Garden Lights + Power ... Which SWA Cable / How Many Cores?

[Tuttle]

I need to supply power to a couple of garden lights and a 13A socket in a longish garden.

The requirements I've been given so far are a bit vague - the socket needs to go at the end of the garden, the lights will probably go somewhere along the side of the garden, and I'm assuming that they will want to switch the lights on/off from the house. I don't know much more than that at the moment.

I plan to run SWA from the the consumer unit (a recent board with RCBO's) into the garden. The guy they've got landscaping their garden will dig the trench and bury the cable, they just want me to specify the cable at the moment.

I guess the easiest solution may be to run two separate cables, one for lights and one for power, i.e. two 3-core SWA cables. It would be nice to be able to use just one SWA cable if possible though, but I not sure how many cores I would need.

My first thought was 5-core SWA to give L+N for power, L+N for lights and a CPC common to both power and lights. But 5-core SWA doesn't seem to be that common - mostly I've seen 2, 3 or 4 core SWA.

Or possibly 4-core SWA to give L for power, switched L for lights (fused down as necessary), N & CPC common to both power and lights. I feel a bit uncomfortable about this though, I would rather have separate neutral cores, but if both lights and power come off the same RCBO then perhaps this is ok?

Or maybe 3-core SWA to supply both power and lights with some sort of remote wireless switching.

Any advise / suggestions?

I can easily work out voltage drop, etc, to size the cable, it's really just the number of cores I'm deliberating about at the moment.

 

[shanky887614]

I need to supply power to a couple of garden lights and a 13A socket in a longish garden.

The requirements I've been given so far are a bit vague - the socket needs to go at the end of the garden, the lights will probably go somewhere along the side of the garden, and I'm assuming that they will want to switch the lights on/off from the house. I don't know much more than that at the moment.

I plan to run SWA from the the consumer unit (a recent board with RCBO's) into the garden. The guy they've got landscaping their garden will dig the trench and bury the cable, they just want me to specify the cable at the moment.

I guess the easiest solution may be to run two separate cables, one for lights and one for power, i.e. two 3-core SWA cables. It would be nice to be able to use just one SWA cable if possible though, but I not sure how many cores I would need.

My first thought was 5-core SWA to give L+N for power, L+N for lights and a CPC common to both power and lights. But 5-core SWA doesn't seem to be that common - mostly I've seen 2, 3 or 4 core SWA.

Or possibly 4-core SWA to give L for power, switched L for lights (fused down as necessary), N & CPC common to both power and lights. I feel a bit uncomfortable about this though, I would rather have separate neutral cores, but if both lights and power come off the same RCBO then perhaps this is ok?

Or maybe 3-core SWA to supply both power and lights with some sort of remote wireless switching.

Any advise / suggestions?

I can easily work out voltage drop, etc, to size the cable, it's really just the number of cores I'm deliberating about at the moment.

you can get 5c online quite easily, i imagine some of the bigger wholesalers might stock it, if your ducting it you could use a seperate earth core if you needed for bonding (direct burial would require quite a big seperate earth considering what it will pull)

 

[Tuttle]

you can get 5c online quite easily, i imagine some of the bigger wholesalers might stock it, if your ducting it you could use a seperate earth core if you needed for bonding (direct burial would require quite a big seperate earth considering what it will pull)

No need for bonding, there's no building, he just wants a socket on a post at the end of his garden so he can plug the lawn mower in / sit in the sun with his laptop (apparently it's the only bit of his garden that gets any sun).

 

[shanky887614]

No need for bonding, there's no building, he just wants a socket on a post at the end of his garden so he can plug the lawn mower in / sit in the sun with his laptop (apparently it's the only bit of his garden that gets any sun).

you could use the armour as the cpc then outdoor fused spure to fuse down the one of the L and happy days

 

[davesparks]

4 core gives you two lives, two neutrals and a cpc.

You must not use a common neutral conductor for multiple circuits, it is forbidden by the regulations, not to mention how dangerous it would be.

 

[Tuttle]

4 core gives you two lives, two neutrals and a cpc.

You must not use a common neutral conductor for multiple circuits, it is forbidden by the regulations, not to mention how dangerous it would be.

Is it ok to use the armour as the cpc? I wasn't sure if this was frowned upon now because of corrosion problems if the cable gets damaged?

 

[davesparks]

Is it ok to use the armour as the cpc? I wasn't sure if this was frowned upon now because of corrosion problems if the cable gets damaged?

Are you an electrician?

 

[telectrix]

it's fine to use armour as cpc. if the cable is installed competently, it should not corrode before you are drawing your pension.

 

[Tuttle]

it's fine to use armour as cpc. if the cable is installed competently, it should not corrode before you are drawing your pension.

Thanks, that means 4-core is perfect then.

 

[Tuttle]

Are you an electrician?

Yes, but this is getting a bit outside my comfort zone. I would probably normally give it a miss but he's a friend.

 

[Andy78]

Thanks, that means 4-core is perfect then.

For 2 separate circuits terminating at different points and some terminating at as yet unknown positions, I would say a 4C cable would be far from perfect, and probably the last choice on my list.

 

[davesparks]

Thanks, that means 4-core is perfect then.

No it doesn't, it just means that a 4 core would comply. There is a massive difference between compliance and being sensible/best practice/good design let alone perfect

 

[Tuttle]

For 2 separate circuits terminating at different points and some terminating at as yet unknown positions, I would say a 4C cable would be far from perfect, and probably the last choice on my list.

I was looking at using a single SWA cable because it will need to be run on the surface for a bit, along the wall of the house, so I thought that one cable would look better than two cables.

 

[Andy78]

I was looking at using a single SWA cable because it will need to be run on the surface for a bit, along the wall of the house, so I thought that one cable would look better than two cables.

Aesthetics is taking a lead over suitability of wiring methods in your design ?

 

[Tuttle]

No it doesn't, it just means that a 4 core would comply. There is a massive difference between compliance and being sensible/best practice/good design let alone perfect

Ok, reading between the lines I think that you are saying that two separate cables would be more sensible / a better design, is that right?

 

[Tuttle]

Aesthetics is taking a lead over suitability of wiring methods in your design ?

Yeah, you're right. The more I think about this the more I think I am being silly. I should just have two separate cables, especially as the lights and socket are probably going to be in completely different locations.

 

[frontier219]

If they are going to be in roughly similar areas, can you not run one cable into an FCU next to the socket and run the lights from that?

 

[Andy78]

Yeah, you're right. The more I think about this the more I think I am being silly. I should just have two separate cables, especially as the lights and socket are probably going to be in completely different locations.

I think you need more info on this project as a whole, for a start you can't run cables to lights that have no position as yet, whether you are using single or multi circuit cable options.

 

[Tuttle]

If they are going to be in roughly similar areas, can you not run one cable into an FCU next to the socket and run the lights from that?

I think part of the problem is he doesn't seem to know exactly what he wants or where he wants it so it is difficult to make fully informed decisions. I don't think that the lights will be close to the socket, the garden is about 20m long.

 

[Tuttle]

I think you need more info on this project as a whole, for a start you can't run cables to lights that have no position as yet, whether you are using single or multi circuit cable options.

Yes, you're right. It sounds like the landscape gardener is itching to bury cables, maybe tomorrow, but they haven't really decided what they want yet.