SWA (Surprisingly Weird Arrangement)

[HandyMann]

So I’m an inexperienced novice and I accept I know two ninths of four fifths of FA but when was this arrangement ever ok?
Installing like for like replacement garden lights, currently connected to a run of 4 core 1.5mm SWA emerging from ducting under patio. Somewhere further back it’s joined to lighting circuit and then back to 6A RCBO.
Brown and blue cores utilised for L and N of lights.
Grey and Black cores are also put to use, as L and N for an outdoor 13A socket at the end of the garden. The armour is providing the cpc and zs measurements at lights show it’s doing a fine job.
The switch for the garden lights also disconnects the line to the outside socket.
Am I missing something here? I’ve told clients that the socket has to go.

 

[Spoon]

What is the socket used for?

 

[Richard Burns]

It is a foolish arrangement having a 13A socket on a 6A circuit and slightly odd that the light switch switches both socket and light cores, however it is a safe arrangement because the cables cannot be overloaded but a very inconvenient one because it would be easy to trip the circuit breaker.

 

[HandyMann]

What is the socket used for?

Lawnmower, hedge cutters, potentially anything.

 

[Deleted member 26818]

Other than the inconvenience, as long as the socket is RCD protected, it complies.

 

[westward10]

I think what he is getting at is two circuits, even though they come from the same protective device in one cable?

 

[Intoelectrics]

I think what he is getting at is two circuits, even though they come from the same protective device in one cable?

I read that the 4 core swa is jointed to an existing lighting circuit, so not sure if he meant this. Its unclear from the post the exact arrangement.

 

[HandyMann]

I read that the 4 core swa is jointed to an existing lighting circuit, so not sure if he meant this. Its unclear from the post the exact arrangement.

I inserted the rcbo as a condition of me replacing the lights dotted around the garden as it was originally MCB, no RCD protection.
1.5mm t&e normal lighting circuit at DB1 and in the light switch controlling the lights. Somewhere between the switch and the ducting under the patio this is clearly connected to the swa.
How and where I do not know however the light switch operates both line conductors in the swa. Apparently this was installed 2005/6. I’m not familiar with 16th edition and when requirements for RCD for o/s sockets came in but I thought it pre-dated this.
Also, it seems an odd arrangement to say the least that the socket only worked when the lights were switched on or vice versa.
At the jct boxes the greys of the swa are connected to each other but not identified as a line conductor
I’ve just never seen a 13A socket deliberately run (by an electrician) from a 6A MCB.

 

[littlespark]

OP states the socket is off the same switch as the garden lights.
Why wasn't the feed taken to the switch first, then looped out the supply to feed the socket? Didn't need 4 core.

Apart from that, his 6A RCBO will trip if using the lawnmower in the dark when all the lights are on.

 

[Pete999]

Sounds like a DIY disaster that has been OK until someone cops a packet. Where has this Joint between the SWA and the lighting circuit been made? that's one question I would like answered.

 

[HandyMann]

Sounds like a DIY disaster that has been OK until someone cops a packet. Where has this Joint between the SWA and the lighting circuit been made? that's one question I would like answered.

“It all got put in when we had the extension built”.
I’m not inclined to go hunting for it. I’ll just terminate the spare line and neutral at the first convenient location.
This was a spark installation not a DIY.

 

[HandyMann]

OP states the socket is off the same switch as the garden lights.
Why wasn't the feed taken to the switch first, then looped out the supply to feed the socket? Didn't need 4 core.

Apart from that, his 6A RCBO will trip if using the lawnmower in the dark when all the lights are on.

That’s pretty much why I won’t reconnect it.

 

[Intoelectrics]

I inserted the rcbo as a condition of me replacing the lights dotted around the garden as it was originally MCB, no RCD protection.
1.5mm t&e normal lighting circuit at DB1 and in the light switch controlling the lights. Somewhere between the switch and the ducting under the patio this is clearly connected to the swa.
How and where I do not know however the light switch operates both line conductors in the swa. Apparently this was installed 2005/6. I’m not familiar with 16th edition and when requirements for RCD for o/s sockets came in but I thought it pre-dated this.
Also, it seems an odd arrangement to say the least that the socket only worked when the lights were switched on or vice versa.
At the jct boxes the greys of the swa are connected to each other but not identified as a line conductor
I’ve just never seen a 13A socket deliberately run (by an electrician) from a 6A MCB.

Yes the socket would require RCD protection, so you have done the right thing by swapping out the mcb for the rcbo. As Richard Burns said the circuit/s are protected from overload so are safe from this perspective. There is nothing wrong with feeding a socket from a 6A rcbo its just not ideal as appliances rated at up to 13A maybe use and would obviously trip the breaker. I have installed a socket fed off the lighting circuit in loft areas many times to plug in lead lights or tv boosters and the like, it's just often more practical than trying to pull in a cable off the RFC if there is nothing readily available in the area. As these are unlikely to be used for anything else then the likely hood of nuisance tripping is very minimal.
In your case though it is obviously a poor design and I doubt it was an electrician that installed it in the first place. Like Pete says its most likely to be a bodge it on addition by a d.i.y'er.

 

[Pete999]

“It all got put in when we had the extension built”.
I’m not inclined to go hunting for it. I’ll just terminate the spare line and neutral at the first convenient location.
This was a spark installation not a DIY.

If that's he wasn't much of a spark imo.

 

[sham]

Wondering if you can upgrade the OCPD (mcb) to a 10A. You have to turn the lights on to use the socket. If you not going to use the socket all the time one a or twice a year. I would not care.

 

[Pete999]

Wondering if you can upgrade the OCPD (mcb) to a 10A. You have to turn the lights on to use the socket. If you not going to use the socket all the time one a or twice a year. I would not care.

I would worry more about the construction and method of jointing the two cables, to which there has been no response as yet.

 

[Spoon]

I would worry more about the construction and method of jointing the two cables, to which there has been no response as yet.

I'm still waiting for a reply from my post #2 question.....
I'm feeling rejected...

 

[HandyMann]

I would worry more about the construction and method of jointing the two cables, to which there has been no response as yet.

I’ve no idea how it’s connected to the lighting circuit and I’m not hacking out their floors and walls to find out. Zs is good and, other than the lights were old there were no reported problems. New rcbo tests well from new lights too.

 

[HandyMann]

I'm still waiting for a reply from my post #2 question.....
I'm feeling rejected...

See post #4

 

[HandyMann]

I suppose a 5A fused Connection Unit fitted to the socket feed would prevent unwanted overload tripping of the lights, should they use anything too big in the socket.