Drilling through an external wall

[rfears]

Excuse ignorance but here goes anyway.

I want to take a cable (2.5 T&E) through an external wall. Lets assume its a normal cavity wall.

My instinct would be to drill down from inside to outside (or up from outside to inside) to minimise damp ingress -maybe 10 or 15 degrees.

I would then want to fix conduit to the outside to guide my T&E to it's ultimate destination.

Two questions:

1. is my instinct right (i.e. angle through wall) or is there a BR recommending against this?

2. whatever the orientation of the hole is there a commonly available conduit component that I can fix over the hole to take the cable into the rest of the conduit run?, and if so how do I waterproof it to minimise damp ingress into the wall? (OK, technically that's 3 questions)

Thanks

Rick.

 

[D80]

What height are you drilling at?


It would be good practice to use some conduit or the like to protect the cable here.

 

[Plonker 3]

Nothing wrong with drilling downwards as you describe. Unless it is a klisted building ior something that requires permission to dril through.

As for terminating conduit, I use a standard conduit box with a 20 mm hole in the back of it, then fill the hole with silicone sealant to waterproof it up again.

 

[rfears]

Thanks dillb, especially for the quick reply. That was exactly what I assumed. The wall in question is part of an extension to a listed building (Grade II, the building rather than the extension) - I'll go and check whether a modern extension to a listed building is also covered by the listing rules.

 

[rfears]

Thanks for the quick reply D80. Current plan is to drill through at about 1.5m above kitchen floor level - its basically fitting a fused spur for an external socket from an existing final ring, 2.5 T&E through wall, fused spur with an IP66 RCD socket set outside. The extension is modernish (1990s) so I'm guessing double brick with cavity, probably no cavity insulation (damn, it's my house, I should know these things!). Are you suggesting I need conduit through the wall? - that would make sense to me to avoid physical abrasion of the cable over time but I can't find anything in the regs to advise.

 

[Plonker 3]

If it being attached to a external wall of a listed building, I would contact LABC to find out what you can and can't do with regartds the wall as they can sometimes be very funny about things like that.

 

[rfears]

Thanks for the guide Dillb, I was sort of hoping as its a modern extension the listing boys wouldn't care too much. Why do I think that phone call is going to cost me?

 

[Doomed]

as a rule of thumb all attachments to a listed building are covered by the same listing, even modern bits.

P.S. do you ever go to bed?

 

[Guitarist]

If your RFC is already RCD protected then you won't need an RCD socket outside. Even when using an IP rated enclosure outside, I would always recommend drilling a small hole in the bottom (3mm ish) to let any water out. It's amazing how many IP rated boxes I have opened over the years to find them full of water (usually a result of accumulated condensate when wall mounted).

 

[rfears]

If your RFC is already RCD protected then you won't need an RCD socket outside.

If only... Genuine fusebox with melting wire fuses, hence the need for an RCD somewhere in the circuit.

Even when using an IP rated enclosure outside, I would always recommend drilling a small hole in the bottom (3mm ish) to let any water out. It's amazing how many IP rated boxes I have opened over the years to find them full of water (usually a result of accumulated condensate when wall mounted).

I suspect this could be a whole new thread! I can understand the logic behind the condensation theory but that suggests that there is little point in fitting a higher water resistance IP fixture in a domestic arrangement. I was thinking IP66 (Powerful water jets projected against the enclosure from any direction, such as from power jet sprays, or sea waves) since the socket will be on a patio which may at some point in the future be washed down with a pressure sprayer.

 

[rfears]

as a rule of thumb all attachments to a listed building are covered by the same listing, even modern bits.

Thanks for the tip

P.S. do you ever go to bed?

went there shortly after my post ;-)

 

[Guitarist]

I can only speak from 20 odd years of experience. An IP rated enclosure indoors or underground is one thing, but fit it to a wall where it gets very hot and very cold and whether it's IP 44 or IP68, I still drill a drain hole. Your call though, as you will be responsible for your own work. :rolleyes4:

 

[jimmymac]

Hi guys, i'm going to be putting a new post on later which is relevent to this post. Please have a read, i'd appreciate your comments

 

[rfears]

I can only speak from 20 odd years of experience. An IP rated enclosure indoors or underground is one thing, but fit it to a wall where it gets very hot and very cold and whether it's IP 44 or IP68, I still drill a drain hole. Your call though, as you will be responsible for your own work. :rolleyes4:

Bought the outside socket today, here's a quote from the instructions:

"For side, top or rear entry the LOWERMOST drain hole must be drilled out using a 5mm drill. ONLY ONE drain hole position must be drilled. For bottom entry a drain hole MUST NOT be drilled in Rear Box, but a drain hole MUST be drilled al lowermost point of conduit run. "

Capital letters as per instructions, also no mention about the upper drain hole (I assume its there for symmetry).

So there you go mate, good call!

However there is a rider:

"The drilling out of a drain hole or removing rear knock-out will reduce the IP rating of the product".

So, you buy an IPxy component, but in order to fit it you MUST (unless bottom entry) drill a drain hole which reduces the IP rating. Do I have a case for mis-selling

 

[nickblake]

If it was an MK socket they always confuse me as it says top on bottom as well as top or is it top , when i drill through walls i use off cuts of conduit and sleeve the hole 2 reasons for this one it protects the cable and to makes it so much easier to thread the cable through and three uses all the off cuts up so saves money and protects the enviroment and i only said two reasons and gave three lol its the beer from the other thread lol