power to garden office

[charmalacious]

hi all, yr advice wld be welcomed:

I want to run power to my outside office (about 15 metres from back of house) to provide 4 or 5 sockets, panel (or underfloor) heating, lighting and security system. I have armoured cable for external run and plenty of 2.5 T&E for inside. I prefer to run supply back to CU rather than spur off the ring. My queries are:

1) How to connect 2.5 cable to extg CU and what rating breaker to use? (there is 1 blanked off spare place)
2) To avoid lengthy cable run around skirting and architraves etc. is it ok to channel 2.5 T&E into the floor screed (which will then be floor tiled over)?
3) Is it good practice/safe to pin the armoured cable to a timber fence (about 250mm from topsoil) or is it best to bury it in protective conduit?
4) Supply inside office to go into a sub-CU (such as the MEM memera 2000). What rating breakers do you recommend for power and lighting circuits?

sorry for long-winded qu's but they've been bugging me for ages.

cheers

 

[2scoops0406]

I'd get and electrician in, it's notifiable work for starters.

 

[davy_owen_88]

1) How to connect 2.5 cable to extg CU and what rating breaker to use? (there is 1 blanked off spare place)

I'd run 4mm² SWA atleast. 2.5mm² is only sufficient for a 20A MCB.

2) To avoid lengthy cable run around skirting and architraves etc. is it ok to channel 2.5 T&E into the floor screed (which will then be floor tiled over)?

The regs say that the cable must not be damaged by the intended use of the floor, and that the cable should be deep enough to prevent damage by the floors fixings.

Make sure you run a duct for the buried cables so they can be replaced/upgraded in the future. Bury the duct atleast 50mm deep, and continue the SWA through the duct for added mechanical protection.

3) Is it good practice/safe to pin the armoured cable to a timber fence (about 250mm from topsoil) or is it best to bury it in protective conduit?

It isn't a good idea to attach cables to fences, if the fence falls down, the cable will come with it.

Bury the SWA 400mm deep, backfill about 3/4 the lay warning tape. Installing a duct is a good idea for future upgrades etc.

4) Supply inside office to go into a sub-CU (such as the MEM memera 2000). What rating breakers do you recommend for power and lighting circuits?

If you are sticking with 2.5mm² SWA, then your MD must be <20A. I would fit a 16A MCB for the sockets, and 6A for the lights. Don't forget 30mA RCD protection for the sockets.

What earthing arrangement do you have? Remember that this work is notifiable in England and Wales, and must be notified BEFORE you start.

 

[charmalacious]

Thanx guys 4 advice. will review my works, or if i bottle it, i'll have to rope in one of the site sparkies.



cheers

 

[2scoops0406]

To be legal you must inform your LABC before you do anything. That's the point.