Enclosing twin and earth in conduit.

[ImayKnow]

I have a mains cable that runs from the house into the garage.

In the garage it is just pinned to the wall with cable clips but I wish to now enclose it in 20mm diameter plastic conduit. Two questions I have are:

1) how far apart should I put the spacer bar saddles, and where should they be positioned? (I will have a few 90 degree elbows, a three way tee and a couple of 1 way terminal boxes (which I was planning to drill at the back where the cable comes through into the garage, and goes back into the house at the end of the run)). The total length of the run will be about 8 metres.

2) how do I drill the existing plastic surface boxes (one by 1G and one by 2G) to accept the male adapters into which the conduit will enter them??

Thanks

 

[plugwash]

2) how do I drill the existing plastic surface boxes (one by 1G and one by 2G) to accept the male adapters into which the conduit will enter them??

If you absoloutely have to drill holes in hard plastic "patress" boxes then it can be done by going very carefully with a holesaw but they crack easilly.

Probablly better to buy new boxes designed for use with conduit.

 

[ImayKnow]

2) how do I drill the existing plastic surface boxes (one by 1G and one by 2G) to accept the male adapters into which the conduit will enter them??

If you absoloutely have to drill holes in hard plastic "patress" boxes then it can be done by going very carefully with a holesaw but they crack easilly.

Probablly better to buy new boxes designed for use with conduit.

Thanks plugwash. I did get a couple of them from screwfix, but they only have one entry point (Tower brand), ideally I could do with an entry hole at the bottom and top as the cable runs vertically into the 2G socket.

 

[ban-all-sheds]

I have a mains cable that runs from the house into the garage.

What size cable, and what MCB rating?

1) how far apart should I put the spacer bar saddles,

Every m or so - but check the makers recommendations, as not all conduits are equal. Does it get very hot in there in the summer?

and where should they be positioned?

Evenly...

(I will have a few 90 degree elbows, a three way tee and a couple of 1 way terminal boxes (which I was planning to drill at the back where the cable comes through into the garage, and goes back into the house at the end of the run)). The total length of the run will be about 8 metres.

Good luck pulling twin & earth through that

2) how do I drill the existing plastic surface boxes (one by 1G and one by 2G) to accept the male adapters into which the conduit will enter them??

I wouldn't bother trying - replace them with boxes with knockouts designed for use with conduit.

 

[ban-all-sheds]

Thanks plugwash. I did get a couple of them from screwfix, but they only have one entry point (Tower brand), ideally I could do with an entry hole at the bottom and top as the cable runs vertically into the 2G socket.

http://www.tlc-direct.co.uk/Main_In...ries_Metal_Clad_Index/Metal_Clad_1/index.html

 

[DetlefSchmitz]

(I will have a few 90 degree elbows, a three way tee and a couple of 1 way terminal boxes (which I was planning to drill at the back where the cable comes through into the garage, and goes back into the house at the end of the run)). The total length of the run will be about 8 metres.

Make sure you use inspection elbows, so you can pull the cable through.

 

[DetlefSchmitz]

sorry - double post

 

[plugwash]

Even if they don't have knockouts in the right places PVC boxes are a lot less likely to break when drilling than the brittle "patress" boxes.

I would also note that one should use singles where possible when working in conduit. T&E is likely to be a massive pain to pull in.

You also have to choose between inspection elbows/tees and circular conduit boxes. The former look neater but give much less space to work.

 

[ImayKnow]

Cheers folks. I wondered about getting metal clad sockets and boxes, but found a spare plastic pattress and chain drilled / filed it to allow the male adapters to fit. Tbh it did break slightly at the back where it is thin to allow the box to be broken for cable entry. I have just siliconed around this, more to prevent anything small falling in, but no way could you get even a small finger into it.

I may still consider the metal ones, but thanks for all the advice. All the elbows are the inspection type, but I am hoping that if I assemble as I route the cable (rather than assemble and try to run cable through the full length) then all will be well - but you experts will know what is ahead of me, I will find out tomorrow!

Thanks again

 

[RF Lighting]

A very light film of fairy liquid on the cables will make pulling them into the conduit 100 times easier

 

[securespark]

Or the wholesalers sell KY jelly for cables!

 

[ban-all-sheds]

A very light film of fairy liquid on the cables will make pulling them into the conduit 100 times easier

That sort of thing always makes me laugh - I used to know someone who referred to her, um, you-know, as her fairy.

 

[ImayKnow]

Job done!

Firstly I fixed as much conduit in place as possible, then stripped it down and reassembled it piece by piece whilst also threading the twin and earth through the smaller sections of conduit as the reassembly took place.

It took a while but all is nice and neat and secured.

I can imagine it would be virtually impossible trying to feed 2.5mm cable through 20mm conduit with several elbows in situ!

Thanks again to you electricians for your time and guidance - it was much appreciated.