Outdoor sockets

[MikeYardleyPro]

Hi all, I am getting an electrician to do couple of double sockets in my garden. There will be swa cable buried. I will run couple of 2kw heaters and some led lights from it. 
From what I have read, this needs a minimum 4mm cable. 
my electrician tells me he will extend the ring in my living room and this will allow amperage to 32amp (instead of 13 if it was a spur and that can only suppor 1 heater)

However, he will use 2.5mm cable and thats fine. He also told me the cable has 19amp rating. 
 

is this ok? Since the cable will be buried under concrete, I want to be 100% sure. 

i dont know if quotes can be discussed here but would a quote of £400 looks ok to you with 40m swa cable and 2 double sockets. 
 

thanks a lot in advance. 

 

[Murdoch]

I would recommend you get 1 or 2 more quotes, to get some perspective because 2 x 2kw heaters is more than 13 amps .......

 

[boltonsparky]

Difficult to compare the quote, how much groundworks involved etc if the spark is doing them or somebody else is, making good etc. Some outdoor sockets are a tenner others are 60 quid, a lot of variables. 

Anything outside I tend to keep separate from any existing circuits where possible, might not be doable in your case though. Even more so with their intended use/load I'd be looking at it's own dedicated circuit.

Out of interest is the kitchen part of the ring main that is intending to be extended outside?

 

[MikeYardleyPro]

It is coming out of a double socket in lounge. Groundwork is completely done by builders. I am told because it will be part of the ring, it is 32amps 

 

[Murdoch]

It is coming out of a double socket in lounge. Groundwork is completely done by builders. I am told because it will be part of the ring, it is 32amps 

sadly I have to tell you that you are being mislead.

a spur from a 32A socket circuit can only have 1 accessory on the end of it, I. E. 1 socket which can be a single or double, but not 2 separate accessories. To have multiple sockets this spur must start from a 13a fused spur

and then there is the small matter of 40 meters of cable to consider.

I strongly recommend you consult another local spark

 

[MikeYardleyPro]

Maybe I misunderstood but it wont be a spur, it will be coming out of a double socket and return to it (or a second box next to source) forming a ring 

 

[Murdoch]

Maybe I misunderstood but it wont be a spur, it will be coming out of a double socket and return to it (or a second box next to source) forming a ring 

well that make a difference but sharing an outdoor circuit with indoors always ends in tears

does said builder actually have spark involved because extending a ring by 40m isn’t a great idea either

 

[MikeYardleyPro]

No, not related, the builder will start with the garden, excavate, put concrete and slabs etc, and I thought it is best to get the sockets done taking the opportunity. 

 

[Murdoch]

No, not related, the builder will start with the garden, excavate, put concrete and slabs etc, and I thought it is best to get the sockets done taking the opportunity. 

you’ve lost me now 

 

[MikeYardleyPro]

Sorry if it was confusing. I have basically a builder doing a few jobs in the house and garden. Because the garden is getting excavated, I called a sparky I used before to give me a quote for outside sockets. Thats it

 

[MikeYardleyPro]

So the question remains, if the ring in the lounge is extended with an outside ring, will 2.5mm cable be able to run 2x2kw heaters with no issues? Once the cable is buried, thats it, no turning around

 

[SPECIAL LOCATION]

You are obviously spending a bit of money getting the garden done...

But appear to be looking for a poor solution to your electrical requirements..

Irrespective of the capabilities of an extended rings prospective max load..

Your bigger problem is more likely inconvenience in the event of a fault on the external wiring..

Other than a simple single lawnmower socket connected via a double pole isolator switch,

I would never recommend extending any circuit that is also supplying indoor accessories..

You have to ask yourself... 

When there is a fault on the outdoor wiring that trips the supply, (including any associated indoor circuits)..

How inconvenient will it be if you can't restore the power easily the same day, or next day..?

I have been to numerous faults where a badly designed installation has cause major problems because there was either..

NO independent circuit circuit for external supplies..

OR no easy switch to isolate the external wiring until the fault can be resolved..

With regard to your question about 2x 2kw heaters it is impossible to answer as you haven't given us the full circuit characteristics or loading of the existing circuit..

Take note of the words Murdoch has already said:-

sharing an outdoor circuit with indoors always ends in tears

Guinness

 

[kerching]

Seriously?

extending a ring into the garden AND with 40m SWA???

this will only end in tears

just saying

 

[revjames]

No decent sparky would do this. anything outside needs to be on its own dedicated circuit. A single run of 4mm on a radial circuit feeding the 2 sockets would do the job just fine. Or 2.5mm and rate the circuit at 20a to be on the safe side. You don't want something outdoors to interfere with power inside the house. As everyone else seems to say it will end in tears.

 

[MikeYardleyPro]

Since no one has objected to 2.5mm cable, I am

assuming it is ok. The main objection comes from the way this is done but it is not possible to have a dedicated circuit from main box, just too far and inconvenient. 
what would you do in this case? I am inclined to cancel this work.

If any issue happens with the “garden ring”, it will trip the fuse for that part right? 
 

i simply dont understand why this is any worse than me plugging 2 x 2kw heaters to an extension cable from my lounge. 

 

[revjames]

if the only way is wiring it from the lounge sockets, then I would suggest running a single cable from a 13a fused spur with a DP switch so in the event of any problems outside, you can switch off the external wiring and re set the RCBO or whatever protective device you have on the house wiring. 2x2kw heaters will however, use 16a approx so there may be an issue with prolonged use.

 

[Murdoch]

i simply dont understand why this is any worse than me plugging 2 x 2kw heaters to an extension cable from my lounge. 

and this is the problem where your understanding falls short

 If you plug 2 x 2kw heaters into an extension lead, the fuse in the plug of the extension lead will blow.

i urge you to consult other sparks 

or

 bin the idea of outdoor heaters

 

[MikeYardleyPro]

Thank you sparks! I have the same conclusion with revjames. This needs to be a spur with fused switch to isolate the garden part. I will see if I can run 2x2kw (17.2amps) on this and if it trips, then have to do with 1 heater... 

 

[Murdoch]

Thank you sparks! I have the same conclusion with revjames. This needs to be a spur with fused switch to isolate the garden part. I will see if I can run 2x2kw (17.2amps) on this and if it trips, then have to do with 1 heater... 

God this is like pulling teeth

 2 x 2 kw is about 16a and the fused spur is 13a so the 13a will blow the fuse, not immediately, but it will

Wearing a jumper is going to be easier and safer

 

[MikeYardleyPro]

Murdoch, I fully understand the maths thank you. Not every heater is exactly pulling 8.6amps because they say it on the paper. I will try and if it trips fine.