Extending ring to outhouse?

[MickSmith5824]

Hi all back again needing more advice.

I've included some photos. Basically customer has asked me to supply and wire outhouse. Unfortunately as consumer unit is at front of house there's no real possibility of supplying on own circuit. The outhouse will have about 3 x double sockets and couple of lights. The thing that concerns me over the adequacy of supply is that customer would like a heater in here and also a socket for a heater in the garden....a 13 amp spur is not going to suffice in my mind. As can see from photos the only possible route can see is come from one or the two ring sockets in kitchen. To make things more awkward these sockets back onto an outside toilet ? see photo. The outhouse is about 7 metres from here. Any neat feasible point in right direction be appreciated. Have heard others suggesting a ring lollipop.....So could potentially extend ring into a large junction box opposite socket and in toilet and then could run some 6mm 3 core around the toilet, punch outside into another junction box ? then take 6mm armoured either to outhouse or preferably to garden socket first (is this feasible?) Then on to junction box in outhouse and from here wire a ring for sockets and a spur for lights. Am I missing something really stupid? Does this seem compliant to you? Or is there easier ways?

Thanks

 

[mattg4321]

Each ‘leg’ of the ring only has to be able to take 20 amps. 2.5mm2 cable is often run in insulation etc (ref method 100) meaning the current carrying capacity is only slightly over 20 amps.

If your spur to the outbuilding was towards one end of the ring, then this side of the ring could potentially become overloaded. It might even have a kettle plugged in next to the spur off to the outbuilding. This ‘side’ of the ring could then see loads well in excess of the roughly 21 amps it may be able to take.

Yes, a lot of ifs and buts, and the situation could possibly arise with a standard ring arrangement - but the set up suggested makes it more likely imo. Thus imo poor design.

That’s without getting into it being potentially a headache for the next person that comes to work on the circuit.

 

[MickSmith5824]

Each ‘leg’ of the ring only has to be able to take 20 amps. 2.5mm2 cable is often run in insulation etc (ref method 100) meaning the current carrying capacity is only slightly over 20 amps.

If your spur to the outbuilding was towards one end of the ring, then this side of the ring could potentially become overloaded. It might even have a kettle plugged in next to the spur off to the outbuilding. This ‘side’ of the ring could then see loads well in excess of the roughly 21 amps it may be able to take.

Yes, a lot of ifs and buts, and the situation could possibly arise with a standard ring arrangement - but the set up suggested makes it more likely imo. Thus imo poor design.

That’s without getting into it being potentially a headache for the next person that comes to work on the circuit.

Thanks Matt. I hear you that this maybe isn't great design, not decided fully yet on how will go about things. So to clarify then, every ring that is installed and isn't taking into account the potential loading on the legs does have a potential if heavy loads on short leg to actually overload conductors and burn out cable OCP device kicks in. Seems the logical answer is yes?

 

[mattg4321]

In reality it doesn’t happen.

That doesn’t mean I don’t like to absolutely minimise the risk of it happening though.

If I came across a set up as you are thinking of doing, then I probably wouldn’t be too worried about it, just think it an odd way of doing things.

I’d rather make the extra effort to get back to the consumer unit.

 

[MickSmith5824]

In reality it doesn’t happen.

That doesn’t mean I don’t like to absolutely minimise the risk of it happening though.

If I came across a set up as you are thinking of doing, then I probably wouldn’t be too worried about it, just think it an odd way of doing things.

I’d rather make the extra effort to get back to the consumer unit.

Ok thanks again

 

[Vortigern]

The ring final circuit in the kitchen is prone (potentially) to overload. Say they have spurred an integrated oven and have a washing machine and tumble dryer. Put the dinner in and the washing on while drying the clothes and pop outside and pop the heater on then could be overload quite easily as all of this will be on 32a RCBO or is it MCB. You will have to provide RCD protection and how will selectivity be achieved in that case? I repeat the question asked earlier, are you sure you can not use a spare way from the CU? I guess it's a terraced house and you can't run an SWA along the side of the house? Personally If there was no way I could run the circuit from the CU then I would not install it. Is it PME? Have you thought about exporting the PME?

 

[stevethesparks]

Basically a sub main from a final ring circuit is a NO.
There must be a way of running a supply back to the main CU

 

[7029 dave]

Is the supply in external meter box, if so split tails and run a sub main.

 

[MickSmith5824]

It's tns. Consumer unit is right next to front door. Ground floor property. Hard floors, stairs in way and even if could get access through stairs then in kitchen full of fixed appliances on wall would need to run circuit. To much hag for me I think I'll give it a miss. Thanks for replies all

 

[Dave OCD]

If you can get through the stairs could you run through the kitchen under the base units ?

 

[MickSmith5824]

If you can get through the stairs could you run through the kitchen under the base units ?

No to much hag think guy wants on cheap anyway will prob leave alone

 

[DPG]

No to much hag think guy wants on cheap anyway will prob leave alone

Is 'hag' another word for hassle, or has it auto-corrected both in both posts?

 

[Dave OCD]

That's been annoying me too, or is it a drastically shortened version of 'hard graft' ....

 

[MickSmith5824]

Is 'hag' another word for hassle, or has it auto-corrected both in both posts?

It is mate. Hassle is definitely what it is ?