# Running power to my shed, but trying to avoid a big trench



## m1ke_a (22 Feb 2016)

My shed is at the bottom of our garden and is approx 25m from the house. 15m is garden, the remainder is paved patio which is one two levels, which has about 1m of height gain through the patio.

I've been putting off hard wiring the shed for too long but do really need to bite the bullet. I already have fluo lights installed and will eventually run 6 double sockets internally on two separate ring mains back to a dedicated CU in the shed. I'm fairly happy with the shed wiring design, it's just the wee matter of getting a cable back to the house..........

I will get a registered sparks to OK the design, install and commission it up etc but I do want to do as much of the manual labour as poss to save cost.

The neatest way is to bury the (SWA) cable but this will take the most work. Pinning the cable around the house perimeter is probably the easiest option but I'm looking at 10mm swa and I'm not sure this'll cope with bending round 90' corners?

Anyone any other ideas on alternate approaches?

TIA


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## Ali (22 Feb 2016)

I have a similar problem in planning to run power to my shed this summer. another option is a overhead cable run - it might not be pretty but can be effective.


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## m1ke_a (22 Feb 2016)

Ali":fms8vt6p said:


> I have a similar problem in planning to run power to my shed this summer. another option is a overhead cable run - it might not be pretty but can be effective.



Yeah a friend has suggested this but it'll probably need 2 or 3 tall poles and I'm not sure that's going to work with the neighbours :|


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## biskit (22 Feb 2016)

Same with my shed. 25 years ago I ran a cooker size cable in any size tube I had (waste pipe, rainwater pipe etc) under ground. Now I'm using the shed as my workshop I could do with a proper cable :? Don't want to run it above ground, it's going to be hard lifting flagstones and relaying them. :x let us know how you go with yours.


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## Wuffles (22 Feb 2016)

biskit":3j2qxu39 said:


> Same with my shed. 25 years ago I ran a cooker size cable in any size tube I had (waste pipe, rainwater pipe etc) under ground. Now I'm using the shed as my workshop I could do with a proper cable :? Don't want to run it above ground, it's going to be hard lifting flagstones and relaying them. :x let us know how you go with yours.



In your situation, couldn't you just connect a new wire to the old one (LOADS of tape and cable ties etc) and drag it through if the pipework you used before was loose enough?

It's a risk mind you, but certainly worth a punt before lifting flagstones or running it overhead.


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## biskit (22 Feb 2016)

Wuffles":1d7irkiw said:


> biskit":1d7irkiw said:
> 
> 
> > Same with my shed. 25 years ago I ran a cooker size cable in any size tube I had (waste pipe, rainwater pipe etc) under ground. Now I'm using the shed as my workshop I could do with a proper cable :? Don't want to run it above ground, it's going to be hard lifting flagstones and relaying them. :x let us know how you go with yours.
> ...


Yeah I know what your saying :roll: I'm worried that the pipes being of different sizes things'll get all hooked up. I'll have to give it a go when it gets warmer. (hammer) ccasion5:


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## Rorschach (22 Feb 2016)

Wuffles":3uxtot3v said:


> biskit":3uxtot3v said:
> 
> 
> > Same with my shed. 25 years ago I ran a cooker size cable in any size tube I had (waste pipe, rainwater pipe etc) under ground. Now I'm using the shed as my workshop I could do with a proper cable :? Don't want to run it above ground, it's going to be hard lifting flagstones and relaying them. :x let us know how you go with yours.
> ...




I would use the old cable to pull through a really long piece of rope (at least twice the length of the pipe plus a bit) then attach the new cable to the middle of the rope and pull through, that way if the cable comes loose from the rope you still have the rope in the pipe and you can try again as many times as needed.


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## Jacob (22 Feb 2016)

I'd go for it and do a proper job with a large (enough for future alterations) diameter conduit. If you want to do it on the cheap just have an extension cable over the ground.


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## siggy_7 (22 Feb 2016)

Trenchless cable/impact moling?

