Ring spurred at origin?

[mattrgee]

Hi all,

DIYer here. My garage has a double socket fed by 4mm2 twin and earth connected to the same circuit breaker has the ring main for the sockets upstairs in the house. The MCB is a B32.

Is the feed in the garage considered a spur from the ring main or is it a separate radial circuit which happens to be on the same MCB? Ideally I'd like to add more sockets to the circuit in the garage (using 4mm2) but is this safe or allowed?

Thanks.

 

[Octopus]

It's a spur so no more sockets can be added ....

If you change the socket for a fused spur, then you can have as many sockets as you like, limited to 13 amps

These sockets must be protected by an rcd

 

[westward10]

It would be considered a spur and being 4.0 its method of installation would dictate whether it could carry 32A and be added to. Spurred points from ring final circuits are normally limited as to the number of points which can be served but the 4.0 clouds that a bit. It sounds like the garage socket has been a later addition and connected to the existing ring final circuit and if the existing circuit is wired using 2.5/2.5 conductors it is not ideal to have differing sizes at the same protective device, are there spare ways in your consumer unit.

 

[Pete999]

If the 4mm2 is on the same circuit breaker as the RFC then it is a Spur, as for adding more sockets to the 4mm2you would need to swap the double socket for a Fused spur unit and add sockets from that spur unit, remember the extra sockets will be limited to 13Amps governed by the fuse in the spur unit.
Another method would be to take the 4mm2 to a seperate CB (providing there is one) and form a 32 Amp Radial to your Garage (assuming it's an atatched Garage), the proviso being is that your Garage would need RCD protection, if the garage is a standalone then a different set of rules apply.

 

[westward10]

The question as to whether this 4.0 can take 32A is down to its installation method. The spur is somewhat unconventional as it stands.

 

[Octopus]

The question as to whether this 4.0 can take 32A is down to its installation method. The spur is somewhat unconventional as it stands.

it's the supply to a 2G socket so the max load is 20a

 

[mattrgee]

The question as to whether this 4.0 can take 32A is down to its installation method. The spur is somewhat unconventional as it stands.

The 4.0 is clipped along a roof joist in the garage, exposed to the air, no insulation etc. The consumer unit is actually in the garage, but there is no space for additional circuits.

We've only been in the house a few months so trying to understand what work has been done previously.

 

[westward10]

it's the supply to a 2G socket so the max load is 20a

I am considering whether it can be added to.

 

[westward10]

The 4.0 is clipped along a roof joist in the garage, exposed to the air, no insulation etc. The consumer unit is actually in the garage, but there is no space for additional circuits.

We've only been in the house a few months so trying to understand what work has been done previously.

Theoretically you could add to it but the best course is to connect to its own protective device but this is obviously not possible.

 

[Pete999]

I am considering whether it can be added to.

It could be if there is a Fused Spur Unit instead of the twin socket, the add some extra sockets, where is the problem with that?

 

[westward10]

The spur is 4.0 clipped direct so in theory if he uses the same size of cable and installation method as the existing he could add direct to it. Personally I would like to see it on its own circuit.

 

[Spoon]

Ideally I'd like to add more sockets to the circuit in the garage

What are you intending to plug into these sockets.
Is the 32A breaker protected by an RCD?

 

[mattrgee]

What are you intending to plug into these sockets.
Is the 32A breaker protected by an RCD?

Yes, protected by RCD. Sockets will be used for drill charging, Henry vacuum cleaner etc.

 

[Risteard]

I would consider it wholly unsatisfactory to have mixed sizes of cable connected in the DB like that. You're practically screaming to get poor connections.

 

[Pete999]

The spur is 4.0 clipped direct so in theory if he uses the same size of cable and installation method as the existing he could add direct to it. Personally I would like to see it on its own circuit.

A spur equates to One double or single socket
A One fused or unfused spur unit
A One fusedspur feeding a Fixed appliance.
The only way you can add more than one socket is on a 4mm2 32 or 30 Amp radial circuit if adding more than one the the cable used must be the same as the circuit is wired in 4mm2, this is the same for a 20Radial circuit wired in 2.5mm2
As the circuit in question is a Ring FC adding more than one unfused socket is not allowed

 

[telectrix]

if the CU is in the garage anyway, why not split the tails with \Henley blocks and fit a "garage board". RCD + 2/3 MCBs. then a fault in the garage will not saffect the house CU andyou would have a spare way/s. a 4mm 32A radial for sockets, 6A MCB for lights.....

 

[mattrgee]

Thanks.

Based on what's been said, is the following an acceptable way forward?

>Replace the existing twin socket with a fused spur unit, fused at 13 amps.
>Add additional sockets from the fused spur unit fed by 2.5.

 

[westward10]

This is somewhat unconventional and is clearly ad hoc, yes it should be on its own circuit as I have also suggested but the limitations of what can be added to this spur is clouded by the cable size, 4.0. Appendix 15 which is informative does not demonstrate the use of 4.0 cables/conductors.

 

[westward10]

This is somewhat unconventional and is clearly ad hoc, yes it should be on its own circuit as I have also suggested but the limitations of what can be added to this spur is clouded by the cable size, 4.0. Appendix 15 which is informative does not demonstrate the use of 4.0 cables/conductors.

 

[Octopus]

Thanks.

Based on what's been said, is the following an acceptable way forward?

>Replace the existing twin socket with a fused spur unit, fused at 13 amps.
>Add additional sockets from the fused spur unit fed by 2.5.

Yes .... And it's going to need to be tested