shed power

[josh1e]

Hi,

I have laid a mains cable (13a flex) from a room in the house up into the loft, then down the outside of a wooden pannelled house (under the pannelling), and down into proper pipe designed to carry electrical wiring, this pipe is buried as our garden was landscaped recently, and goes to a shed. the pipework comes up into the bottom of the shed through the floor. Is this required to be certified, or is it okay as a diy job?

Inside the house, the cable plugs in to a normal socket, so is not hard wired to the house electrics in anyway. in the shed, an ip66 junction box splits the feed to a ip rated waterproof light switch / light, and then to ip rated waterproof sockets for a lawnmower etc.

I am not sure if it counts as a long extension lead, although could it be classed as hidden cable or hard wired because of the way i have routed it / mounted it in the shed?

thanks

 

[kkynaston]

This is not the way to do it at all i'm afraid.
Even though it is 'plugged in' it is a permanent installation and requires building control notification.

How long is the cable run, do you have RCD protection in the house?
Also as you have wired straight into a light switch you do not seem to have fused it down to protect the lights

What happens when the mrs wants to put the tumble drier & the freezer in the shed? (it always happens) Your flex will not be able to handle the extra load.

You really need to get a sparky in to give you and idea of what you need to put in.

Ideally you would run a submain from the house CU to a small garage CU with RCD protection. Then run your circuits from that. If you do it properly now you won't have the hassle later when you want to add the above items and a pond pump, power tools, pressure washer, etc etc

 

[josh1e]

Hi Kk.

thanks for the reply / advice.

the run is approx 25m including horizontal & vertical runs etc.

The flex used is the thicker stuff, not the cheap, nasty & thin stuff, its 2.5mm or thicker... I'll see if i can find the rest of the roll...

I understand your concern about washing machines & heavy appliances in there, but the shed will never have anything like that in there as it is used for storage only & almost full already, our kitchen happily houses those appliances already, so no concern there. Electric in the shed was an after thought & for convienience only. (i hate ponds, so pond pumps will also never happen!!)

the sockets in the house this extension is connected to has its own circuit / ring with its own 32a trip, the fusebox has 80a / 30ma rcd protection also. I've also checked this is part of the ring & not a spur.

If i wanted to rectify this what should i do to put me back within the law / regs, alternatively if i employed an electrician to put it right, would he need to run completely new cable from the fusebox on its own circuit to the shed or should he be able to just correct what i have done & then certify it?

thanks again,

 

[josh1e]

just re-reading part p, etc. i am unsure which applies

it states for example - electrical work in a shed is not notifiable. then it states lighting or sockets in a garden or wiring running across it is.

as i have a cable to the shed which runs under the garden, does that make it notifiable?

i understand getting a sparky in is the professional way to do it, although if it is not notifiable then i "should" be able to do the work? there are no exposed sockets / wiring / lights anywhere externally.

thanks

 

[ban-all-sheds]

our garden was landscaped recently,

Oh dear.

Is this required to be certified,

Yes.

or is it okay as a diy job?

No. Not because it's a DIY job, but because it's a cr@p one.

I am not sure if it counts as a long extension lead,

It doesn't.

although could it be classed as hidden cable or hard wired because of the way i have routed it / mounted it in the shed?

Yes.

the run is approx 25m including horizontal & vertical runs etc.

Did you work out what the voltage drop will be?

The flex used is the thicker stuff, not the cheap, nasty & thin stuff, its 2.5mm or thicker... I'll see if i can find the rest of the roll...

It's the conductor cross-sectional area which matters, not the overall size of the cable.

I understand your concern about washing machines & heavy appliances in there, but the shed will never have anything like that in there as it is used for storage only & almost full already, our kitchen happily houses those appliances already, so no concern there. Electric in the shed was an after thought & for convienience only. (i hate ponds, so pond pumps will also never happen!!)

And when the next occupant moves in?

If i wanted to rectify this what should i do to put me back within the law / regs,

Notify LABC and re-do it all properly, or get a registered electrician to re-do it all properly.

alternatively if i employed an electrician to put it right, would he need to run completely new cable from the fusebox on its own circuit to the shed

Yes.

or should he be able to just correct what i have done & then certify it?

No. i.e. correcting it will mean replacing the cable etc.

 

[big-all]

as a chippie my understanding is definatly notifiable as new works as a whole

replacement like for like ok and some minor alterarions

ooo there you are a slightly better answer by bas

 

[ban-all-sheds]

it states for example - electrical work in a shed is not notifiable. then it states lighting or sockets in a garden or wiring running across it is.