Sent from my SM-N910F using Tapatalk


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## Jacob (22 Feb 2016)

siggy_7":37wum5cl said:


> Trenchless cable/impact moling?
> 
> Sent from my SM-N910F using Tapatalk


Had to look it up https://www.youtube.com/watch?v=glpsaCSvZsI
Brilliant but perhaps OTT for a mere 25 yards? 
I've seen similar thing with a tractor ploughing/pulling in a pipe or cable which works fine until you hit a big stone, bedrock, next doors drain, water pipe or power cable.
Better to get in a mini digger and a youth IMHO. or just a youth, pick n shovel and barrow.


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## cammy9r (22 Feb 2016)

Hi, is the cable going to be run near a fence or hedge. If so just clip it to the fence. If there is a hedge I think you can hammer in small fence posts and clip to them. Im sure the swa will bend around a right angle with a small radius left in the cable. I think that is your only options really other than the trench.
Jacob, I cant see many youths of today willing to swing a pick or use a shovel, unless you can get them an I-pick or a touch screen shovel with texting. :roll:


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## Bm101 (22 Feb 2016)

I have armoured cable running power down the garden to the shed, its currently lying on the ground along the base of the fence. Without going into needless detail it needs to swap to the other boundary. When I get round to it, I'm just going to disconnect from the shed, drag it all out and reroute it down the other side of the garden and secure it to the fence posts using appropriate fixings. I know where it it is, it's less of a hazard than burying in the beds and it saves me digging a straight trench though my lawn to comply with electrical regs. The wire is maybe just over half inch thick but you can bend it round 90' on a slight curve. Personally Id rather it was visible and away from any form of spade in my Mrs hands (shes the gardener). I'll even leave a little slack in between each fixing in case there's a freak storm that brings the fence posts down. Not suitable for a public area but this is my back garden.


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## n0legs (22 Feb 2016)

Two 4m poles, a nice tight catenary wire and sent it overhead.


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## NazNomad (22 Feb 2016)

I have an armoured cable running inside a length of blue alkathene water pipe, buried where it could be and clipped to the fence where it couldn't. 

It won't win any awards, but it's safe from weather/damage.


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## defsdoor (22 Feb 2016)

Could you run power cables down a series of scaffold poles connected with normal inline scaffold connectors ?

Might make a handy hand rail or just unobstrusively attached to boundary fence ?

Thinking of something similar for my run.


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## oakfield (23 Feb 2016)

As mentioned above, impact moleing would be a good option. 
My dad had a business doing this. 
Dig a hole at each end, put mole in and aim it, hopefully it will pop out in the hole up to 25m away. 
He also has a directional mole which can do 100m and you can control its direction along the way.


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## Eric The Viking (23 Feb 2016)

It's tempting to run several cables along the same round conduit. This isn't a bad idea as such, but over that distance, I'd make sure the draw rope was braided rather than laid (twisted). Otherwise cables and ropes, especially if they're quite different diameters or construction, tend to twist around each other in the duct and suddenly pulling isn't so much fun! 

Back in the days of telephones with dials, the GPO/BT used to use salt-glazed ductwork with IIRC nine or twelve 4" pipes cast together as a set, and they used to have lots of problems in this regard. 

Also, if you can make sure the duct terminates well above ground at each end, and ideally with no joints (difficult over that run, possibly), pulling things through will be a lot easier and there's little chance of water getting into the duct. 

I only have a very short run here, so I used a "U" of 2" yellow gas pipe (blagged from some gas men working in the road), continuing right up the garage wall inside, almost to the back of the distribution board, and similarly inside the house. I laid in CAT5 as well as power, but it should've been CAT6 really, because of proximity to the power cable. If I ever do swap it out, it should be a fairly easy job.

It is a long time since I last buried big armoured cable, but IIRC, the "buried cable" tape and the concrete warning slabs were both expensive. We went for cast concrete capping stones (for 1/2-brick walls) instead, and I think we blagged some tape to put on top. Possible cable damage is the reason for the isolating switch and (big) fuse back at the property's main fuse board.


