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Topic Title: Sealant recommendations
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Created On: 22 January 2019 03:25 PM
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 22 January 2019 03:25 PM
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Fitzy71

Posts: 311
Joined: 27 February 2018

I've got a job on Saturday to install some external lights over a doorway and just want to know what you guys recommend as a good sealant to use on the hole I'm drilling from internal to outside?

I'm not using any conduit externally as the cable only has to go 6-8 inches from exit hole to the light fitting.
 22 January 2019 03:33 PM
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Zoomup

Posts: 6117
Joined: 20 February 2014

I would use a silicon sealant coloured to suit the brick colour. It will stop insect invasion into the house and water ingress as well. I like to ensure that any cable entry to an eternal light is at the bottom of the light if at all possible, and that drainage holes at the bottom are clear or are drilled out as required. Is it not possible to have a rear entry to the light for the cable so that it is not seen? Perhaps drill through the wall at an angle.

Z.
 22 January 2019 03:41 PM
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AJJewsbury

Posts: 17795
Joined: 13 August 2003

Is it not possible to have a rear entry to the light for the cable so that it is not seen? Perhaps drill through the wall at an angle.

+1 for that. Unless it's a north facing wall, you'd probably have to consider UV resistance - which modern T&E isn't always too good at.
- Andy.
 22 January 2019 04:04 PM
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Fitzy71

Posts: 311
Joined: 27 February 2018

Originally posted by: AJJewsbury

Is it not possible to have a rear entry to the light for the cable so that it is not seen? Perhaps drill through the wall at an angle.


+1 for that. Unless it's a north facing wall, you'd probably have to consider UV resistance - which modern T&E isn't always too good at. - Andy.


I've got some weather resistant 3 core flex cable, where customer wants the light fitted is approx 6-8 inches above the highest point I can drill from where the cu is situated, it's a ground floor flat and cu is situated in the cupboard under the above flats staircase, hence the restriction on how high I can drill at.
 22 January 2019 04:04 PM
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mapj1

Posts: 12039
Joined: 22 July 2004

Always drill cable entries so that outside is slightly down hill from inside - eventually water or condensation will find you, and its better if it works its way out, rather than in. If it is a cavity wall, you may not be able to get a floppy wire to find its way though - either line the hole with tube, or use some sort of 'needle' of stiffer wire or rod to thread it though.
Be aware of the potential to spall off chunks of brick, and go very gently as you break through the last bit,. or make the hole undersized, and then enlarge it from both ends. Note that many TV installers carry these hole covers and jumbo hole covers for those days the drill slips

-------------------------
regards Mike
 22 January 2019 04:07 PM
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Fitzy71

Posts: 311
Joined: 27 February 2018

Originally posted by: Zoomup

I would use a silicon sealant coloured to suit the brick colour. It will stop insect invasion into the house and water ingress as well. I like to ensure that any cable entry to an eternal light is at the bottom of the light if at all possible, and that drainage holes at the bottom are clear or are drilled out as required. Is it not possible to have a rear entry to the light for the cable so that it is not seen? Perhaps drill through the wall at an angle.Z.


Good idea on matching the colour, but you can't carry loads of different colour sealant around, I was thinking of using a transparent sealant!
 22 January 2019 04:24 PM
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Zoomup

Posts: 6117
Joined: 20 February 2014

Originally posted by: Fitzy71

Originally posted by: Zoomup



I would use a silicon sealant coloured to suit the brick colour. It will stop insect invasion into the house and water ingress as well. I like to ensure that any cable entry to an eternal light is at the bottom of the light if at all possible, and that drainage holes at the bottom are clear or are drilled out as required. Is it not possible to have a rear entry to the light for the cable so that it is not seen? Perhaps drill through the wall at an angle.Z.




Good idea on matching the colour, but you can't carry loads of different colour sealant around, I was thinking of using a transparent sealant!


I mainly just carry brick brown and white sealant.

Z.
 22 January 2019 04:30 PM
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Fitzy71

Posts: 311
Joined: 27 February 2018

Ok, thanks Zoomup.
 22 January 2019 06:47 PM
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mikejumper

Posts: 2810
Joined: 14 December 2006

Clear silicone sealant for me, never used anything else around lights.
Seal around top and sides only.
For fittings such as bulkheads I also usually drill a pin sized hole through the lowest point of the fitting.
 22 January 2019 07:14 PM
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Farmboy

Posts: 171
Joined: 15 August 2018

Originally posted by: mikejumper

For fittings such as bulkheads I also usually drill a pin sized hole through the lowest point of the fitting.


Good intentions, but won't that affect the warranty and any IP rating?

F
 22 January 2019 07:18 PM
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Zoomup

Posts: 6117
Joined: 20 February 2014

Most well designed outside lights have small drain holes at the lowest points. If not I always drill a small hole to allow water drainage.

Z.
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