Found a spur on a spur (I think) in my garage

[prosist]

Hi all,

I recently bought a new house and I went to check the installation on my garage. There is a double socket and a fused switch (3A) which is connect to the light. When I opened this fused switch, I noticed it is actually a spur.

The way it is wired is that a SWA spur coming from the house is directly connected to the double socket and the same SWA goes through the fused switch to the light bulb (this is what I think sorry if I am not wording this with the proper terms).

Another thing I found is that I have all the ground floor sockets (kitchen, living room, bathroom, hallway) plus boiler plus garage all in a single 32 circuit.

My question is: Is this installation in accordance with the UK regs?

Thank you

 

[MJPD29]

Although having 1 ring circuit for the whole house isn't ideal, it's very common in older properties and unlikely ever to be overloaded anyway. As for the spur off the spur, if its just a light it's unlikely to be an jssue.

 

[littlespark]

How “new” is the house? New build or just new to you?

Agree that technically a spur from a spur shouldn’t be done.

3 storey house? Unless the top is a later loft conversion, they could have designed the installation a lot better.

 

[Julie.]

Where dies the actual cable to the garage come from, is it direct from the consumer unit (fusebox) or somewhere off the house wiring?

 

[littlespark]

Where dies the actual cable to the garage come from, is it direct from the consumer unit (fusebox) or somewhere off the house wiring?

Are you thinking, as it comes from circuit 5, it might be able to be put on a spare way as a radial?

Wider photo of the consumer unit might show it.

 

[Julie.]

Are you thinking, as it comes from circuit 5, it might be able to be put on a spare way as a radial?

Wider photo of the consumer unit might show it.

Yes, it could be a radial direct from the mcb rather than a spur, it would make more sense to terminate the swa there than off some point on the rfc.

And as swa could be suitable for protection by 32a

 

[timhoward]

If you take the view that the double socket (20A) could be two single sockets (26A) then the double and 3A spur (23A) is unlikely to be an issue in reality.
A spur off a spur is advised against but not banned outright in the regs if the current is unlikely to exceed 20A (think I remember that right, it’s a bit early)
I wouldn’t be losing sleep over this particular one, especially if it’s an LED light bulb.

 

[timhoward]

I'm also wondering if they are type AC or A RCDs with reference to the EV charge point (currently turned off)

 

[littlespark]

Just an observation, and not a steadfast rule either, but I wouldn’t have ground floor sockets and lights on the same RCD. Ground floor sockets with upstairs lights… and vice versa.

That way, if an RCD trips, you can have lights on somehow throughout the house either from ceiling lights or plug in table lamps.

 

[prosist]

Thank you for all your replies !

How “new” is the house? New build or just new to you?

Agree that technically a spur from a spur shouldn’t be done.

3 storey house? Unless the top is a later loft conversion, they could have designed the installation a lot better.

It is a brand new build, 3 storey.

Where dies the actual cable to the garage come from, is it direct from the consumer unit (fusebox) or somewhere off the house wiring?

It comes from the sockets by the TV in the living room. I have a picture of the house before the drywalls and I can see it written there "Garage Spur". So pretty sure it is not coming from the consumer unit.

Just an observation, and not a steadfast rule either, but I wouldn’t have ground floor sockets and lights on the same RCD. Ground floor sockets with upstairs lights… and vice versa.

That way, if an RCD trips, you can have lights on somehow throughout the house either from ceiling lights or plug in table lamps.

Yes, I've been told that. What is frustrating is that, being a new build, they had all the availability for doing this much better.

If you take the view that the double socket (20A) could be two single sockets (26A) then the double and 3A spur (23A) is unlikely to be an issue in reality.
A spur off a spur is advised against but not banned outright in the regs if the current is unlikely to exceed 20A (think I remember that right, it’s a bit early)
I wouldn’t be losing sleep over this particular one, especially if it’s an LED light bulb.

Thanks. Mostly I wanted to know if this is allowed in the regs, since the builders are still on site and I could ask them to change it to comply with the regs.

 

[littlespark]

Ok… so does the garage spur from behind the tv pass through a switch fuse? This would limit the load to the 13A fuse, and a “spur from a spur” wouldn’t apply.

I hope they glanded the house end of the SWA properly.

For a new new build, I would have thought a separate rfc for just kitchen sockets and possibly dedicated radial circuits for high power appliances such as washing machine.

Also a full RCBO board would be preferable, not dual RCD… (although still ok with regs) and should have an SPD fitted unless you specifically said not to.

 

[Julie.]

OK, two answers to the spur from a spur.

Firstly, the regulation 433.1.1 basically says that the cables must be protected against overload (too much current due to loading, not a fault).

If the spur is fused at the take off point, this means it's protected, so no issue, if it's just one socket outlet, again OK as there are fuses in the plugs limiting the overall current.

If however you have multiple outlets (2x13A socket + 13A fcu) this could exceed the rating of the swa (don't know size, so can't be sure) in this case it is actually prohibited, not because it's a spur from spur, but because the cable could be overloaded due to insufficient protection.

In saying that, in practical terms, swa can run hotter than pvc, so is unlikely to be an issue, especially as the fcu is only feeding a lighting circuit.

So as it is, providing it's been terminated correctly etc, it is unlikely to be a problem.

Extending it however wouldn't be possible without rework, so it does have limited adaptability in the future.

So depending upon the swa size, it could be compliant, or non-compliant but unlikely to be an issue in either case.

 

[timhoward]

So depending upon the swa size, it could be compliant, or non-compliant but unlikely to be an issue in either case.

My assumption from the photo is that it’s 1.0 or 1.5 sq mm connected to the load terminals of the FCU so ‘probably’ the SWA and T&E are 2.5 sq mm. Photo’s can be deceptive though!
Worst case tabulated CCC value would be 32A if this guess is correct.

 

[Julie.]

My assumption from the photo is that it’s 1.0 or 1.5 sq mm connected to the load terminals of the FCU so ‘probably’ the SWA and T&E are 2.5 sq mm. Photo’s can be deceptive though!
Worst case tabulated CCC value would be 32A if this guess is correct.

Yeah, that was my thought, hence if it did come direct it wouldn't be a problem either, but difficult to confirm from the photo.

 

[prosist]

OK, two answers to the spur from a spur.

Firstly, the regulation 433.1.1 basically says that the cables must be protected against overload (too much current due to loading, not a fault).

If the spur is fused at the take off point, this means it's protected, so no issue, if it's just one socket outlet, again OK as there are fuses in the plugs limiting the overall current.

If however you have multiple outlets (2x13A socket + 13A fcu) this could exceed the rating of the swa (don't know size, so can't be sure) in this case it is actually prohibited, not because it's a spur from spur, but because the cable could be overloaded due to insufficient protection.

In saying that, in practical terms, swa can run hotter than pvc, so is unlikely to be an issue, especially as the fcu is only feeding a lighting circuit.

So as it is, providing it's been terminated correctly etc, it is unlikely to be a problem.

Extending it however wouldn't be possible without rework, so it does have limited adaptability in the future.

So depending upon the swa size, it could be compliant, or non-compliant but unlikely to be an issue in either case.

Thank you very much for your clear answer.


I went through all this because I had a plan of creating a spur there (before realising it was a spur itself) to install a floodlight to the outside of the garage.
What could I do if I wanted to add a 50W light from this circuit? (please let me know if I should make a new post in DIY forum instead)