Power from Summerhouse to shed

[nick00]

No problem with the help! Hopefully things will improve soon and you can get the job done and a bit more freedome to manage your son.

Most electrical wiring systems are fairly simple in terms of underlying theory, but the Devil is in the Detail to do with safe and reliable operations which is why the wiring regulations are 500+ pages and not just a couple of basic points!

The 'wiring regs' BS7671 are not very readable as well as being a significant price (£95 for current 18th edition), but the IET also do a set of guidance notes to expand on the regs and to include other aspects from other standards such as building and fire regulations, access for the disabled, etc. If you do want a book to get a good overview of how electrical work should be approached in the UK and some of the not-so-obvious points, then the IET "Guidance Note 1: Selection & Erection" is as good a place to start as any.

I see it for sale on Amazon, etc, but I would generally go direct to the IET web store to be sure it was the real one! The IET ship by FedEx (or did last time I used them a month or so ago) so delivery is pretty fast and reliable for your money.

All the best!

OK, thanks a lot and maybe I'll get a copy of the book for some further reading. Pic of the trench attached and I have run the SWA out of the bottom of the summer house and clipped in in place inside, leaving a metre or so spare where it will be joined up to the consumer unit. I'll leave the hutch end so that whoever does the job can decide where they want it to go in.

OK, so I have one more question! Would it be possible to tee out of the armour with some more armour to run to some lights? I have some tall trees in the garden and it would be nice to uplight them but I don't really trust the solar lights that you can buy, plus then you need to put the solar panel somewhere that will get enough daylight.

I suppose I am imagining some kind of underground junction box, does that exist for this purpose, do you know? If so, what would you run it to, IP rated sockets on the bottom tree trunks or what?

Also, I assume there is load to consider - would I need to work out the load before I start adding stuff willy nilly? I would guess so.

Actually that's much more than one question!

Cheers,
Nick.

 

[pc1966]

Generally speaking lights take relatively little power so you should not have much of a loading issue in any case.

While you do get underground cable joint that is way too much cost & trouble for this, much simpler would be to take any other cable runs in to one of the places where the current cable terminates and join it there (or feed from a FCU) if you really need 240V.

But unless you really want serious levels of lighting I suspect you might be better to look at some low voltage lights (i.e. that run from a safe 12V supply or similar) where you have far less safety issues to consider and could get away with less cable protection, digging depth, etc, for feeding them as a result.

 

[nick00]

Generally speaking lights take relatively little power so you should not have much of a loading issue in any case.

While you do get underground cable joint that is way too much cost & trouble for this, much simpler would be to take any other cable runs in to one of the places where the current cable terminates and join it there (or feed from a FCU) if you really need 240V.

But unless you really want serious levels of lighting I suspect you might be better to look at some low voltage lights (i.e. that run from a safe 12V supply or similar) where you have far less safety issues to consider and could get away with less cable protection, digging depth, etc, for feeding them as a result.

OK, that makes sense.

How about if I take a feed from my existing sockets in the summer house and run it to an outside socket on the rear of the summer house, then plug the transformer for the lights in there? That's if you can get an outside socket that will be big enough to take a bulky transformer plug?

Thanks,
Nick.

 

[Midwest]

Pop the swa in some twinwall ducting.

 

[pc1966]

If you are looking at a bulky transformer-plug then I would say you ought to put it indoors, or have a small box added outside to shield the whole lot from the weather. Outdoor 13A sockets are generally fitted with covers that are designed to close on a normal sized plug to provide shielding from rain, etc, and you won't get that with a wall-wart supply inserted.

Depending on your garden layout it makes sense to put a suitable 13A socket & protection in a convenient place (either summer house or shed) and then run the 12V cable(s) out to the lights.

As Midwest suggests you can put in ducting for running cables underground. For SWA you don't need to - but it allows you to add/replace the cable later if you do (and it is not too windy/tight to pull through).

If you want to run normal wire underground, of the sort that 12V lights typically have, then it would be a big advantage in terms of protecting it from damage in the soil and allowing cables to be replaced later if needed. If you are using 12V (safe from shock) and it is not a critical function (decorated garden lights) then you can get away with less burial depth if you decide the risk of a gardening accident is acceptable compared to the time/effort of trenching in the first place.

Some ducting comes with a pull-string already routed through it, otherwise you might have to use a "fish tape" to pull through a small rope and then pull any heavier cable(s) with it. No, I have no idea why they are called fish tapes!

Fish Tapes | CEF

 

[Midwest]

Some manufactures of swa cable, so they product shouldn't be laid in waterlogged ground. Hence the ducting advice.

