Best electrical layout

[leenowell]

Hi All,

I have an existing feed to an outside area - SWA 20mm outside diameter, pro tected by 20amp trip switch. At the moment this is terminated with a single double socket. I want to add the following

2 x double sockets 4 x outside lights (2 of which will be on the same switch)

I am currently planning the wiring layout and wanted to get your views....

My plan was to take a feed from the current socket (2.5mm Hi-tuff) into a j unction box and essentially use this as the supply for the new stuff. Essen tially splitting this into 2 circuits.

The sockets are using 2.5mm Hi-tuff and the lights 1.5mm. So now the questi ons.

1. Is the 2.5mm cable to the junction box ok? The whole circuit is protecte d by 20amp fuse but in theory this could be increased in the future.

1. Should I put the 2 sockets on a little ring or just connected them radia lly from the source. Adding the existing one to the ring would be a bit tri cky as I would need to get the SWA and 2 x 2.5mm in the socket holes.

2. For the lighting circuit, I guess I have 2 options. a) take the mains supply to the switches (all 3 are together) and then conn ect it to the 3 switches taking the neutral and switched lives off to the l ights themselves b) bring the switch and light cables all back into the junction box and the n connect it all there. Anyone have a view on the best option? b) seems more flexible but getting a ll this in a junction boxes with sufficient knock outs might be challenging

4) on the supply side there is one supply but then several feeds out. Using terminal connectors would be a bit of a pain. Does anyone know of a 1 to m any connector. Almost like a sealed version of an earth block - one for liv e and one for neutral. If you see what I mean?

Thanks in advance for your help

Lee.

[Andy Burns]

It's not really splitting it, the new stuff will be a spur on the original circuit, since it's more than one single or one double socket, it needs to be a fused spur, so at the junction box you need a 13A fuse, if it was indoors you'd use a Fused Connection Unit, will the box be outside, or can you arrange for it to be indoors?

Not a lot of point, they'll be limited to 13A total, rather than 32A of a ring as norm, so treat everything on the spur downstream of the fuse as a radial.

[Mike Clarke]

Wago connectors = . My preference would be the 222 series but the new more compact 221 series could be worth considering.

Use a suitably sized empty enclosure like =

[Tim Watts]

The new ones are very nice - used some to adjust the tappings for a dashcam the other day.

[tabbypurr]

rotected by 20amp trip switch. At the moment this is terminated with a sing le double socket. I want to add the following

junction box and essentially use this as the supply for the new stuff. Ess entially splitting this into 2 circuits.

yes

increased in the future.

it can't

ially from the source. Adding the existing one to the ring would be a bit t ricky as I would need to get the SWA and 2 x 2.5mm in the socket holes.

your choice

nnect it to the 3 switches taking the neutral and switched lives off to the lights themselves

hen connect it all there.

all this in a junction boxes with sufficient knock outs might be challengi ng

both fine

ng terminal connectors would be a bit of a pain. Does anyone know of a 1 to many connector. Almost like a sealed version of an earth block - one for l ive and one for neutral. If you see what I mean?

Don't forget to 5/6A fuse/mcb the lights.

NT

[John Rumm]

Are you sure about that cable diameter - 20mm would be a petty substantial cable (i.e. 10 or 16 mm^2) for a socket!

Yup, that's fine

No need for a ring.

Whichever works best in the circumstances. I usually find it easier to make adequate space at the switch end of things to run individual switched feeds and neutrals to each lamp.

External grade box with wago terminals.

[John Rumm]

The requirement to fuse down for a spur would only apply if reducing the cable size, and the reduced size cable was not also adequately protected by the device at the origin of the circuit.

In this case the extra sockets are on an extension of the radial not a spur. So no need to fuse them.

The lighting cable is smaller, but 3 core 1.5m^2 Hi-Tuff still has a current rating of 20A, and so could also be used without additional fusing if you wanted, although personally I would include it.

[Mike Clarke]

But don't the lampholders require to be fused at 10A (or 6A for SES) ?

[leenowell]

Hi All,

Thanks very much for your replies. Some responses to your questions...

