Wiring small workshop

[8squared]

Hi all.

Just finished building myself a very small workshop which wasn't too hard considering it was my first big project and I have no previous building skills.

The issue I have is trying to wire it up for electricity, this is something I'm trying to read about but it's getting really confusing.

At the moment I run a 2 plug extension lead from the kitchen to my workshop, as its only a few feet away.

What I would like is to have the electricity from kitchen go to a fuse box then to my appliances and a few spare plug sockets.

Tools that would be permanently switched at the wall are...

Table saw, maitre saw, drill press, router, Hoover and 2 lights (on a dimmer switch)...

There would be maybe 2 or 3 spare sockets.

Any help in laymen terms as to what I need and how to do it would be great.

Thanks

 

[woodpig]

Up until about ten or twelve years ago you could have got away with doing it yourself but these days the local council really don't like you doing it. I can't quote the regs but suffice to say that even though I was more than capable of wiring up my own workshop I've recently had to pay a sparks to do it. I'm now waiting for a certificate to drop through my letterbox to say it's been properly installed by a qualified electrician. I saved a bit of cash though by mounting the sockets and light fittings myself and the sparks was happy to just wire them up. I also racked out the path and route for the armoured cable.

 

[flanajb]

If you feel competent to do the job then you can do the job yourself. Just pay your dues to the local council and do the work yourself under a building notice.

http://www.planningportal.gov.uk/permis ... electrics/

However, before applying I would be totally sure you are happy with what you need to do, as Building Control will want to be satisfied you are up to doing the job. Once you have done the work they will get some around to sign it off.

I wired my garage this way and was glad I did. Saved a few quid, and made sure the job was done well. Building control then sent around a certifier to check my work and sign it off.

First things to check.

1) Do you have a spare slot on the non RCD side of your consumer unit. Running to the RCD could cause your house to trip?
2) Is the main breaker a high enough amperage. Ours was 100 amps, so plenty of head way.

If 1 and 2 are ok. Then I would run a suitable sized amp rcd from the house CU into another smaller CU in the garage. You will need to calculate the size of the cable (armoured if under ground) using an on line tool. This will calculate the voltage drop for the length and what max Kw you want to have in the garage. You can then have a 16 amp lighting rcd and ring. And one or 2 32 amp socket rings.

Hope that helps

 

[8squared]

I am going to be doing it myself once I understand the technical side of things... but that's were my problem is, I start reading online about amps, kWh, different cables, voltage needed... drops etc etc and all I see is words, sort of feels like I'm trying to solve the enigma machine.

I know I should probably use an SVA cable from the in-house CU but how would I go about wiring it in ( if I can get to it from outside (issues with how house is built.

Once I've got power to shed again how do I install the wires and safely.

Most of what I've found online assumes you have some knowledge were as I have none and what to learn.

 

[RogerS]

Do you have a spare way in your CU? If not then you'll probably need a separate isolator/breaker thingie connected in via Henley blocks.

But TBH while I am all in favour of folks doing their own thing, you might be better off getting someone in to do the finer points ....such as terminating the armoured cable. How are you going to run it down to your workshop? Trench? Catenary wire?

 

[RobinBHM]

I expect most qualified electricians on this or other forums will tell you not to do it yourself, If you have no experience. The best compromise would be to find a helpful electrician to advise, set out the first fix and would allow you to do the donkey work yourself, then come back and do 2nd fix and test and certificate . I wouldn't install the work yourself first then try to get it certificated. There are so many regulations covering domestic wiring that you would find it hard to do everything so it is compliant. An electrician wont be keen certifying work retrospectively, so best to get one involved at the outset.

Terminating a SWA cable is awkward. It usually needs to be fitted to a metal box, so if your CU is plastic, I would suggest you might need to terminate to an adaptable metal box. I've found a plumbers pipe cutter useful for trimming the sheath and the wire of an SWA cable neatly so they acutally fit into the gland.

 

[Deejay]

Afternoon all

find a helpful electrician to advise, set out the first fix and would allow you to do the donkey work yourself, then come back and do 2nd fix and test and certificate

+1 Robin

You can get your own work tested and certified via the local authority, as Flanjab says, but it might cost you more than paying a spark to do the terminating and testing. I had some work done under building reg's in Devon, and the inspector advised me to do it through a registered spark. Ask the council what they would charge. If a spark does it, he should give you a copy of the test results and then register the job with building control, who will send you the certificate. If you sell the place, the buyer's solicitor will expect one.

Get your spark to size the cable feeding the shed. Bear in mind that you won't be using everything at the same time, but you might want to fit an extractor and perhaps a heater.

