Garage wiring, some background reading required

tlyons

Hi,

I'm looking at options to wire garage and little shed.
Shed will just have a 13amp socket and light.
Garage will have much bigger load
20-30Amps Compressor
16Amp Welder
Power tools,
Lights

Already got some advice from boards.ie and have the following basic idea
1. Armoured cable from house fuse box, on separate trip switch
2. in garage, a consumer unit with the following separate circuits feeding
a. Shed, light and socket
b. Garage, sockets
c. Garage, lights
d. Garage high load (compressor & Welder)

I have a certain amount of understanding of electrics but need much more before I start this project. eg Amp ratings for mm^2 cable, voltage drop over distance. Calculating reasonable ampage that the setup should be designed for. etc...

Any good websites or books to recommend?

I want to do the job right, hence the need to do the research

10-10-20

If you are specifically looking for reading matter, Maplin do some good guides based on the specifictions on residential wiring.

http://www.maplin.co.uk/Search.aspx?criteria=electrical%20book&source=15&SD=Y

mealone42

tlyons wrote: »

Hi,

I'm looking at options to wire garage and little shed.


I want to do the job right, hence the need to do the research

Get an electrician and then the job will be done right. QED

tlyons

mealone42 wrote: »

Get an electrician and then the job will be done right. QED

Where is the challenge? Seriously though I agree it needs to be done right and safely, your point has been noted.

I am currently running a compressor that is much lower spec than what the experts have recommended to me. Its running the tools that I require, the last test is actually spraying which is an other bucket of frogs for me to learn. However I have a front of a car to cut off and weld a new-ish one back on. Funny its the spraying in all this that freaks me.

Stoner

All i can say is that the load you require looks big, I know people operate garages off their domestic supply all the time, however I'd question the capability of a domestic supply taking care of your needs if you run the welder and the compressor at the some time. (+ cookers, electric shower etc)

steel conduit drops to 16amp sockets is always a good idea so i'd consider that. the welder and the compressor will need dedicated cable circuits, i'd use 4sq for the welder and 6sq for the compressor.
If you dont like the idea of steel conduit consider surface cleated SWA, I am assuming that the garage is already in place? and you cant recess the cables

You would need a 3 x 16 sq CU cable to feed the shed in the first place.

Your choice of switchgear will be important, I would not use a RCD here for power, just individual RCBOs.

Also you need to investigate if the welder can be used with an RCBO or does it simply require an MCB, if it does then put in a three pin industial socket and plugtop on the welder, this will prevent you from running something else off the welder circuit (if it has no RCD/RCBO protection)

Advice on getting an electrician +1

fishdog

I would agree with Stoner.

Steel conduit is a great idea, it will look alot better too.
I would use an IP rated distribution board (such as Hager). It will keep all of the dust and dirt out of the MCB's. Get one that is twice as big as you think you will need, this makes life alot easier.

Remember flourscent lights can be dangerous with rotating machinery!! (Strobe effect) This has caused alot of accidents in garages.

Get an experienced electrician +2

Also I think you will find that the welder will just keep tripping the RCD / RCBO due to its nature even if it has its own dedicated one. Therefore I would consider connecting it permanently so that it does not require an RCD / RCBO and having a local isolator for it. Although it is only rated at 16A I would feed it with a 6 or 10 square cable. This is because even a really small volt drop will cause a noticable drop in the power of your welder and a 16A welder does not sound that powerfull in the first place. I am not an experienced welder, but my friend is. I made up an extra heavy extension lead for him in the past and he told me how it made an enormous difference.



I think you need to look at the total loading i.e. house + garage. Have you an instanious shower ???? Electric hob ??? Think of the load of compressor, welder, power tools and house at the same time it may well blow your main fuse!!

tlyons

Cheers guys. Lots of food for thought here