Help needed with electrical planning

[mhswardy]

Hi Guys
Newbie so go easy if I make elementary mistakes. I am an ex electrician and well aware of the requirements of Part P etc.

I am planning to convert a garage into a living room and adding an extension to it ( will obviously be applying for building regs.) Having looked at the rather quaint way my existing consumer unit and wiring was installed some 20 years ago I am wondering whether I will have to undergo major re-wiring or can get away with my planned solution. (I will have the work carried out by a qualified spark if/when my fund for the project come through)

The existing garage is at a lower level than most of the bungalow. The Consumer unit is located on an outside wall approx 4 ft high. Most of the existing cables (T &E) run (exposed) diagonally (approx 25 degrees) up to a height that allows them to be run through the roof void of the existing bungalow and distributed to the various rooms.

My issue is that if I convert the garage into a habitable living room then the wiring will not be in safe zones. I see two options. The first is to re-wire the whole house (not something I wish to undertake as Boss Lady has spent a fortune on decorating rooms with £100 per roll wallpaper !)

My second, preferred option is to build out (stud) the wall that contains the CU and diagonal wiring so that the wires are at least 60 mm deep. Will this be OK or will they need to be enclosed in steel.

The wiring for the new rooms will be on a separate CU with RCD protection etc

Any response would be appreciated

 

[ebee]

Personally I would like it deeper or protected by substantial metal plate (earthed) or a far greater distance.

However, 50mm is permitted by the regs so the choice is yours.

 

[PrenticeBoyofDerry]

Have you a picture you could upload?
There are number of options you have, some not as asthectically pleasing as others.

You could consider running the cable in metal conduit but this will alter the current carrying capacity of the cables.
These are the requirements

Untitled

• PrenticeBoyofDerry
• 16 Oct 2011
• 20

You will also need planning permission for change of use, if building controls are involved in the development (which they need to be) , why are you not taking on the electrical work yourself?
You can cover it all under one application, that's if it makes sense.

 

[holmslaw]

Just cover them with a minimum 3mm thick earthed steel plate. Don't chase them in +50mm deep, thats a hare brained idea dreamt up by some genius at the IET after a very heavy lunch.

 

[securespark]

Heavy on what?

 

[RMS]

The first is to re-wire the whole house (not something I wish to undertake as Boss Lady has spent a fortune on decorating rooms with £100 per roll wallpaper !)

Thats understandable.

My second, preferred option is to build out (stud) the wall that contains the CU and diagonal wiring so that the wires are at least 60 mm deep. Will this be OK or will they need to be enclosed in steel.

This makes sense and will be acceptable. Additional protection will not be required as you will have the cables >50mm in the wall.

 

[ban-all-sheds]

These are the requirements

Untitled

• PrenticeBoyofDerry
• 16 Oct 2011
• 20

Alternatively refer the OP to the Wiki //www.diynot.com/wiki/electrics:walls that being why it is there.

FGS.

 

[bernardgreen]

Just cover them with a minimum 3mm thick earthed steel plate.

Do you mean "earthed" or "bonded" steel plate ? Please be precise and do not confuse the OP

Don't chase them in +50mm deep, thats a hare brained idea dreamt up by some genius at the IET after a very heavy lunch.

Haven't you seen the EU ban on screws longer than 49 mm for use in domestic walls.

 

[holmslaw]

PS.

mhswardy - please bear in mind, when reading stuff from holmslaw, that he is on a mission to discredit the Wiring Regulations because he doesn't like them.

BAS go on to any average buidling site and you will find 100mm blockwork if you try and cut a +50mm chase the wall will probably fall down. Anyone reccomending +50mm deep chases is talking nonsense.

There are some regs that are nonsense and thats one of them.

Edit - added 'chase'

 

[holmslaw]

Just cover them with a minimum 3mm thick earthed steel plate.

Do you mean "earthed" or "bonded" steel plate ? Please be precise and do not confuse the OP

I meant earthed and bonded.

Don't chase them in +50mm deep, thats a hare brained idea dreamt up by some genius at the IET after a very heavy lunch.

Haven't you seen the EU ban on screws longer than 49 mm for use in domestic walls.

No I did'nt know about that, thanks

 

[ebee]

"Anyone reccomending +50mm deep chases is talking nonsense."

Often actually chasing 50mm maybe a bad idea as you rightly say.

Where do the regs ask you to "Chase them" that deep?

 

[holmslaw]

"Anyone reccomending +50mm deep chases is talking nonsense."

Often actually chasing 50mm maybe a bad idea as you rightly say.

Where do the regs ask you to "Chase them" that deep?

The regs don't ask you todo anything.

 

[ebee]

You said.

"Don't chase them in +50mm deep, thats a hare brained idea dreamt up by some genius at the IET after a very heavy lunch."

Now you say

"The regs don't ask you todo anything."

 

[ban-all-sheds]

BAS go on to any average buidling site and you will find 100mm blockwork if you try and cut a +50mm chase the wall will probably fall down. Anyone reccomending +50mm deep chases is talking nonsense.

Sorry - I hadn't realised that you'd made a quick dash from the Wallis and Futuna Islands to Cumberland to check the thickness of the OP's walls.

That was jolly good of you - must have cost you a fortune, but unnecessary, as he was not proposing to chase in order to get the cables deep enough anyway.

 

[ebee]

Holmsy Baby,
Am I being flippant ?.
Nobody mentioned chasing 50mm deep.
You could do and the brickwork might or might not be suitable to accept that.

Any method of achieving 50mm or more is acceptable in so far as the wiring regs are concerned, provide of course all other considerations are taking into account regarding existing brickwork etc and to what extent, if any, you might want to chase it.

But you appear to have made two assumptions here:-

1/ Chasing 50mm deep.
2/ The brickwork not being up to having such a deep chase.

The brickwork might be enough in this case although there is a good chance that it is not and you are quite correct to warn of such.

Other ways of achieving this 50mm deep are available such as over-boarding or the existing plaster on the brickwork might well be very deep, even 50mm or more - it does happen.

PS - when I say brickwork I do realise it might be stonework or something other than bricks too!

The regs state what is to be achieved not how