Garage wiring - pvc conduit & singles

[tonetone]

Hi all

I'm about to wire my garage (as part of some notifiable work which will be inspected by building control), so it's all being done properly.

I realise that the correct way to wire the garage is with conduit and 6491x wires, so that the cable is protected (ie not using surface mounted T+E that would not be acceptable) but I'm having problems confirming that plastic (round) conduit would be acceptable protection. Having gone through this forum, and the TLC tech section, I can see the derating I have to apply if I put many circuits in a conduit, and the size of conduit I require, and the 45% max loading, but nowhere can I find details of acceptable conduit construction. Is BS6099 part 2.2 the one?

If I wanted to run a larger conduit along the top of the walls, and drop a 20mm plastic down to each socket outlet (so I can fit the light cables and ring main in the same conduit) do I just use a large (eg 50*50mm) clip-on-lid trunking?

Thanks very much

Tony

 

[flameport]

I realise that the correct way to wire the garage is with conduit and 6491x wires

That is one way of doing it. Many other options, and even using T+E could be acceptable, it depends on where it is installed and if it is likely to be damaged.
e.g. - running it around the wall at floor level would probably result in it getting damaged and would not be acceptable. At a high level on the walls or roof it is unlikely to be damaged, and so could be acceptable.

Plastic conduit is fine. You could use steel, but this is just a domestic garage, and the risk of damage will be low.

As for derating - you shouldn't have any problems there, unless the circuits you install will be used at maximum capacity for long periods. Also note that a garage is likely to be much cooler than other rooms.

If I wanted to run a larger conduit along the top of the walls, and drop a 20mm plastic down to each socket outlet (so I can fit the light cables and ring main in the same conduit) do I just use a large (eg 50*50mm) clip-on-lid trunking?

Correct. This also makes future additions and modifications very easy.

 

[tonetone]

Flameport

Thanks for that - I'm worried that if I put 2 T+E in a round conduit, to drop a cable down to a socket outlet at, say, 1m high, that part of the install won't meet regs. Plus I've been reading that T+E is really hard to pull through conduit. And 2* T+E may not go through the adaptor connecting the conduit to the surface mount box. Of course the down side is that I either have to buy 6 coils of wire, or connect the lighting with T+E or 2.5mm singles...

I am glad that plastic conduit is ok, I can't imagine how much work it would be to do it in steel...

One more thing I forgot to ask, is it appropriate to use choc block in conduit boxes to wire the lighting switches? Obviously there won't be ceiling roses - I'll be using IP rated fluorescents... Only other way I can think of doing it is crimps, in the absence of a junction box.

Thanks again

Tony

 

[ban-all-sheds]

I am glad that plastic conduit is ok, I can't imagine how much work it would be to do it in steel...

It'd be interesting to learn how to do it though...

 

[333rocky333]

Instead of using conduit boxes you could use 100mm x 100 mm square plastic boxes ,if you think it will be too tight.

you could then use 25mm round the top and 20mm drops to the sockets.

Use couplers to join the pipes to the boxes.

Dont use connecters , do the three plate join within the light fitting.