Most of the stuff you refer to would probably be OK on a normal domestic ring main. Don't skimp on the sockets. Think about a socket or two mounted in the roof, so you can plug things in without leads trailing on the floor. I'd run surface trunking for the cable. It looks tidy and protects the cable from damage.

Fit a bigger CU than you need. If you have a few spare ways, additional stuff is easier to fit.

The table saw might need a dedicated radial circuit with a different type of circuit breaker. If it comes with a standard three pin plug, it will probably be OK on the ring main. Have a look at the spec. for the machine and ask the spark.

I had a 160 square foot shed with four twin five foot flourescent tubes. If I needed extra light anywhere, I used a portable light. If your shed is 'very small', you might be OK with two. If you hang the fittings on chains and leave a bit of slack on the flex, you can move them if they aren't in the best place. Painting the inside white will help. I failed to find any hard information about lighting levels, so I went for the suck it and see approach.

Hope that helps

Cheers

Dave

 

[geordie]

when i did my shed i did the same as others ran all the cables fitted sockets,light, consumer unit basicly everything except connect it and a friend of a friend wired it in in a couple of hours for 40 beer tokens money well spent no head scratching or wondering if i did something wrong

Geordie

 

[n0legs]

I expect most qualified electricians on this or other forums will tell you not to do it yourself, If you have no experience. The best compromise would be to find a helpful electrician to advise, set out the first fix and would allow you to do the donkey work yourself, then come back and do 2nd fix and test and certificate . .

+2 for Robins advice.
Without doubt some of the most sensible advice regarding electricity on this forum =D>

 

[8squared]

Thanks for the sensible advice.

Can't do it on the cheap so will find a reasonably priced spark to advise, connect and test everything... but install things myself seems the best way to be happy and gave it done so everyone will be happy.


Will keep you posted on how I get on.

 

[woodpig]

As I said in post #2 I saved myself some money by putting up all the sockets and the lights. Mainly so they were where I wanted them but also to ensure it was done the way I wanted. I could quite easily have wired them up with the correct size T&E and terminating the armoured cable in a JB in the loft would not have been a problem for me. I was more worried that it was going to cost me more money to get someone to check and sign off my work. Doing it yourself is not popular with the council because you're not paying any tax on your own work! :lol: Thank god I don't need to get in a "Gutter inspector" to check the work I've just done on the shed...

 

[siggy_7]

I would suggest you'll want to do the following:

[*] Fit a new MCB to your existing consumer unit, which will supply all power to your workshop
[*] Run a cable from this MCB to your workshop, and connect up to a new consumer unit specifically for the workshop. For most applications a 6mm cable will suffice (this will give you 7.5kW of power on a 32 amp breaker), if you have big three phase stuff then you might want to consider a bigger breaker and a 10mm cable, but unless you're running industrial sized kit this is overkill
[*] Fit a new consumer unit to your workshop - I would suggest an 8-way to allow for expansion
[*] Run lighting and power sockets off of the new CU. Rings should be on a 32amp breaker with 2.5mm cable, spurs I would use 2.5mm cable but are limited to 16amps. For big single phase tools (table saws etc), run a dedicated circuit from the consumer unit on Type C MCBs (these allow more surge current on start-up, which is what big induction motors need) - if you run on 16amp Type B (common) MCBs you risk nuisance tripping with motors of greater than about 2kW.

As others have pointed out, some electrical work is notifiable under Part P of the building regs. This includes all consumer unit work - I would suggest running (but not connecting) the cable from the house to the new CU, and running all the cabling in the workshop to the new CU for your electrician to connect. Find yourself a Part P registered electrician beforehand who's happy to work on this basis though (search for small independents who will be much more friendly to this sort of work) and have a chat with him before you get materials/start work about your plans. My father in law recently did his workshop this way - you'll save yourself a couple of hundred quid and have the wiring precisely to your liking this way.

 

[RogerS]

Good points, siggy. If he does't have a spare way in his CU then he'll have to use Henley blocks and a separate breaker/fuse (which his electrician can advise on).

Also worthwhile considering an emergency light that comes on in the event of a power cut. Nothing like having a 'brown trouser' moment when you're ripping on the table saw and the lights go out. 'Now where is that spinning sharp thing?'

 

[dejaa]

From your own comments I would say get a professional qualified electrician.

As others have said, you can do it yourself, and then get the building inspector to sign it off. BUT, unless you actually know exactly what you are doing without having to read a dozen books, you're unlikely to complete the task to their satisfaction.

David