Brick wall lights - SWA cable connections

[oscar21]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

- 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]

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]

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]

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.

 

[littlespark]

of course its ok to use wagos... and possibly preferable in many instances.

I dont think i noticed anywhere, but is it 3 core cable you are using? with a core being used as an earth? (the diagram above has thrown me)

Obviously, if only 2 core, then the armour would definitely have to be earthed both ends to carry the cpc continuously from source to the last light.... If 3 core, then there is a core to be used as cpc, and the armour is simply becoming earthed protection for the cable inside. And each length of cable needs to be earthed at one end or the other.



If you are now changing the lights to surface.... do you need a Y box, or can you gland directly into the rear of the fitting?

 

[Neptune]

of course its ok to use wagos... and possibly preferable in many instances.

Thanks. I am planning to use the Steel Y Conduit and hoping there is enough space within that to link up the two SWA's and the flex that goes off to the light.

I dont think i noticed anywhere, but is it 3 core cable you are using? with a core being used as an earth? (the diagram above has thrown me)

Yes, 1.5mm 3 core cable. 1 of the core will be used as earth. In addition to the diagram above, I think I need a fly lead which goes from my Earth Wago to the steel conduit housing? Effectively, there will be three wires in the Earth Wago.

If you are now changing the lights to surface.... do you need a Y box, or can you gland directly into the rear of the fitting?

Having read all of the responses, I feel that the easiest option is to use the current housing to situate the Y Conduit with appropriate glanding. This will then provide a 2 core flex that goes through the rubber grommet at the back of the light. I will assess whether it's possible to clamp a stuffing gland on the housing of the light.

 

[westward10]

Y boxes are fine and you do not need a separate cpc to the box, threaded entries maintain excellent continuity to the armour.

 

[nicebutdim]

Having read all of the responses, I feel that the easiest option is to use the current housing to situate the Y Conduit with appropriate glanding. This will then provide a 2 core flex that goes through the rubber grommet at the back of the light. I will assess whether it's possible to clamp a stuffing gland on the housing of the light.

If there's only 5mm clearance between light and box, you won't get a Y box inside.

 

[Neptune]

If there's only 5mm clearance between light and box, you won't get a Y box inside.

5mm is based on the current lights that are designed to be recessed into the plastic housing. I am inclined to use the entire housing (approx 7cm deep) to site the Y Box and purchased new slim led lights that will be surface mounted. Hope that makes sense.