would agree to return and 'test' the job after I've completed it. I've got a friend of a friend in mind for this so I'll see if they would agree to this (basically me doing the donkey work and then giving them bit of cash to sign it off at the end).

Although from reading the advice so far all this seems very do-able (albeit with a lot more reading to do at my end first!).

To be completely honest I wasn't planning on "notifying" anyone of the work? Are you talking about telling the council?

Thanks again for all the advice so far. Really appreciated. Cheers

 

[chivers67]

http://www.electricalsafetyfirst.org.uk/guides-and-advice/building-regulations/scotland/ < Click link Johnny

 

[uptown47]

Got it... thanks

 

[ban-all-sheds]

I've checked the voltage drop / power usage and 4mm cable would be more than enough.

So a 15-20A load? Definitely no need for a CU for a few sockets and lights. Unless you go for the sensible idea of getting the supply to the sheds off the house CU altogether.

I think I'll get someone in to discuss it with me and then see if they would agree to return and 'test' the job after I've completed it. I've got a friend of a friend in mind for this so I'll see if they would agree to this (basically me doing the donkey work and then giving them bit of cash to sign it off at the end).

Bear in mind the declaration on an Electrical Installation Certificate:

I being the person responsible for the design, construction, inspection & testing of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the design, construction, inspection & testing hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008, amended to 2015 except for the departures, if any, detailed as follows:

Don't ask the guy to sign for something he really didn't do.

To be completely honest I wasn't planning on "notifying" anyone of the work? Are you talking about telling the council?

You're in Scotland - I'm not familiar with their rules - I didn't think to check your location earlier when I said the work was notifiable.

 

[uptown47]

I've checked the voltage drop / power usage and 4mm cable would be more than enough.

So a 15-20A load? Definitely no need for a CU for a few sockets and lights. Unless you go for the sensible idea of getting the supply to the sheds off the house CU altogether.

I think I would prefer to put a separate CU. I just wondered if I would need another CU for the other shed. Which it appears isn't the case.

I don't know about notification yet. I've not checked yet whether I need a building warrant for this work (after reading the great link from chivers it appears that if I don't need a building warrant then the work may not be notifiable - but again - I'll need to do a bit more reading on this).

Thanks again for your advice.

 

[Iggifer]

Burying SWA you normally run it deep enough to avoid a spade so at least 10 to 12 inches

500mm is a much better depth. So more like 20 inches according to google. You could easily penetrate 300mm with a decent spade in soft soil. 500 gives you room to lay the cable, backfill a bit, lay the tape and backfill completely. Nothing worse than cable below tape sticking out of the finished soil.