Can I supply 2 separate radials from 1 Fused Spur?

[DKMaxwell]

Hello all.

I have just bought my first house but it needs a bit of work.

I am re-wiring it and I've found the conservatory ring has been spurred off a socket in the house. I am also getting really low insulation resistance readings between L & CPC on the conservatory ring. I've located the fault between 2 sockets in the conservatory but the conservatory cables are all embedded in the brick bottom half of the conservatory. I don't want to chop out the finished brick work in the conservatory.

So I thought about changing the socket in the house to a Fused spur and have the 2 legs feeding the conservatory in the load side. Then in the conservatory, disconnect the 2 legs of the faulty cable from its sockets. This would leave me with 2 separate radials feed from 1 spur.

Is this allowed? It's not something I have ever seen before and I can not find any information on it.

 

[Lucien Nunes]

Yes, that is OK in my book. It's otherwise called a centre-fed radial, i.e. a single run of cable where the feed-in point is not at one end. In any case the original ring configuration, if indeed it is actually a spur i.e. both legs of the conservatory cable fed from a single point in the house, is incorrect (and a can of worms to analyse.) Obviously the fused spur limits the total available current in the conservatory to 13A.

 

[brianmoooore]

These will be two branches of the same radial, not two separate radials, and is absolutely fine, provided that you totally disconnect the faulty wire.

Edit: Just seen Lucien's reply, and read the OP more carefully, and it reads that you originally had a 'figure of 8' RFC arrangement, which is not permitted.

 

[DKMaxwell]

Yes, that is OK in my book. It's otherwise called a centre-fed radial, i.e. a single run of cable where the feed-in point is not at one end. In any case the original ring configuration, if indeed it is actually a spur i.e. both legs of the conservatory cable fed from a single point in the house, is incorrect (and a can of worms to analyse.) Obviously the fused spur limits the total available current in the conservatory to 13A.

Thanks Lucian. I’ll have a read up tonight on centre-fed radials.

 

[James]

I have come across a similar issue once before in a conservatory.
in this case, the faulty leg was run under the door of the conservatory that led outside.

constant flexing of the step had damaged the cable over time.

if there is a door between the 2 points you are measuring the fault between, it might be worth removing the door to check.

 

[DKMaxwell]

I have come across a similar issue once before in a conservatory.
in this case, the faulty leg was run under the door of the conservatory that led outside.

constant flexing of the step had damaged the cable over time.

if there is a door between the 2 points you are measuring the fault between, it might be worth removing the door to check.

Thanks for the reply James. Unfortunately, not in this case. The fault is between 2 sockets about 1.5m apart from each other, on the back wall of the conservatory. And the only thing inbetween them is the brick work of the conservatory. You would not be able to access the faulty cable without knocking all the brickwork of the conservatory down. The only way I can see to remove the fault is to disconnect the cable completely from each socket. But this would mean the conservatory sockets are 2 radials fed from a spur instead of a ring.
I was just wondering if anyone else had done this before or if it is against any regs?

 

[brianmoooore]

If I understand your posts correctly, it will be compliant after your modifications, but wasn't as originally installed.

 

[James]

If I understand your posts correctly, it will be compliant after your modifications, but wasn't as originally installed.

Agreed. on the assumption that it is actually a ring fed from a single point on another ring,
however, most proper sparks may well take both cables from the conservatory ring and terminate them inside a socket on an existing ring.
one cable jointed to existing socket, other to existing ring. that would then be extending the ring.

if this is the case, op must be careful to check that the ring is complete before undertaking the alterations and then again afterwards.

 

[DKMaxwell]

If I understand your posts correctly, it will be compliant after your modifications, but wasn't as originally installed.

thanks brian

 

[brianmoooore]

Take James's post #8 into consideration. He makes an important point.

 

[DKMaxwell]

These will be two branches of the same radial, not two separate radials, and is absolutely fine, provided that you totally disconnect the faulty wire.

Edit: Just seen Lucien's reply, and read the OP more carefully, and it reads that you originally had a 'figure of 8' RFC arrangement, which is not permitted.

Sorry Brian, I've only just seen this post. Yes you are correct, there was a figure of 8 RFC when I bought the property. That is one of the issues I am planning to correct whilst re-wiring.

 

[DKMaxwell]

Agreed. on the assumption that it is actually a ring fed from a single point on another ring,
however, most proper sparks may well take both cables from the conservatory ring and terminate them inside a socket on an existing ring.
one cable jointed to existing socket, other to existing ring. that would then be extending the ring.

if this is the case, op must be careful to check that the ring is complete before undertaking the alterations and then again afterwards.

Hi James. I agree that is a method of extending the ring which I have seen many times. However in this instance, the electrician who wired the conservatory actually created a figure of 8