Electrical question, maybe a daft one...

[Mark M]

Im nearly finished landscaping the garden and the next thing Im looking to do is some lighting and sockets in. I will be getting an electrician in to do most of the work but depending on cost I might need to do some of the donkey work myself which leads me to a question...

The gardenis fairly large and I'd like some power at the very back but how does the wiring work for it? The fuse box (has plenty spare "slots" to use) is in the garage which backs onto the garden so no issues there and the furthest away socket will be about 30 meters so do I need 2 lengths of armoured cable to complete the ring main (eg send and return) or is there something clever you can do to get around this?

 

[MassiveJim]

my shed is on a fused spur (so no return line)
I don't think most people extend the ring main, unless your going to be running a lot of power hungry devices off the extra sockets ?

 

[Mark M]

Nothing massive, leaf blower once a year will be the most power hungry item I would suspect.

So from the fuse box you would wire in a fused spur and then straight back to the fuse box then from the spur run the armoured cable?

 

[Mercenary Keyboard Warrior]

Doesn't even have to back to the fuse box, its a nicer solution for sure but it can simply be a spur off the ring
If you spur off the ring you do probably want a switch though so you can isolate, for example when you go on holiday or if there was an issue with the line as you would have the whole of that circuit down without a switch to isolate it

 

[robj20]

If you spur off a ring use 6mm min. You can keep the 32amp mcb then.
Best way would be to add a dedicated radial in something decent like 6mm with a 38a mcb, or 10mm with a 52a mcb. No need for armoured just stick it in some conduit suitable for the purpose.

 

[Mark M]

Thanks for the replies.

Doesn't even have to back to the fuse box, its a nicer solution for sure but it can simply be a spur off the ring
If you spur off the ring you do probably want a switch though so you can isolate, for example when you go on holiday or if there was an issue with the line as you would have the whole of that circuit down without a switch to isolate it

I thought about spurring off am existing ring but then thought with it being outside it would be better to have it on its own? Plus if there was an issue I might just be able to flick that breaker off and the rest of the house could be unaffected.

If you spur off a ring use 6mm min. You can keep the 32amp mcb then.
Best way would be to add a dedicated radial in something decent like 6mm with a 38a mcb, or 10mm with a 52a mcb. No need for armoured just stick it in some conduit suitable for the purpose.

What type of cable would I use if not armoured? Just stardard twin and earth? Would the cost of the normal cable plus conduit not come to the same as the armoured? FYI the bulk of the run will be along the fence and not underground.

Another daft question, do I need an earth cable?

 

[Mercenary Keyboard Warrior]

Thanks for the replies.



I thought about spurring off am existing ring but then thought with it being outside it would be better to have it on its own? Plus if there was an issue I might just be able to flick that breaker off and the rest of the house could be unaffected.



What type of cable would I use if not armoured? Just stardard twin and earth? Would the cost of the normal cable plus conduit not come to the same as the armoured? FYI the bulk of the run will be along the fence and not underground.

Another daft question, do I need an earth cable?

Thats why you put a switch in it so you can isolate from the rest of that ring if required.

Normally armoured is 3 core, plus its good practice to earth the armour as well. Its not always done though some sparks don't seem to do it.

 

[a1ex2001]

If you can I'd put it on it's own circuit off the fuse board which as you say would be a simple connection to a fused spur and then back to the fuse box.

 

[Adam_151]

Quite a bit of iffy advice here!

If the the board is nearby and its easy enough to get back to and it has free ways, then makes sense to go back to it it IMHO, No need for a ring, a radial circuit would be more suited, no need for a fused spur either if coming straight off the board (you'd have one if you came off the ring though), although you might wish to have a double pole isolator instead (The MCB only isolates live, but a neutral to earth fault will still trip an RCD with it off)

You can't just come off the ring with a chain of spurs in 6mm without a fused spur

You must have 30mA RCD protection
While armoured isn't the only option, because you need a wiring system surrounded by earthed metal, its the only practical one, plastic conduit isn't suitable, MICC will be a lot dearer than SWA both to buy and have terminated.

SWA *must* have the armouring earthed (its not just good pratice, its a requirement)

 

[MassiveJim]

Quite a bit of iffy advice here!

If the the board is nearby and its easy enough to get back to and it has free ways, then makes sense to go back to it it IMHO, No need for a ring, a radial circuit would be more suited, no need for a fused spur either if coming straight off the board (you'd have one if you came off the ring though), although you might wish to have a double pole isolator instead (The MCB only isolates live, but a neutral to earth fault will still trip an RCD with it off)

You can't just come off the ring with a chain of spurs in 6mm without a fused spur

You must have 30mA RCD protection
While armoured isn't the only option, because you need a wiring system surrounded by earthed metal, its the only practical one, plastic conduit isn't suitable, MICC will be a lot dearer than SWA both to buy and have terminated.

SWA *must* have the armouring earthed (its not just good pratice, its a requirement)

This is the advice I would follow