Another exterior wiring question

[Ian]

As I mentioned on another thread, I'm planning on wiring up some exterior lights and an exterior socket. I'm wondering what to do about the short lengths of cable that will be exposed in both cases.

Just to summarise what I'm planning:

- I intend to drill through the wall of an outhouse to feed the socket.

- I am planning two PIR-controlled lights. Again one will be on the wall of the outhouse, so I will just be drilling directly through the wall. The other is a few metres away on the side of the main house and I am planning to run the cable in heavy duty PVC conduit (the outhouse is attached to the house).

Based on advice I received on this group a few months ago (I'm pretty slow at getting around to these things!), my understanding was that it was OK to run standard T&E cable in the conduit as the conduit would protect it from weather and knocks.

However, now that I have received the stuff I ordered I see a potential problem - it seems like it is going to be difficult to avoid having at least a few cm of cable exposed between the conduit and the PIR entry holes. I can't see a way of getting a good seal between the conduit and PIR. The lights themselves are less of a problem as I can see a way to join the conduit to the light housing.

There is a similar problem with the fittings mounted on the outhouse walls: even though I can drill through more or less directly where the fitting is mounted, again there will be a few cm between the hole in the wall and the entry hole in the fitting. (I haven't bought a socket yet but the ones I've looked at in Wickes have their cable knockout holes around the sides of the fitting, but none in the back.)

So, in summary:

- Should I be worried about these exposed lengths of cable?

- Is there some way I can weatherproof/protect them?

- should I not be using standard cable after all, but something weatherproof instead? (This would be a pain as I've already bought the cable etc. for the job.)

[rrh]

Actually you may (according to the electricians' On-Site Guide) use ordinary T&E "on exterior surface walls, boundary walls and the like" without further protection although "protection from direct sunlight may be necessary. Black sheath colour is better for cables in sunlight". Also "additional protection may be necessary where exposed to mechanical stress" (common sense really).

I have some ordinary T&E - grey or white sheath, I forget - feeding a PIR light on a south-east facing outside wall for the past 15 years or so and it's still in perfect nick; there is about a metre from the hole in the wall to the light fitting.

[Andy Hall]

It isn't a good idea to have exposed PVC cables really.

How about using a weatherproof enclosure and mounting the PIR on the lid with the wiring going through the base

one example, but TLC have a range of different ones if you need a different size.

These have knockouts to take 20mm conduit adaptors.

The general alternative id HiTuf.

.andy

To email, substitute .nospam with .gl

[Lurch]

On 30 May 2004 11:47:36 -0700, ian [e-mail] (Ian) strung together this:

No, not at all. PVC is not a problem on external walls, despite what the books say, it is however recommended to be protected.

You could run the conduit tight up to the entry point, if that's not possible then as someone else said an adaptable box can be used.

No, PVC is fine.

[Christian McArdle]

Correct.

Nothing a 20mm hole saw can't fix!

Well a couple of cm probably won't hurt, although the best technique is to use Hi-Tuf cable, which is UV resistant and can be run in sunlight with impunity. However, given that you already have the PVC, I'm sure you can contrive something to protect those few cm from UV and give you that warm fuzzy feeling from doing it right.

Christian.

[Ian]

Thanks to all who replied.

The consensus seems to be that ideally I should protect against UV. For the very short lengths of exposed cable we are talking about, mechanical stresses are not an issue, so I wondered about this as a potential solution:

amalgamating tape).

Although it isn't described on the tlc site itself, a google around the web suggests this stuff is suitable for waterproofing and UV protection. Anyone have any experience of this or opinions on its applicability here?

Thanks,

Ian

[Huge]

I've used it for years to protect the coax feeding amateur radio aerials and their connectors. It needs protecting against sunshine itself, so what I do is to lap the SAT over the connectors (stretch it 50% to make it amalgamate), then cover the SAT with insulating tape, then paint over with bitumen paint/mastic.

The last lot of aerial connectors I took down were as dry, bright and clean as the day I put them up, after 11 years.