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## Halo Jones (23 Feb 2016)

I am just about to finally put some proper power to my shed - using my extension cable starting the saw or dust extractor puts the lights out for a few seconds and it just really isn't safe!

One comment is that SWA cannot be pinned to a fence or a hedge - it needs to be a "permanent structure" like a brick wall. The sparky might not be able to pass it if the cable is not appropriately routed.

Good luck - I am looking forward to having proper electrics!


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## DTR (23 Feb 2016)

Bm101":1fwkrnth said:


> I have armoured cable running power down the garden to the shed, its currently lying on the ground along the base of the fence. ............. I know where it it is, it's less of a hazard than burying in the beds and it saves me digging a straight trench though my lawn to comply with electrical regs. .............. *Personally Id rather it was visible and away from any form of spade in my Mrs hands (shes the gardener).* I'll even leave a little slack in between each fixing in case there's a freak storm that brings the fence posts down. Not suitable for a public area but this is my back garden.



I'm in the exact same situation. In my line of work we get a lot of damaged cables, and you can almost guarantee that a mile-long cable will get damaged on the 10' bit that's in the ground. At least above ground it's easy to find and repair. 

Not that I'm suggesting anyone ignores the regs, etc etc


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## Setch (23 Feb 2016)

If you come up with a solution, keep it to yourself - I dug a trench about three times in heavy clay, as bad weather kept filling it back in!

I've got 40mm waste pipe buried in the same trench with a pull string, ready to run some cat 5, CCTV leads and a doorbell/phone extension. Getting under the brick flower bed which delineates a 2 foot change in level was fun! I used a bit of downpipe fitted with a T-handle to bore down at 45 degrees, like a cheese taster!


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## Eric The Viking (23 Feb 2016)

Setch":fw3w9azg said:


> I've got 40mm waste pipe buried in the same trench with a pull string, ready to run some cat 5, CCTV leads and a doorbell/phone extension. Getting under the brick flower bed which delineates a 2 foot change in level was fun! I used a bit of downpipe fitted with a T-handle to bore down at 45 degrees, like a cheese taster!



Clever stuff!

As I said though, use braided draw-tape (rope/string) or be prepared to have a lot of tangling up going on. And try as much as poss to unroll off a cable drum, rather than pull off the side of the drum - anything that gets twists out before you send it into the duct. 

I'd pull at least two at once to start with, too, as that reduces the risk of twisting up.


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## jackjohnsonuk (23 Feb 2016)

How about some pictures of the problem?
Theoretically a 25mm2 external diameter cable should have a a bend over about 450mm(ish) based on some old rules of thumb - So probably wouldn't stick tight enough to the building to be viable


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## AJB Temple (23 Feb 2016)

Why can't armoured be attached to a fence? 

British rail near us have just run about 100m of armoured (several lots) on brackets above ground in one of their car parks. It is on the public parking side. 

DIY sheds frequently run cables in exposed trunking trays. The new Notcutts garden centre and restaurant near Tunbridge Wells is largely cabled this way. 

My Part P electrician has just passed 4mm cable to an outbuilding that is mostly secured to a wire fence. I didn't install it (was done a few years ago by former owner) but he did not feel it was either unsafe or breached regs. It is after all armoured. There are numerous guidelines but not much of it seems to be enshrined in law. The key thing is not to do things that are unsafe. A well routed visible cable above ground may be safer than an invisible cable underground in some circumstances?


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## Bm101 (23 Feb 2016)

Don't know if it would work but I was just wondering about pushing armoured cable through pipes. Had a thought that maybe you could cut a cross in a tennis ball, shove the cable end into it and duct tape it up. Your ball acts as a buffer to any pipe joins etc that could catch a cable end. Bit similar to the old wheeled drain rods. Obviously it's only got a chance of working with armoured or heavy duty cable. Just a thought.


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## MusicMan (23 Feb 2016)

Just a point - the armoured cable required is very expensive. So even if you can bend it to the radius needed, it's going to be costly to take a more devious route than the shortest.

