Garage wiring help.

[Dani99]

Good evening All,

I'm after some advice / help on my garage wiring. At present I have a large double garage with just two solitary double sockets! I'm after turning half of my garage real man cave ia sort of spray booth and the other half into a workshop / parking.

The current sockets are part of the kitchen ring main so would ideally like to install a new consumer unit in the garage or install an addition ring to my main consumer unit.

I rewired my old home so confident (Had it checked and consumer unit wired up and signed off after running the wires) but would just like a little guidance to my best option.

My question is.

• What would be the best option? Pull from my current consumer unit (Plenty of blank spaced in existing unit) or install an additional one into my garage? I'm after running 3/4 sockets in various places but would potentially pull 4-5KW (High estimate) with the welder, heater ect.
• What would be the best size cabling to use 2.5mm is what ive got spare.
• If I was to install an additional consumer unit would 6mm Armoured cabling be required even with the close proximity to the main unit (wold roughly be 7m apart)

Id ideally like to do the install myself and have it checked / signed off on completion.

Thanks all..!

 

[ericmark]

If you want to do it legal then DIY is an expensive route, if you want to break the law, may be you should not be asking! There are ways to kid your self it's OK, but new circuit needs notifying and third party inspectors are not much cheaper than going to council and either way leaves you without an installation certificate. Also you have to enrol the tester before you start, not when complete so he will answer the question.

I would use 2.5 mm² cable as larger cable becomes a problem to terminate in some sockets. As to cable protection be it conduit or SWA you need to assess the risk, with heavy engines and the like one could trap twin and earth and cause damage, I have seen where conduit is used 5 foot to socket but not over 5 foot as there will not be anything at that height likely to cause damage.

There is a reason why we sign to say we have.
1) Designed.
2) Installed.
3) Inspected and tested.
In some cases with three separate signatures, you can't ask anyone to remotely design what you want to install. Either you have the skill or you don't. There are points where you can ask some one what they think, for example all RCBO or RCD and if RCBO if two pole or single pole switching, but you can't expect some one else to do the lot.

As an electrician I still use scheme member electricians for anything requiring registering, yes I could DIY but the LABC charges are so high, just not worth it.

 

[ban-all-sheds]

... spray booth ...

Are you familiar with the regulations which apply to explosive atmospheres?

What would be the best option?

Using an electrician. One with the necessary skills for explosive atmospheres.

... welder ...

You'll need permission from your DNO for that.

What would be the best size cabling to use

The size(s) your electrician determines are necessary when he designs the circuits.

2.5mm is what ive got spare.

That is not the way to determine what size(s) are necessary.

If I was to install an additional consumer unit would 6mm Armoured cabling be required even with the close proximity to the main unit (wold roughly be 7m apart)

Why do you think that distance is a relevant factor?

Id ideally like to do the install myself and have it checked / signed off on completion.

It doesn't work like that.

 

[John D v2.0]

Why do you think that distance is a relevant factor?
.

Volt drop - if it's too far away you'd exceed the volt drop and therefore need a smaller protective device or thicker cable.

 

[Risteard]

a smaller protective device or thicker cable.

A protective device is not used to control the load!

 

[deadshort]

But it does

DS

 

[ban-all-sheds]

Volt drop - if it's too far away you'd exceed the volt drop and therefore need a smaller protective device or thicker cable.

I thought the subject of his question was the cable type, not size.

 

[ban-all-sheds]

But it does

But it shouldn't.

 

[John D v2.0]

A protective device is not used to control the load!

Yes good point I got the logic backwards - the volt drop is calculated from the rating of the circuit, but if down sizing the protective device would cause an overload then we're not in a better situation. If that meant the op couldn't use their welder or whatever then the circuit wouldn't be designed for their use.
So the circuit either needs to be restricted in what can be connected or thicker cable.

And bas you're right it does seem like the op was deciding the cable type based on the distance. Although distance can matter, since for a short distance a catenary suspended cable could be used but for longer distances not so much.

 

[flameport]

Id ideally like to do the install myself and have it checked / signed off on completion.

If you really want that, the options are:
1. Contact the building control department of your local authority and find out exactly what they want in the form of testing, inspection and if an installation certificate is required, then submit plans / building notice and pay whatever their fee is which may include them arranging inspections/tests or getting some electrician or similar person to do that.
Then do the work ensuring you comply with whatever they wanted.
2. As 1, but using a third party certifier - however there are very few of them and may well cost as much as the building control route.

Doing the work first and having it inspected later is not an option - notification is required first, as is establishing exactly what building control require.

There is a route for notification after the fact called regularisation, but is costs far more then doing it properly and as inspection will be required won't be of much use if cables have already been concealed in walls/floors/ceilings. Even less use if an inspection reveals that some or all of it has been done incorrectly, as it will then have to be done again.

The only other option is for electricians who are members of certain schemes - they can notify their own work through the scheme, which is cheaper if doing significant amounts of work each year - individual notification is only a few pounds but there are substantial annual fees and other requirements to belong to the scheme.
However this is only for work they do themselves, and therefore of no use for work done by others.