'Borrowed' Neutral in Grid switch

[Bob23]

Hi, Fairly new! have a question if I may?

New build house.. 1.5swa wired off ring main (13amp s/spur) to garage > terminates at 20amp DP switch in garage.

garage has: lighting and power (interior/exterior light 1.0mm / 1x double socket.. actually wired in 2.5mm)

After the 20amp DP - Can I use a 3 plate grid switch (fuse unit for lighting, light for outside, light for inside) ? obviously the 13a socket will loop off the supply side of the fuse unit..

My concern is.. I'm joining the neutral of the lighting to the neutral off the sockets (I didn't realise the grid fuse wasn't double pole) however technically the grid is my 'garage consumer unit' with isolation on the 20amp DP in the garage, is this joining of the neutrals passable to current regs? I know it's not ideal but as long as it's a pass I'm happy.

Also, is wiring a garage in 2020 a thing with 1.5mm? or did plonkers build my house? I figured it was a standard 2.5mm feed from a 20a MCB into a 2-way consumer unit type of job??

 

[ProDave]

It's all one circuit so you are not borrowing a neutral.
 

To minimise junctions take socket feed straight from 20A DP isolator and a separate feed from 20A DP isolator to grid switch for lighting.

But who wired a garage feed in a new build in 1.5mm wants shooting.  You won't overload it since it's fed from a 13A FCU but it will be VERY limiting what you can feed from it.  I hope Welding is not your plan?  In a new build I would have expected at least a 6mm feed direct from it's own circuit at the CU and not sharing an rcd with the house circuits.  Yes built by numpties.

 

[kerching]

Yes built by numpties.

wired by cretins

signed off by morons

sold by estate agents

didn't realise the grid fuse wasn't double pole)

Seriously?

 

[Bob23]

What would really make you laugh is the spur in the house is four feet away from the consumer unit!?

I wouldn't of thought anyone would use 1.5mm as a supply to an outbuilding, but here we are! difficult to change as they then went and surfaced the drive. I did see one of the sparks 'He seemed to think it normal' maybe if they'd remembered to put a supply to the board with a 16/20 behind it, I might've got 2.5mm.

I wasn't planning on a tesla charger any time soon!

 

[Bob23]

Seriously?

Sadly, I've not wired anything for a while.. I wasn't intending using a grid - but my dual box exploded trying to put 20mm holes in.. The grid is technically redundant in the house (swapped for socket) as the kitchen units/wall measurements in the plan didn't allow for what's on the grid..

I guess trying to get 2-poles and a fuse into a modular is a fairly tall order!

 

[Murdoch]

Yes built by numpties.

wired by cretins

signed off by morons

sold by estate agents

Seriously?

All controlled by accountants maximising profits

 

[kerching]

All controlled by accountants maximising profits

I think you may have used far too many letters when spelling accountant

just saying

guess trying to get 2-poles and a fuse into a modular is a fairly tall order!

It actually read as ( to me anyway ) double Pole fuse, thus my snarky comment

 

[Sharpend]

Bob it may be that there is a duct which the cable is passed through, so replacing my not be that difficult. 

 

[Bob23]

Bob it may be that there is a duct which the cable is passed through, so replacing my not be that difficult. 

There is. It pokes out of the tarmac at the garage - so no real issue one end.. if it runs the full length of the cable will be a bit of a gamble! If the need arises I'll change it - getting back to the board is tricky as there's a cupboard, gas boiler and chipboard floor.

 

[UNG]

But who wired a garage feed in a new build in 1.5mm wants shooting. 

End of the day no 2.5 left so in goes the 1.5, seen it a few times in the past

 

[revjames]

Bite the bullet and do it properly in 6mm