Keith


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## AJB Temple (24 Feb 2016)

For the short runs contemplated the differential cost of armoured is small. It is readily available on line. I just (yesterday) bought 120 metres of 16mm 3 core which came to £450 delivered including VAT. This is very heavy cable and we are only looking at £3.75 a metre inc. (you will pay more for shorter lengths but not massively more). An extra few metres will be irrelevant. It would have been £160 for 4mm 3 core armoured which will be sufficient in many cases with low voltage drop and not much demand. On-line prices vary by as much as double. Shop around.


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## Racers (24 Feb 2016)

Bm101":i0hnafw9 said:


> Don't know if it would work but I was just wondering about pushing armoured cable through pipes. Had a thought that maybe you could cut a cross in a tennis ball, shove the cable end into it and duct tape it up. Your ball acts as a buffer to any pipe joins etc that could catch a cable end. Bit similar to the old wheeled drain rods. Obviously it's only got a chance of working with armoured or heavy duty cable. Just a thought.




Pushing cables doesn't work the friction between the cable and duct increases as you push and the cable kinks and rubs against the sides, pulling will straighten the cable reducing the friction.

Pete


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## Wuffles (24 Feb 2016)

Racers":1bmeqpqd said:


> Bm101":1bmeqpqd said:
> 
> 
> > Don't know if it would work but I was just wondering about pushing armoured cable through pipes. Had a thought that maybe you could cut a cross in a tennis ball, shove the cable end into it and duct tape it up. Your ball acts as a buffer to any pipe joins etc that could catch a cable end. Bit similar to the old wheeled drain rods. Obviously it's only got a chance of working with armoured or heavy duty cable. Just a thought.
> ...



Unless you can put a wave into the pipe that's enclosing the wire, which in this instance you can't. For reference, when trying to get a wire into some conduit, pushing, as you pointed out, it'll fail pretty quickly as it just jams.

However, fix one end of the conduit, with a brick or something, pull it taught and put a sideways wave into it, it eats the cable up and pulls itself through.

Just in case that was of any use to anyone ever, thought I'd leave it here.

Try it, it's fun. I do it all the time when trying to get cat5 cable to outbuildings at my place. You know, it's a hobby and I'm not hurting anyone.


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## Racers (24 Feb 2016)

You can blow string down with a compressor, or rope with a bigger compressor1

Pete


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## Wuffles (24 Feb 2016)

Racers":393q9m3y said:


> You can blow string down with a compressor, or rope with a bigger compressor1
> 
> Pete



Did that with a ping pong ball once on the end of some thin gauge rope. Worked a charm.


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## woodshavings (26 Feb 2016)

I have armoured cable clipped to the garden fence to the 'shop.
John


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## m1ke_a (28 Feb 2016)

Thanks for the inputs guys.

Have had 3 sparks out to price up the work. Interesting to get different interpretations from "yeah it's your garden, you can do what you like and I'll just bung a MCB in the house CU" to the more considered "a switched fuse at the house end would be one option", "have you thought about inserting a small piece of conduit between the front door frame for future?" and "BTW the new amendment 3 regs may mean some design tweaks"

I'm definitely leaning towards the two who spent more time discussing the options and pointing out little details!

I was initially leaning towards a 40a total load and using 10mm SWA. One of the sparks thought that pretty high and two said 10mm is going to be fun to work with!

Shed has 3 fluo lights and the maximum I'd be running in there is a 1/2" table router, bandsaw, circ saw, workshop vac, some chargers and an oil rad. Obviously only the lights, vac and one tool at a time would be in operation so the continuous load wouldn't be too high (would it?)

According to http://tinyurl.com/zs5ulrk 40m of 3 core 6mm SWA = 7000w / 30.4A

Have since come across reels of flex ducting - http://tinyurl.com/jn3j8zr so that covers protecting the cable (and thanks for the tips about pulling cable).

On the patio, I have to cross a foul drain, I'll be going alongside out incoming water main somewhere and could also cross a bit of the gas main so I'd rather not try moles or mechanical digging! - The gas board got their mole stuck when they renewed the gas and had to close part of the main road to dig it out! :lol:


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