Brick wall lights - SWA cable connections

Neptune · Sep 6, 2023

For various reasons out of my control, we have wound up in a situation where we have 1.5mm SWA cables buried in these pillars and exiting out of the plastic housing for the wall lights.

[ElectriciansForums.net] Brick wall lights - SWA cable connections

There are around 5 of these lights across the 5 pillars. Daisy chained with the 3 core SWA. As you can see, the wall ha snow bene plastered and finished. The house-end of this cable will be glanded into a Wiska box and punched into the house to connect to a Switched FCU.

The plastic housing set in the pillar is only deep enough to take the light!

The back of the plastic box has some screw holes for the light to fix to.

I am at a loss as to how I get these cables connected to the lights given the lack of space and hence, inability to gland these ends. If this were regular T&E it wouldn't have been an issue - from a space and connectivity point at least!

Can I please have some creative suggestions on how I get myself out of a hole. Thanks in advance.

westward10 · Sep 7, 2023

oscar21 said:
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 · Sep 7, 2023

DPG said:
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 · Sep 7, 2023

oscar21 said:
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 · Sep 7, 2023

oscar21 said:
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 · Sep 7, 2023

oscar21 said:
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 · Sep 7, 2023

nicebutdim said:
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 · Sep 7, 2023

oscar21 said:
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 · Sep 7, 2023

oscar21 said:
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 · Sep 7, 2023

oscar21 said:
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 · Sep 7, 2023

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.

oscar21 · Sep 7, 2023

davesparks said:
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.

Which is why I said if the cable is inside the wall there is no point in earthing it. Obviously the feed to them or if it feeds something else across the garden can be earthed as it wont have the same constraints with a tiny space in a wall.

Today has been really hot, after prolonged hot spells usually comes thunderstorms, tomorrow is bin day. Now its perfectly possible that I might get struck by lightning when I put the bin out, but my bin needs emptying so I'm going to risk it, I could stay inside and not take the chance but like I said, my bin needs emptying.

This is the thing with risk, you look at things objectively and make your own mind up, you don't need to do stuff just because someone else tells you to do it, no matter who they are. An unearthed SWA cable inside a wall will not hurt anyone, ever, if you are worried that it might then you might as well lock yourself in your bedroom for ever more.

oscar21 · Sep 7, 2023

nicebutdim said:
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.

I dont think not earthing a armoured cable somewhere is cowboyish, same as not putting brown sleeving on a blue switch wire, yes its against the saintly regs but cowboy, not in a million years. Also although I've not paid much attention to it so not really too sure what it covers, there is a box (or used to be) on the completion certs/EICR's that states a method of protection - PLACING OUT OF REACH- good enough for the £80 book it seems.

westward10 · Sep 7, 2023

oscar21 said:
Which is why I said if the cable is inside the wall there is no point in earthing it. Obviously the feed to them or if it feeds something else across the garden can be earthed as it wont have the same constraints with a tiny space in a wall.

Today has been really hot, after prolonged hot spells usually comes thunderstorms, tomorrow is bin day. Now its perfectly possible that I might get struck by lightning when I put the bin out, but my bin needs emptying so I'm going to risk it, I could stay inside and not take the chance but like I said, my bin needs emptying.

This is the thing with risk, you look at things objectively and make your own mind up, you don't need to do stuff just because someone else tells you to do it, no matter who they are. An unearthed SWA cable inside a wall will not hurt anyone, ever, if you are worried that it might then you might as well lock yourself in your bedroom for ever more.

As I said you are naive with regard to ADS, I also suggested you contact a cable manufacturer and ask their opinion then post it on here.

westward10 · Sep 7, 2023

oscar21 said:
I dont think not earthing a armoured cable somewhere is cowboyish, same as not putting brown sleeving on a blue switch wire, yes its against the saintly regs but cowboy, not in a million years. Also although I've not paid much attention to it so not really too sure what it covers, there is a box (or used to be) on the completion certs/EICR's that states a method of protection - PLACING OUT OF REACH- good enough for the £80 book it seems.

Placing out of reach is a legitimate means of protection albeit the circumstances are limited but I suspect this is beyond your scope of understanding.

oscar21 · Sep 7, 2023

westward10 said:
As I said you are naive with regard to ADS, I also suggested you contact a cable manufacturer and ask their opinion then post it on here.

Why would I need to contact a cable manufacturer, I know this might sound alien to you but occasionally grown up people are capable of making their own decisions without the help of other people, no matter how superior they think they are.

Can you imagine how many thousands of miles of SWA cable are installed in this country that arent properly earthed, even though they might be glanded off properly I'll bet most dont continue the earth as they should in light fittings and wiska boxes etc, it just isn't a problem in my book on a bit of inaccessible cable.

oscar21 · Sep 7, 2023

You know what I find so bizarre about technical forums like this and other sites, there are people from all walks of life participating in them, the odd one will be more saintly than god himself while others will do a bit of drink driving, some will be addicted to drugs, others go home and give their wife of kids a dig, maybe some will have even got away with murder in the past who knows. but mention that you are willing to contravene a trivial regulation and they are all over you like you are the anti-christ. Bizarre.

westward10 · Sep 7, 2023

oscar21 said:
Why would I need to contact a cable manufacturer, I know this might sound alien to you but occasionally grown up people are capable of making their own decisions without the help of other people, no matter how superior they think they are.

