20mm Plastic Trunking

[ban-all-sheds]

And using nothing is even cheaper.

In a way I can understand the OP's problem - I hate seeing cables clipped to walls, but I'm not sure that conduit (be it electrical or water) looks a lot better, particularly if it isn't, or doesn't remain, a dead-straight run.

If I had to have conduit outside, I'd use metal, but that would only be after I had exhausted every other possibility of running the cables inside so that they didn't need concealing.

 

[ericmark]

I had a catenary cable fail, and the question is just 2 years old, yet what it replaced was twin and earth over 30 years old, protecting cable from sunlight may be a good idea however not sure it has any practical use? The big problem with cable outside is it needs to be round to go into a gland, however pond cable is round, it is black so reasonably good at resisting UV rays, so using that only reason for conduit is to hold the cable from becoming a festoon, drooping between every clip.

The German method of free air between each length of conduit will in the main remove the expansion and contraction problem, but since only for looks and clearly needs to be black to resist UV once the sun has started to make its surface turn white I don't think it looks any better than the cable on its own.

Where there are a number of cables then yes it makes them look tidy. But for single cable why bother?

 

[JohnW2]

... it is black so reasonably good at resisting UV rays ... and clearly needs to be black to resist UV once the sun has started to make its surface turn white ...

That certainly seems to be the case, but I've often wondered about this.

Maybe I'm wrong, but I would have thought that a black object would be an extremely good absorber of UV, just as it is of visible light (after all, that's why it looks black!). Whilst I can see that a black sheath would prevent most of the UV getting to (and potentially damaging) the cores of the cable, as far as the sheath itself is concerned, I would imagine that it's the UV-susceptibility of the material which matters, not it's colour - after all, there is an awful lot of white plastic being used in sun-exposed locations which claims to be fairly UV-resistant.

Kind Regards, John

 

[sparkwright]

There should always be drainage points at the lowest points of the conduit so I'm not sure what your point is.

Even if conduit is watertight the fact remains that condensation will occur within it, and without drainage holes it will not be able to escape.

Are we saying that there is no need to glue the conduit joins?

And that if the conduit contracts with the weather, it's not a problem if a coupler comes apart, and lets rain in, because there are drainage points?

I think preventative measures should be taken.

Often, a pvc conduit box will come with a gasket with it's lid, so there must be some desire to keep conduit systems watertight.

 

[JohnW2]

Are we saying that there is no need to glue the conduit joins? And that if the conduit contracts with the weather, it's not a problem if a coupler comes apart, and lets rain in, because there are drainage points?

I think it's being said (at least by me) that there is no problem with water getting into a conduit system (since, from the water pount of view, the cable(s) would be perfectly happy left 'exposed to the elements'), per se, provided that measures have been taken to prevent it getting into, and accumulating in, accessories, fittings, JBs etc.

As has been said, one should not have a completely sealed system, since, even if there is no water ingress, there is a risk of condensation within the conduit, accessories etc. - so one has to have provision for drainage.

Often, a pvc conduit box will come with a gasket with it's lid, so there must be some desire to keep conduit systems watertight.

As above, even when there is a watertight lid, one still will normally have to (be advised to) have drainage holes.

Kind Regards, John

 

[sparkwright]

My point is, though, no water should be allowed in anywhere near the top, and the drainage holes should be at the bottom.

I don't think unnecessary water should be allowed to enter, only exit.

Ega weld is readily available, do people not bother gluing pvc conduit systems when the use them outside?

 

[333rocky333]

Agreed, on all counts.

Kind Regards, John

surely it contravenes Reg 521-04-01 (iv)

 

[JohnW2]

surely it contravenes Reg 521-04-01 (iv)

Could you translate that into 17th ed-speak?

Kind Regards, John

 

[JohnW2]

My point is, though, no water should be allowed in anywhere near the top, and the drainage holes should be at the bottom. ... I don't think unnecessary water should be allowed to enter, only exit.

That's obvioulsy true of anything containing live conductors/parts (e.g. accessories), but it isn't really true of conduit, per se.

Ega weld is readily available, do people not bother gluing pvc conduit systems when the use them outside?

As has been said, if the runs are of significant length, if the glue the joints of outdoor plastic conduit which will be subjected to considerable thermal cycling, it will become a mess very quickly. This is not a case of being "too lazy to glue" but, rather, "deliberately not gluing"

Kind Regards, John

 

[sparkwright]

I can't see much difference between an accessory and it's associated conduit, TBH, if it's all connected.

I assume we are talking about conduit with bush end joiners to, for example, outdoor sockets and the like, wired in singles.

Would not gluing the joins make a tidier and/or safer job once the thermal cycling takes place? I thought the glue may keep it together a bit longer at least.

 

[JohnW2]

I can't see much difference between an accessory and it's associated conduit, TBH, if it's all connected.

There's a big difference if things are arranged so that the conduit only enters accessories etc from below

I assume we are talking about conduit with bush end joiners to, for example, outdoor sockets and the like, wired in singles.

Not at all, and that's the whole point. We are talking about using conduit to protect from UV, and to (in some people's minds!) improve the aesthetics of an (insulated and sheathed, multi-core) cable which could otherwise be left fully exposed, clipped to the building.

Would not gluing the joins make a tidier and/or safer job once the thermal cycling takes place? I thought the glue may keep it together a bit longer at least.

If long lengths of plastic pipe are rigidly joined together, the pipe will buckle and bend, maybe even crack, when it expands/contracts - one needs 'sliding' joints of some sort.

Kind Regards, John

 

[sparkwright]

I'm talking about where the conduit and the accessory are joined directly via bush ends and the like.

In an earlier post I pointed out some conduit will only enter the accessory at the bottom, so the conduit could safely allow water only into the conduit, and then escape through drainage points.

My point is when using conduit which doesn't enter the bottom of an accessory.

Sorry if I hadn't made myself clear of this.

 

[JohnW2]

My point is when using conduit which doesn't enter the bottom of an accessory. Sorry if I hadn't made myself clear of this.

Fair enough, but that makes life much more difficult, particularly if the only possible entry is at the top.

Kind Regards, John

 

[sparkwright]

Exactly, which is one of several reasons why I avoid using it outside.

Obviously it is important to design it well if there is no option other than pvc conduit.

But you do see many badly designed conduit systems which will take in water, and even if there are drainage points I don't like the idea of water potentially running over live terminals.

 

[securespark]

I have never had an issue with plastic conduit outside but I usually only use it for bonding conductors.
I always use black conduit and solvent weld for all the joints and provide support with saddles at regular intervals, usually 3 per metre outside. I also drill drainage holes.