 

[pc1966]

Some manufactures of swa cable, so they product shouldn't be laid in waterlogged ground. Hence the ducting advice.

That is surprising! The stuff I have looked at (Doncaster Cables BS5467) seems OK for direct burial, etc. But if there is ever the need to replace or add to it, then ducting is an excellent investment!

In our case (project currently in limbo with lock-down) we were thinking of running some network cable in along side the main power SWA in overall 125mm duct, not that we need it now, but just in case we ever need it in the future. Some network cable has black harder UV-tolerant sheath so should be OK for the damp environment in the duct but would not survive being buried in stony ground.

 

[Midwest]

I've posted this link a few times now;

Electric Cables in Water?

Electric Cables in Water?

www.whyprysmian.co.uk

 

[pc1966]

Thanks for the link! I guess it comes down to the conditions you find the cable will be in but that is handy guidance to cite as well.

 

[nick00]

Sorry for the late reply, thanks, yes - that's what I thought, is there an alternative to bulky transformer plugs with 12V systems and would it be possible for me to alter the length of the cable if its too short for what I need?

Then again, I quite like the look of these Single External Spike GU10 Spot Black IP65 spots, but they are 240V, so how would I go about running wiring for these? I was under the impression that underground outside wiring should be armoured, but maybe something less substantial is okay for use with ducting? Or could the cable just be run over ground, so that its easy to see when out with the spade? So much to learn and so many questions! Its no wonder that you can't become an electrician overnight!

Thanks to both of you for your help.

Nick.

EDIT: P.S. The ground I am laying this stuff in is usually dry, it's tree covered and doesn't see much rain.

 

[pc1966]

Leaving wires exposed on the ground is a bad idea, not only is there a risk of damage when gardening, it is also a trip hazard and gives even more access to rodents, etc, which might chew the cable.

For direct burial you really ought to use SWA cable as it is the best protected, even then for very rocky ground you should sand-fill the trench around the cable to stop stones causing high local pressure and possible damage.

If you put in a duct you can put any cable in it really, but the duct ends should be sealed to keep vermin out, etc, and also when the cable does exit the duct it has to be suitable for the environment there.

A common cable that is OK for outside use is the 'HO7RN-F' tough rubber cable such as:

Superlec 3CORE 1.5MM 3183P H07RN-F EPR / PCP FLEXIBLE MAINS CABLE - EN60332-1-2

H07RN-F Cable is a non armoured flexible mains and control cable designed primarily as a trailing cable for use in the supply of energy for portable or mobile equipment.The cable is Ideal for use with transformer pumps, welders grinders, temporary lighting cable and feed cables to heavy mobile...

www.superlecdirect.com

That is a bit chunky for lights, overall diameter is around 12mm, but it is pretty tough stuff. Also it would fit some of the sealed junction boxes that are advertised below the light you linked to, for example:

16A Weatherproof Junction Box - IP68 | Knightsbridge (JB004)

You can power the lights simple from a 13A plug with a 3A fuse, or hard-wired in to a FCU. If you do put it on a dedicated switch then, while it is not essential, I would typically put it on a double-pole switch just so if it gets badly damaged you can isolate both L & N with the switch (as you would get from a socket or FCU).

Unless it is from an RCD that you don't need for other things. Basically if you only switch the L then you make it safe by switching off, but an N-E short can still trip the RCD and the single pole switch wont stop that.

Edit to add: Use LED bulbs - lower power and longer life so less risk of damaging the water seal when changing them!
[automerge]1587286720[/automerge]
Example of cable duct:

Underground Electric Power Cable Ducting Coil 32/40mm x 50m Black | Drainage Superstore®

Underground Electric Power Cable Ducting Coil 32/40mm x 50m Black from Naylor. (0707RC4050B). Order Helpline ☎ 01752 692 221

www.drainagesuperstore.co.uk

[automerge]1587288441[/automerge]
Other might have more opinion on the matter, but it seems this cable would be OK for direct burial (i.e. without expense of additional duct) if there is low risk of damage:

Superlec 3CORE 1.5MM NYY-J NON ARMOURED MAINS CABLE IEC60502-1

Please note: If you require advice on which cable to use, how and where to install it, it is recommended that you will need to contact the relevant qualified tradesperson for the job as the Superlec Direct Team are not qualified electricians.

www.superlecdirect.com

It is not intended to flex as I think it is single strand wires (like 1.5mm T&E), really it is more of a fixed power feed, but in your case that should be fine. It is not armoured, so no issues of needing special glands to earth the armour and so the 3-core version would be fine with those IP68 junction boxes.