Ring or Radial....?

[Noob2013]

Hi all,

Im am soon to be installing 4 double sockets and possible 2 wall lights in a new conservatory.

Was going to extend downstairs ring but a tad awakward and I'm not a lover of junction boxes if they can be avoided. The consumer unit isn't too far so just as easy to install a new circuit.

I'm debating whether to go for a 2.5mm ring, 2.5mm 20 amp radial or a 4 mm 32am radial. If the wall lights are required then will be fused down via a FCU.

Obviously less Cable to run with radial and I can't imagine there will ever be much load on the few sockets.

Opinions much appreciated

 

[trev]

I'd probably install a radial, whether it be a 20 amper or a 32 is down to you and your knowledge of the install mate.

 

[NDG Elecs]

Speak to the home owner and see whether they will have elec heaters on in winter in there, and what other things they may use the sockets for.... If they plan on watching the tv whilst ironing and with a couple of fan heaters on then 2.5mm might push it. Is it a big conservatory? Just thinking re heating aspect... I suspect a 20A would prob suffice.

 

[Pete999]

Same as Trev

 

[Octopus]

Loads of conservatories run off 13a fused spurs I would look at a 20a radial

 

[Noob2013]

Cheers guys, that was my thought too

What's the general rule for wiring t&e in a brick cavity in a conservatory with only the bottom half bricked?

Obviously its more in depth for a fully bricked property with insulation, foam, likelyhood of being drilled etc.

I believe it may be brickwork then plasterboarded so would a short piece of plastic conduit between floor and socket be a better shout before its plasterboarded?

 

[Octopus]

Cheers guys, that was my thought too

What's the general rule for wiring t&e in a brick cavity in a conservatory with only the bottom half bricked?

Obviously its more in depth for a fully bricked property with insulation, foam, likelyhood of being drilled etc.

I believe it may be brickwork then plasterboarded so would a short piece of plastic conduit between floor and socket be a better shout before its plasterboarded?

You need to determine this before making any decisions!

 

[Noob2013]

You need to determine this before making any decisions!

Yeah without a doubt.

I'm having a look at the job tonight and just wanted to go there with a few ideas in my head to cover the possible options.

 

[Farmelectrics]

4mm radial all options covered then

 

[Engineer54]

Cheers guys, that was my thought too

What's the general rule for wiring t&e in a brick cavity in a conservatory with only the bottom half bricked?
?

It's generally not even half bricked, more like 5 or 6 courses!! I have no problem using the cavity on such installations, done it myself on a friends conservatory.

Don't worry about anyone telling you that the cable will be breaching the cavity gap and it'll cause damp, that's always been an old wives tale, and remains so to this day!! lol!!

 

[driverman]

It's generally not even half bricked, more like 5 or 6 courses!! I have no problem using the cavity on such installations, done it myself on a friends conservatory.

Don't worry about anyone telling you that the cable will be breaching the cavity gap and it'll cause damp, that's always been an old wives tale, and remains so to this day!! lol!!

re cables in cavity walls...........has that been banned by regs? I know it appears to be a pain re above job.

 

[Engineer54]

re cables in cavity walls...........has that been banned by regs? I know it appears to be a pain re above job.

Not to my knowledge. If it has, it wouldn't bother me too much, i'd have no problem running a cable in such a low cavity wall again.

 

[Knobhead]

4mm radial all options covered then

What?

Only a Electrical Trainee that’s afraid of the calculations for a ring would suggest that.

Being of the old school, I’d run a separate ring and a new lighting circuit.

Think about it, you have to run the 4mm[SUP]2[/SUP], so why not 2x2.5mm[SUP]2[/SUP] and a 1mm[SUP]2[/SUP] Split the two circuits either side of the board.







BTW I’ve never had to work to a budget

 

[sparksburnout]

What?

Only a Electrical Trainee that’s afraid of the calculations for a ring would suggest that.

Being of the old school, I’d run a separate ring and a new lighting circuit.

Think about it, you have to run the 4mm[SUP]2[/SUP], so why not 2x2.5mm[SUP]2[/SUP] and a 1mm[SUP]2[/SUP] Split the two circuits either side of the board.







BTW I’ve never had to work to a budget

Lucky you!! If I didn't work to a budget I wouldn't have any customers! 20A radial will murder it surely, who sits in a conservatory with 2 fan heaters going all day?

 

[Farmelectrics]

What?

Only a Electrical Trainee that’s afraid of the calculations for a ring would suggest that.

Being of the old school, I’d run a separate ring and a new lighting circuit.


dont agree with you tony theres nothing wrong in running 4mm radial you can put it on a 20a breaker if you want and im no Electrical Trainee and i can also do cable calcs the op was mentioning possible heaters getting pluged in hence why i went for 4mm cable no point running 2.5mm and the finding out hes pulling more than 20amp oh and the cable could possibly come into contact with insulation in the cavity and have its current rating capacity dramatically reduced

Think about it, you have to run the 4mm[SUP]2[/SUP], so why not 2x2.5mm[SUP]2[/SUP] and a 1mm[SUP]2[/SUP] Split the two circuits either side of the board.

 

[7029 dave]

Not to my knowledge. If it has, it wouldn't bother me too much, i'd have no problem running a cable in such a low cavity wall again.

I am with you ENG, have dropped down many with rewires, and still would apart from the cavity boys messing it all up. lol

 

[Farmelectrics]

yes thers a thought dave free cavity wall insulation has changed this got it done my self last year the house is warmer but dosent help current carrying capacitys of any cables installed in cavity walls

 

[7029 dave]

TBH Farm, how many thousands of home's have been insulated the cables are not greatly affected.

 

[Farmelectrics]

no i agree dave but the bgb has derating factors ranging from 0.51 up to 0.88 depending what length of insulation your cable is sited in

 

[Noob2013]

Thanks for all the responses.

Quick update.

- 4 double sockets and 2 ceiling lights to install.
- Sockets only required for tv + 2 lamps
- Approx total length of run = 20m
- 100mm insulation in cavity (brickwork with plasterboard)

There is one spare way in consumer unit so my plan is to put in a 20A 4mm radial supplying 4 x DSSO's and 1 x FCU (to feed the light switch + 2 ceiling lights in 1.5mm)

If the loading of sockets is increased in the future then the MCB can be increased to 32A.

Cables will run underneath the existing floorboards then clipped to the joists in the new conservatory then up through the cavity with 100mm insulation. Only approx a total of 5m of cable will be surrounded by insulation, including the lighting cable fed from FCU.

Sound ok, any suggestions?

Thanks

 

[Octopus]

On the basis that the bonding is up to date and there is RCD protection in the CU that just leaves the EIC and LABC to do!

 

[Farmelectrics]

Sounds ok to me

 

[sparksburnout]

Joists in new conservatory?????

 

[specs]

I'd probably install a radial, whether it be a 20 amper or a 32 is down to you and your knowledge of the install mate.

Ditto mate