does anyone install metal or plastic trunking on exterior walls out in the elements?seen this on side of electrical wholesalers does this not defeat the object of trying to keep conduit exterior installations waterproof?ps have not looked in regulations to see how this stands.

James,
Metal trunking on the outside of buildings, is usually installed more for mechanical protection of the enclosed cabling, than weather-proofing.
Usually protection against motor vehicles, is the most common reason.

i was thinking of single insulated cables being installed in exterior trunking as you would see in conduit.

the trunking i seen was at high level, away from mechanical damage.(should of included that in first post)
the first down poor you get will fill trunking 3mm submersing cables.

James,
I'm not disparaging what it is that you have seen.
Seems rather silly to have a thing like Trunking on the outside of a building though.
Where weather-proofing is required, we would usually use PVC conduit use RTV sealant around the entry/exit points.