Brick wall lights - SWA cable connections

[Neptune]

What is on the other side of the wall.

The footpath and street

 

[westward10]

Doesn't matter what you do 12 months down the line half of them probably won't even be functional.

 

[Neptune]

Is there a reason why some space could't be made above or below the light? This question has been asked more than once, but I don't see any meaningful response.

10 min per light with an SDS and cables could be made off properly, then a bit of Tuff sheath or HO7 brought through the rear in a single stuffing gland.

It would be as easy to do this right as mess about with less than ideal 'solutions'.

I wanted to avoid having to make it good afterwards.

Also, the cable is buried in the construction of the wall. If we SDS’d above or below, it will need some digging before the cables can be released.

 

[Neptune]

Doesn't matter what you do 12 months down the line half of them probably won't even be functional.

How come?

 

[westward10]

How come?

Fact of life, put a light fitting into an external wall or floor and nature will see to it failing.

 

[nicebutdim]

I wanted to avoid having to make it good afterwards.

Also, the cable is buried in the construction of the wall. If we SDS’d above or below, it will need some digging before the cables can be released.

The box provides 5mm of space, so the choice is quite simple - dig them out or mount lights over these on the surface. None of the suggested solutions (good or bad) are going to work within 5mm confines.

 

[westward10]

I was working at a large school last week and three of the external stairways had brick lights, probably twelve in total and none functioned. Probably installed three years or so ago and for one the mcb bangs straight off.

 

[oscar21]

SWA isn't just flex with steel armour and an outer sheath, as has been suggested. The stuff that covers the basic insulated cores is not to be considered a sheath, and in many cables it's just what is referred to as bedding. This bedding is often fragile and crumbles as you try to remove it. As such, it would not be ideal to try and use a stuffing gland around it to provide water ingress protection.
And the armour must be earthed, as already strenuously noted.

Which is why I said the outer sheath goes into the stuffing gland, it clamps down onto the pvc outer, its just that the SWA bit isn't glanded to anything. You are aslo saying the SWA must be earthed, maybe you can tell me why it must, other than the regs saying it should. What possible scenario may happen if its not earthed, we are talking about a cable sandwiched in a brick wall here, not under a flower bed etc. Like I've said, I've done exactly the same thing with copex and flex which complies with every reg so why earth the SWA?

 

[DPG]

Which is why I said the outer sheath goes into the stuffing gland, it clamps down onto the pvc outer, its just that the SWA bit isn't glanded to anything. You are aslo saying the SWA must be earthed, maybe you can tell me why it must, other than the regs saying it should. What possible scenario may happen if its not earthed, we are talking about a cable sandwiched in a brick wall here, not under a flower bed etc. Like I've said, I've done exactly the same thing with copex and flex which complies with every reg so why earth the SWA?

If there is damage to the cable resulting in contact between a core and the steel armour then nothing will happen. The steel armour will be live and nothing will trip.

I think you must know this though.

 

[nicebutdim]

Which is why I said the outer sheath goes into the stuffing gland, it clamps down onto the pvc outer, its just that the SWA bit isn't glanded to anything. You are aslo saying the SWA must be earthed, maybe you can tell me why it must, other than the regs saying it should. What possible scenario may happen if its not earthed, we are talking about a cable sandwiched in a brick wall here, not under a flower bed etc. Like I've said, I've done exactly the same thing with copex and flex which complies with every reg so why earth the SWA?

Perhaps you mis-typed.

Here's your comment:

Not quite if you cut the armoured bit back quite far you are left with the inner bit which is just like flex, although the sheath is a bit on the thin side, I was suggesting fit two stuffing glands into the light somewhere and clamp these onto where you cut the armoured strands so they are just inside the gland. Even if it was wired in flex I wouldn't trust that grommet to keep the water out, especially with two cables in it.

 

[westward10]

Which is why I said the outer sheath goes into the stuffing gland, it clamps down onto the pvc outer, its just that the SWA bit isn't glanded to anything. You are aslo saying the SWA must be earthed, maybe you can tell me why it must, other than the regs saying it should. What possible scenario may happen if its not earthed, we are talking about a cable sandwiched in a brick wall here, not under a flower bed etc. Like I've said, I've done exactly the same thing with copex and flex which complies with every reg so why earth the SWA?