Can you imagine how many thousands of miles of SWA cable are installed in this country that arent properly earthed, even though they might be glanded off properly I'll bet most dont continue the earth as they should in light fittings and wiska boxes etc, it just isn't a problem in my book on a bit of inaccessible cable.

That isn't a valid educated argument.

westward10 · Sep 7, 2023

oscar21 said:
You know what I find so bizarre about technical forums like this and other sites, there are people from all walks of life participating in them, the odd one will be more saintly than god himself while others will do a bit of drink driving, some will be addicted to drugs, others go home and give their wife of kids a dig, maybe some will have even got away with murder in the past who knows. but mention that you are willing to contravene a trivial regulation and they are all over you like you are the anti-christ. Bizarre.

How is any of that relevant to the topic.

nicebutdim · Sep 7, 2023

oscar21 said:
I dont think not earthing a armoured cable somewhere is cowboyish, same as not putting brown sleeving on a blue switch wire, yes its against the saintly regs but cowboy, not in a million years. Also although I've not paid much attention to it so not really too sure what it covers, there is a box (or used to be) on the completion certs/EICR's that states a method of protection - PLACING OUT OF REACH- good enough for the £80 book it seems.

Not sleeving conductors is considered poor practice, but is nothing more than an inconvenience.

Not earthing armour is potentially dangerous. Chances are that no one will come to any harm in this instance, but then that's the case with most issues that have resulted in death - the cowboy in question finally ran out of luck.

Neptune · Sep 8, 2023

Can someone clear up a confusion of mine please:

- if this SWA was a regular T&E in copex, I assume that the earth core along with the RCD will provide protection from someone drilling into the cable or forking into it?

- The SWA also has an Earth core and will be continued through the SWA legs as I will be wago’ing them across. At this point I’m thinking, how is it different to the above scenario…

Is the additional concern the metal protective strands of the SWA? Do these also need earthing and continuity? Is this what is done through a metal gland and the earth nuts?

Thanks again

nicebutdim · Sep 8, 2023

Neptune said:
Can someone clear up a confusion of mine please:

- if this SWA was a regular T&E in copex, I assume that the earth core along with the RCD will provide protection from someone drilling into the cable or forking into it?

- The SWA also has an Earth core and will be continued through the SWA legs as I will be wago’ing them across. At this point I’m thinking, how is it different to the above scenario…

Is the additional concern the metal protective strands of the SWA? Do these also need earthing and continuity? Is this what is done through a metal gland and the earth nuts?

Thanks again

Have you not read the replies?

Yes the armour must be earthed continuously for reasons outlined above. The brass parts of the glands are used to maintain this and banjos would be bolted together (or connected through a fly lead) for this reason.

davesparks · Sep 8, 2023

Neptune said:
- if this SWA was a regular T&E in copex, I assume that the earth core along with the RCD will provide protection from someone drilling into the cable or forking into it?

No, it doesn't provide protection from someone drilling into it, nor does SWA.
With T&E the RCD would reduce the severity of any electric shock to a level which is unlikely to be fatal.
With SWA the armour ensures that any metal object penetrating the cable is connected to earth before it hits any live core thus ensuring the person remains safe and a short circuit is created to operate the circuit breaker/fuse.

Neptune · Sep 8, 2023

Came across this video from a College instructor. I suspect you have come across Gary as he publishes lots of content. If you watch it at 9:33 (and rest of the video for context) he suggests that earthing on one end is adequate.

Isn't that the point @oscar21 has made?

DPG · Sep 8, 2023

Neptune said:
Came across this video from a College instructor. I suspect you have come across Gary as he publishes lots of content. If you watch it at 9:33 (and rest of the video for context) he suggests that earthing on one end is adequate.

Isn't that the point @oscar21 has made?

Earthing at one end is acceptable yes. As long as each section of the cable is earthed, ie. the bits between each light as well.

Neptune · Sep 8, 2023

nicebutdim said:
Have you not read the replies?

Yes the armour must be earthed continuously for reasons outlined above. The brass parts of the glands are used to maintain this and banjos would be bolted together (or connected through a fly lead) for this reason.

In my situation, I will have something similar to this within each pillar:

I am planning to use the Y conduit boxes along with new surface mounted lights. Am I okay to use Wagos for the connections? Appreciate that I will need an additional fly lead from the earth Wago to the steel conduit box.

Brick wall lights - SWA cable connections

Neptune

westward10

oscar21

DPG

-

westward10

nicebutdim

oscar21

DPG

-

nicebutdim

davesparks

pirate

-

oscar21

oscar21

westward10

westward10

oscar21

oscar21

westward10

westward10

nicebutdim

Neptune

nicebutdim

davesparks

Neptune

DPG

-

Neptune

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