Garden electrics - extending existing outdoor socket

[dhutch]

How do you know that the current outdoor socket, on its own circuit, is on a ring not a radial?


Daniel

 

[samm1978]

How do you know that the current outdoor socket, on its own circuit, is on a ring not a radial?


Daniel

H Daniel

I saw them install it back in 2010

 

[samm1978]

Any advicev would be greatly appreciated

 

[Aragorn84]

what size is the circuit breaker?

I guess potentially, you could break the ring and treat it as two radials? Feed one to the shed, and another servicing the socket and two FCU's?

Assuming its a 20A MCB and 2.5mm cable that would probably be fine?

In the shed i wouldnt bother with a CU, Fit a DP isolator, and an FCU for the lighting. You can use the FCU as the light switch.

 

[samm1978]

what size is the circuit breaker?

I guess potentially, you could break the ring and treat it as two radials? Feed one to the shed, and another servicing the socket and two FCU's?

Assuming its a 20A MCB and 2.5mm cable that would probably be fine?

In the shed i wouldnt bother with a CU, Fit a DP isolator, and an FCU for the lighting. You can use the FCU as the light switch.

Can I ask what the benefit of having two radials is over extending the existing ring as in the diagram below?

Untitled

• samm1978
• 27 Mar 2014
• 1

The ring is on a 16A MCB and 2.5mm cable. Is the suggestion to connect two branches of a radial circuit to one MCB?

I'd want the DP isolator on the house wall so I can turn off all electrics in the shed without having to cross the garden. I'm assuming at the shed I'd just split the feed using a junction box - one line to the socket and the other to the FCU/light?

Thanks for all your help by the way. I'm much clearer on what I need to buy and have in place for my electrician.

 

[Aragorn84]

Basically because it shouldnt be a ring.

No idea why they've installed it as such, especially with a 16A MCB its just a waste of cable. To continue trying to make it a ring, your just wasting more cable, and making things needlessly complicated.

One single piece of 2.5mm cable can carry 20-25A, and ring arrangement was designed to allow the raising of that to 32A without haivng to use thicker cable, by looping it back to the supply and forming parallel paths. In many properties, the extra amount of cable needed to turn the socket circuit into a ring is quite short, so it saves copper and gives more current capacity.

But to run a ring for what you describe makes no sense. Given its on a 16A breaker, its completely pointless trying to keep it a ring.

I would split it, use one leg of the ring as a radial to feed the garage, and the other leg as a radial to feed the sockets and FCU's. And yes, you can happily connect both radials to the same MCB.

This means in future you can if desired seperate the two out into different MCB's, if you'd like more power or more control over the circuits.

I would also concur with your point about a DP isolator at the house end of the cable to the shed, however i'd put one in the shed as well, to give a local single point of isolation for the shed electrics.

 

[samm1978]

Basically because it shouldnt be a ring.

No idea why they've installed it as such, especially with a 16A MCB its just a waste of cable. To continue trying to make it a ring, your just wasting more cable, and making things needlessly complicated.

One single piece of 2.5mm cable can carry 20-25A, and ring arrangement was designed to allow the raising of that to 32A without haivng to use thicker cable, by looping it back to the supply and forming parallel paths. In many properties, the extra amount of cable needed to turn the socket circuit into a ring is quite short, so it saves copper and gives more current capacity.

But to run a ring for what you describe makes no sense. Given its on a 16A breaker, its completely pointless trying to keep it a ring.

I would split it, use one leg of the ring as a radial to feed the garage, and the other leg as a radial to feed the sockets and FCU's. And yes, you can happily connect both radials to the same MCB.

This means in future you can if desired seperate the two out into different MCB's, if you'd like more power or more control over the circuits.

I would also concur with your point about a DP isolator at the house end of the cable to the shed, however i'd put one in the shed as well, to give a local single point of isolation for the shed electrics.

Aaah it all makes sense now. Thanks a lot for your help Aragorn. Its much appreciated.