Forget Regulations, consult a cable manufacturer and ask their opinion then post it on here.

 

[oscar21]

If there is damage to the cable resulting in contact between a core and the steel armour then nothing will happen. The steel armour will be live and nothing will trip.

I think you must know this though.

That could be said for loads of things though, ceiling grids, metal stud work, pipes that cross cables, double insulated fittings, socket screws in dry lining boxes, just a few of the top of my head. Chances of it happening though....zip. And even if it did the rcd would save you.

 

[DPG]

That could be said for loads of things though, ceiling grids, metal stud work, pipes that cross cables, double insulated fittings, socket screws in dry lining boxes, just a few of the top of my head. Chances of it happening though....zip. And even if it did the rcd would save you.

The SWA is part of the electrical installation though.

Plus an armoured cable outside is more susceptible to damage and degradation.

Double insulated fittings fundamentally should not have an earth.

You can't rely on an RCD as a means of covering for using bad workmanship.

 

[westward10]

That could be said for loads of things though, ceiling grids, metal stud work, pipes that cross cables, double insulated fittings, socket screws in dry lining boxes, just a few of the top of my head. Chances of it happening though....zip. And even if it did the rcd would save you.

To suggest an RCD would save you is naive and shows a lack of understanding of ADS.

 

[nicebutdim]

That could be said for loads of things though, ceiling grids, metal stud work, pipes that cross cables, double insulated fittings, socket screws in dry lining boxes, just a few of the top of my head. Chances of it happening though....zip. And even if it did the rcd would save you.

What would an RCD detect if a live conductor was in contact with armour that isn't earthed?

 

[oscar21]

What would an RCD detect if a live conductor was in contact with armour that isn't earthed?

Well you when you touch it, and if you don't touch it, so what if its live, which it wont be, only in a bookworms fantasy world

 

[DPG]

Well you when you touch it, and if you don't touch it, so what if its live, which it wont be, only in a bookworms fantasy world

So you're happy that a fault leaves part of the electrical system live with no protective devices tripping? Your mitigating circumstances are that an RCD will hopefully trip if someone touches it.

To be honest if someone has left armour unearthed then they probably haven't bothered testing the RCD.

 

[nicebutdim]

Well you when you touch it, and if you don't touch it, so what if its live, which it wont be, only in a bookworms fantasy world

And depending on the circumstances that could be a fairly bad shock - assuming the RCD works.

Earlier you took issue with the idea of being called a cowboy, even though no one had done so, and now it seems you've decided to play that part.

 

[davesparks]

Which is why I said the outer sheath goes into the stuffing gland, it clamps down onto the pvc outer, its just that the SWA bit isn't glanded to anything. You are aslo saying the SWA must be earthed, maybe you can tell me why it must, other than the regs saying it should. What possible scenario may happen if its not earthed, we are talking about a cable sandwiched in a brick wall here, not under a flower bed etc. Like I've said, I've done exactly the same thing with copex and flex which complies with every reg so why earth the SWA?

We have no idea where the cable runs, the outgoing one may go underground, may be buried in the wall in a safe zone or may be run along some random route.

Kopex and flex doesn't necessarily comply with every regulation.

The armour should be earthed for many reasons. One not often mentioned is that earthing it prevents a capacitivley coupled voltage (aka phantom voltage, ghost voltage and often incorrectly called an induced voltage) occurring on it, this is the same reason unused cores in a cable should always be earthed or safely terminated.

 

[pirate]

Inexpensive fittings will fail in such conditions, maybe next year, maybe the following year. My solution would be to buy good quality fittings designed for the marine environment, and surface mount them, leaving the existing back-box available for proper termination.
I'm talking proper marine lights here, not some crappy stuff that's got a shell of poor quality stainless steel for show. I've had light fittings on boats for years that have never failed even though they are constantly exposed to the salt water spray and salty air.
Sadly, it seems that unfortunately not enough thought went into this project, so maybe best to go to Plan B.