Outside socket - waterproofing joins

[Simius]

Scenario :

(i)spur from inside the house, straight back through the cavity to outside
(ii)into outside conduit, which then carries the cable further along the wall to an outside socket

So, where the cable comes out of the wall into the conduit connection fitting, there is room for the elements to get down between the crack an onto the cable.

How do you avoid this scenario? Do you put a sealant around the fitting/wall or do you use a coupler/adaptor which sits snugly between the wall and the fitting.

I've probably not made this very clear as to which bit I mean!

 

[Spark123]

Can you post a photo?
What sort of conduit?
Is the circuit RCD protected?
Installing an outside socket it notifiable to your LABC under part p of the building regs.

 

[Simius]

Sorry, it's hypothetical. I'm currently in my 1st year C&G2330, have 17th ed and know all about notification. We were doing some conduit work the other day and got to mulling it over, like you do!

Let's say the conduit connection fitting is screwed to the wall with a hole in the back for the wire to come through. There will be a gap between the fitting and the wall, only small but enough for damp to get in and onto the cable. How do you prevent this?

Hang on, Ive drawn a picture

The red is where the damp would come in, and where you may put sealant, or not. And the blue is what a meant by putting an adaptor/female coupler in.

 

[EdwardCurrent]

Hello,

Could you not 'bush + coupler' a stub of conduit between the two boxes ?
You could 'make good' the outer hole if needed, before fitting the conduit box if you did this ?
Regards
Ed

 

[Spark123]

Metal or plastic conduit?

 

[JohnD]

I will be watching for other replies, as I don't do this sort of thing any more

old practice would be

Drill a tiny weep hole at the bottom of the box

Put a stub of conduit out of the back of the box into the house wall

accept that conduit systems are (usually) not watertight so do not expect then to be damp-free (you can Pot connections inside boxes to protect them from wet).

Since the cable sheath is waterproof it doesn't matter if that box is damp as it has no connections in it.

Sealant against the wall will come loose with movement and age.

 

[stephenf8542]

Sealant round back of box before its screwed tight to wall.galvanised or plastic conduit .Hole through wall should be at a slight angle running down so any water that may get in runs down and out

 

[Simius]

Metal or plastic conduit?

I was working with plastic when I thought about it, but either/or, if you like.

 

[Simius]

Put a stub of conduit out of the back of the box into the house wall
.

This is what I was meaning with the whole blue part in the diagram (conduit/coupler stuck through the back)

 

[Spark123]

For placcy you can drill the hole slighly bigger than 20mm, run the 20mm conduit through the wall with a female adaptor solvent cemented onto the end of it.
Be a little bit careful with the lengths as the base of the single boxes can sit recessed.
Use silicone sealant on the thread and surrounding area to seal the male bush and female adaptor to the box.
Use a lid with a gasket for the front, don't forget to solvent cement the outgoing conduit to the box also.
You can drill a hole in the bottom for a drain if you wish, or fill it with non setting compound.

 

[JohnD]

I have found that outdoor conduits and boxes usually have water in them (hence the drain and potting)

your experience may differ.

 

[Spark123]

It depends how watertight you make the whole system and where it is mounted.

 

[ban-all-sheds]

If you aren't making a joint inside the box, why have it?

Why not just bring the cable out of the wall, through a hole angled dowwards, form a drip loop, and then take the cable off to wherever it's needed?

 

[Simius]

If you aren't making a joint inside the box, why have it?

Why not just bring the cable out of the wall, through a hole angled dowwards, form a drip loop, and then take the cable off to wherever it's needed?

Doesn't the cable need mechanically protecting?

 

[sjwkmje]

Sorry, it's hypothetical. I'm currently in my 1st year C&G2330, have 17th ed and know all about notification. We were doing some conduit work the other day and got to mulling it over, like you do!

Let's say the conduit connection fitting is screwed to the wall with a hole in the back for the wire to come through. There will be a gap between the fitting and the wall, only small but enough for damp to get in and onto the cable. How do you prevent this?

Hang on, Ive drawn a picture

The red is where the damp would come in, and where you may put sealant, or not. And the blue is what a meant by putting an adaptor/female coupler in.

We would at work in this situation where the back box for the spur is in the house cut a 25mm hole in the back and screw in a male to female coupler, 25mm hole through wall with conduit fitted with resin to the coupler on the back box. Outside silicon injected around the conduit. Where it comes out you need to counter bore the brick a little to fit a second coupler to a loop out box. Resin the coupler. Everything is sealed really nice then.

We would then run clear silicon around the back of the loop box and screw from inside with two screws with silicon around the screw holes as well. Then pot the inside if there are connections, connections made with crimps etc.

Been back to a few jobs never found any signs of water ingress.

We started with plastic conduit on domestic but we have started to use galv more recently.

Adam