Wago connectors look perfect. I have never used them before but they look b rilliant thanks.

Double checked the outer diameter of the cable and it is definitely 20mmish (probably 21/22). The feed was always planned to go out to an outside kitc hen area so I recall it being over spec'd just in case. If the core is so big I may end up having trouble getting the 2.5mm in the fitting too!!!!

It looks like the original plan was ok except for the current debate about whether the lighting circuit requires a separate fuse or not. If it ends u p that it does require a fused is it possible to buy an outdoor fuse?

thanks again

Lee.

[leenowell]

brilliant thanks.

sh (probably 21/22). The feed was always planned to go out to an outside ki tchen area so I recall it being over spec'd just in case. If the core is s o big I may end up having trouble getting the 2.5mm in the fitting too!!!!

t whether the lighting circuit requires a separate fuse or not. If it ends up that it does require a fused is it possible to buy an outdoor fuse?

Sorry hit "post" too quickly. Thinking further about the over spec'd cable issue. If it does prove difficult to fit the 2.5mm into the same hole on t he socket I would need to replace the switch with a junction box. To save the hassle of redoing the SWA, does anyone know of a blanking plate which w ould convert the current socket back box into a junction box (if you see wh at I mean)? The current socket is one of these...

thanks

Lee.

[John Rumm]

The reduction stipulated for SES and SBS lamps was removed in the 17th edition IIRC. The other point depends a bit on the lampholder. A traditional ceiling rose complete with 0.5mm^2 drop lead may not be adequately fault protected by a Type B 20A MCB - however a bulkhead fitting might be fine.

[John Rumm]

If you look at:

That has the diameters for various SWA sizes shown. So it suggests it could be a very substantial sized cable!

You may find it easier to terminate that in a junction box first and come down to a more workable cable size.

[leenowell]

If it helps, the 3 lighting circuits are

1. 2 (or 3) outdoor post lamps with 24w energy efficient bulbs
2. a drop down to 12v to supply led strip
3. as 2 but with a controller to change the colour

[charles]

At the risk of offending a pro in this field, I'd expect a cable this size to terminate in a small CU. Then you can arrange power and lighting on separate sub-circuits.

[John Rumm]

You would not need to redo the SWA as such even if you change box. Just undo the nut[1] on the inside of the box, but leave the rest of the gland alone, and then you can re- fix it to a new box.

[1] He says casually ;-) I was attempting to connect up an extension to an existing garden socket last night and met a number of interesting challenges. The first being the normal "interesting" choice of location

- basically you site it right aove a flowed bed and next to ivy and some brambles, and the socket soon vanishes in a sea of green prickly stuff. The the socket itself had cracked and so was letting in water, not to mention whoever wired it did not use external "3 part" SWA glands - which in this case did at least let the water out - even if it did corrode the armour in the process. I also only had about 8" of SWA to work with before it went underground. So in the end chopped it back a bit, fitted a new waterproof gland and replaced the socket with a junction box, since there was no way that gland was ever unscrewing again:

Used a couple of Pihrana lock nuts to make termination of the armour easier:

[John Rumm]

Yup often that size cable would be a sub main feeding a CU or similar. In this case it sounds like its just a bit over provisioned for a single socket circuit. Nothing wrong with that as such, but it does make it harder to work with. Terminating in a small CU would be fine, if you had a building in which to locate it, and a need for a number of separately protected circuits.

[John Rumm]

When you say circuits, do you actually mean circuits (i.e. each will have its own MCB/Fuse - or just three sets of lights to be powered from the one circuit?

[tabbypurr]

Filament lamps on 20A fuse have much higher risk of exploding when they die. It's upto the OP, but I pick the lowest fuse/mcb that's effective, it simply reduces the risks.

NT

[leenowell]

Hi

Unfortunately no outside building for a CU. When I say circuit, I mean a switched light (or series of lights). Sorry poor wording.

Thanks

Lee.

[John Rumm]

No need to over complicate it then... sting up as many sockets as you want, then a FCU for the lights, and power all of them from that.