Adding another spur to socket for lights?

[adiwill]

Typical diy question.
I've got a double socket near the back door. I've already added a fused spur to it to feed and outdoor socket. Can I add another to it to run an outside light?

 

[chivers67]

As long as your overall load does not exceed 13A you should be ok. What wattage is your light fitting?

 

[adiwill]

It'll be an led bulb, so very little. It has a pir but I imagine they take next to nothing.

 

[adiwill]

Also, the cable will be run inside the vent pipe box, is that okay? The switch will be on the wall of the vent box.

 

[John D v2.0]

Yes all fine, just make sure the cable is in a safe zone either vertically or horizontally from the accessory or over 50mm from the surface.
Minimum 1.5mm cable, as the whole thing is classed as a power circuit.

 

[stem]

If by:

I've already added a fused spur to it to feed and outdoor socket. Can I add another to it to run an outside light?

You mean can I connect another fused spur to the double socket by the back door, or the wiring from it to the existing fused spur. The answer is no, because you will then have two spurs from one socket.

However, if you want to add it to the outgoing (fused) side of the existing fused spur, then you can as then both will still count as one spur.

All of the above assumes that the "double socket near the back door" is wired directly on a ring circuit (or suitable radial circuit) and is not already a spur from something else.

EDIT
To clarify this post as it seems to have been misunderstood. By the above "two spurs from one socket" I am referring to adding a second spur, to the existing spur NOT. two spurs that originate from the same socket.

 

[John D v2.0]

Stem that's a common misconception and actually it turns out you're even allowed a ring with no accessories at all (eg around a ceiling void) and just spurs off for every socket.
Can save cable and reduce the loop impedence/volt drop. Agreed need to avoid a spur from a spur though.

 

[stem]

Stem that's a common misconception and actually it turns out you're even allowed a ring with no accessories at all (eg around a ceiling void) and just spurs off for every socket.

I didn't say you couldn't have a ring without any accessories and single spurs off. What I said was that you can't have a spur from a spur. If the existing socket by the back door is spurred off a ring in a single cable, it is already a spur and can't have anything else added to it. It needs to be part of the actual ring to allow this.

 

[ban-all-sheds]

What I said was that you can't have a spur from a spur.

No - you clearly said that you can't have 2 spurs from one socket:

The answer is no, because you will then have two spurs from one socket.

 

[adiwill]

Thanks all, yes the current socket is part of the ring, it's not on a spur.
So, if i understand correctly, i can run a cable from the existing spur itself, directly to the outside light (so the one spur will actually be feeding both the outside sockets, and the light). Is that correct?

 

[ban-all-sheds]

Yup, run it from the load side of the FCU, or from the outside socket.

 

[John D v2.0]

I didn't say you couldn't have a ring without any accessories and single spurs off. What I said was that you can't have a spur from a spur. If the existing socket by the back door is spurred off a ring in a single cable, it is already a spur and can't have anything else added to it. It needs to be part of the actual ring to allow this.

Just to be clear, a spur from a spur that in my previous post I agreed needed to be avoided, is where the both spurs share some cable back to the main ring. Other than that you can have 2 spurs from the same accessory or junction box on the ring if you want and that is no problem. But you should consider the balance of the ring in extreme cases.

 

[stem]

No - you clearly said that you can't have 2 spurs from one socket:

Indeed I did. You can't have 2 spurs that originate from the same socket like this.



If the post is read in context it is clarified by:

if you want to add it to the outgoing (fused) side of the existing fused spur, then you can as then both will still count as one spur.

Like this



Trust all is clear now.

 

[ban-all-sheds]

Indeed I did. You can't have 2 spurs that originate from the same socket like this.

View attachment 128036

That is not two spurs, it is one.

Trust all is clear now.

 

[stem]

It is clear, but there is a difference. In my diagram both FCU's are supplied via the same single cable originating from the socket. In your diagram each spur has its own cable directly from the ring.