Had you moved in and there was already power to the shed you could have added sockets and lights in there without it being notifiable, but of course you would still have to comply with P1.

as i have a cable to the shed which runs under the garden, does that make it notifiable?

Yes.

i understand getting a sparky in is the professional way to do it, although if it is not notifiable then i "should" be able to do the work? there are no exposed sockets / wiring / lights anywhere externally.

You are free to do any work you like, from changing a light switch through to a complete rewire with outdoor power, lighting, fountains, swimming pool, sauna etc.

The issue here is not whether it's notifiable (which it is) but the fact that you've not done it properly. You've not considered the cable size regarding voltage drop and fault loop resistance, you've not used the right sort of cable and you've not installed the cable properly.

 

[josh1e]

thanks for the replies. i appreciate your clarifying what i've done wrong.

I understand 2.5mm t&e is sold as a measurement of the cores not the overall cable size, that was the same as i quoted for the flex. it was hedley & ellis 100m roll which we had previously used on a job & had enough left over. the electrician on the job didnt need it & said i could use it. It was way to thick to make up an extension lead so i considered it okay for this. If 2.5mm cable (core size) was wrong for this, can someone point me to the correct stuff please?

Does the installation for the shed have to come from the fusebox or can i install it as a fused spur going to a fusebox in the shed? then from that 2nd fusebox, a lighting ring & mains ring? if i start with fuseboxes does that then need to be done by an electrician or can i do it? i realise that as i have laid a cable / or a cable will be laid it is now notifiable..

even after reading parts of building regs & planning dept brochures, I am still slightly confused over what i can do & what i have to get a qualified electrician to do.

please bear in mind, that this is cable we have used professionaly and i believed to be adequate. from memory, when we bought it, there was a choice between armoured cable or this, as it was to be protected via external metal trunking, armoured wasnt required.

thanks

 

[mattylad]

Perhaps someone can suggest "how he should do this" rather than how carp the existing setup is

 

[2scoops0406]

It's been done to death on the forum, just look it up.

 

[bongos]

If you are burying a cable in the garden then you should be looking at using SWA.

The size of which you will have to calculate depending on what load you will be drawing at the shed. For a 20A load (you mention lights and a lawn mower) over 25m you would require at least 4mm SWA so that you do not go over the limit for lighting voltage drop.

This could be connected to a 16A MCB in your cosumer unit. Is your existing CU RCD protected?

But there are other things to take into account. Also if you are installing a cable in the garden then its better to future proof it and go for a larger size than you currently require. Maybe you will decide you like spending more and more time in the shed

 

[josh1e]

Hi & thanks for all the replies & information.

I am still looking for the original roll, i thought i had some left. 4mm seems alot thicker than i had anticipated, but i do understand why.

In trying to correct this, does it have to come from the fusebox or can i for example take a 2.5mm T&E run twice, put in an inline fuse within the house (for example next to where i connect these wires) and correct it that way? or would house cu to a cu in the shed & then run lighting / power circuits from there be the correct way to do it? (thats how i wired the previous shed, although it wasnt practical this time around for various reasons)

I ask because i dont know, so please go easy on me with the replies

Lastly, if it must be from the fusebox, am i right in thinking i cannot do that? i am allowed to install spurs etc, but not completely new circuits?

(oh & the cu does have rcb protection)

thanks
josh1e

 

[bongos]

In trying to correct this, does it have to come from the fusebox or can i for example take a 2.5mm T&E run twice, put in an inline fuse within the house (for example next to where i connect these wires) and correct it that way?

I'm not sure what you mean. Are you suggesting that you take 2 x 2.5mm feeds instaead of a 4mm feed? It's not really the best way to do things just to save some cash and it doesn't change the fact that for burying cable in the garden you will require SWA not PVC.

or would house cu to a cu in the shed & then run lighting / power circuits from there be the correct way to do it?

Yes. This is the best way to do it.

Lastly, if it must be from the fusebox, am i right in thinking i cannot do that? i am allowed to install spurs etc, but not completely new circuits?

If you notify the LABC before you start work you can do what you like. Whether you should do this work though is another thing

As already suggested, do some research on this site. There are loads and loads of shed questions which should give you an idea of what your different options are, whether the circuit will need RCD protection at the main CU or not and how to discriminate between RCD's if you end up using more than one, different earthing systems at your main supply etc etc... These points are all relevant when designing your shed supply.

 

[josh1e]

hi bongos

thanks for your help,

I am happy to run another adequately rated supply from the cu to cu in the shed. then to run 2 rings for lights / power from there. it is what i had originally done prior to getting the garden done

I need to check the route i use for laying this feed as the cu is on the front of the house & shed on the back, so dont want to run it through the wrong locations.

thanks again, great help ty.