Do I have to earth SWA in this situation?

[Jaywn]

Hi all. I am replacing some outside lights from class 1 to class 2 due to there being no continuity on the earth and a rewire would take forever in this particular garden, plus the customer doesn't want a rewire. The exiting lights are run on t&e buried in the wall. To me it should be a matter of just swapping the lights and having them rcd protected but the customer also wants two extra lights at the other end of his garden. The only way to get a cable round to wire them up is to run SWA buried. Does the SWA armour HAVE to be earthed?

Thanks

 

[Marvo]

Yes, you must earth the armour.

 

[davesparks]

Further to that you still have to have the cpc at every point even if the fittings are class 2, you need to either disconnect the whole lot, find the fault and fix it or rewire the whole lot.

 

[bigdavs83]

Earthing the steel in the swa is to protect it from becoming a live conductor itself. It may inadvertently come into contact with the live if it becomes crushed or hit with a spade or any manner of means. It's a very slim chance but what if.....?

 

[Engineer54]

Jesus!!!! That's Amazing!!!

 

[davesparks]

Earthing the steel in the swa is to protect it from becoming a live conductor itself. It may inadvertently come into contact with the live if it becomes crushed or hit with a spade or any manner of means. It's a very slim chance but what if.....?

So it's got nothing to do with ensuring that any metal object which penetrates the cable becomes earthed before it hits a live core then?

 

[Jaywn]

Thanks guys. I completely understand that the armour is classed as an exposed conductive part and needs to be earthed but what would you do in a situation where you were terminating swa into pvc through boxes, for example a pendants , say four of them. There is no room for a banjo and there would be no continuity on the armour between each through box, so that to me seems pointless in earthing it at all. From the supply where the swa is earthed into the cu you would only get continuity to the first through box then the rest of the installation would not be earthed.

Thanks

 

[Hawk81]

Thanks guys. I completely understand that the armour is classed as an exposed conductive part and needs to be earthed but what would you do in a situation where you were terminating swa into pvc through boxes, for example a pendants , say four of them. There is no room for a banjo and there would be no continuity on the armour between each through box, so that to me seems pointless in earthing it at all. From the supply where the swa is earthed into the cu you would only get continuity to the first through box then the rest of the installation would not be earthed.

Thanks

Then the design of the job is not correct. You need to learn how to use the appropriate cable and accessories to do an install correctly and safely. Just saying there is no room to earth the armoured is no excuse for not earthing it. You need to then change the box it's being glanded into.

 

[Jaywn]

Hi. If you find that the old wiring has the cpc's cut off you would definitely need to rewire the circuit if using swa?

 

[Hawk81]

Hi. If you find that the old wiring has the cpc's cut off you would definitely need to rewire the circuit if using swa?

Surely you can answer that yourself?? How is the cable being installed? What are the chances of damage and others effects on the cable? Do you know how to design an install?

 

[davesparks]

Thanks guys. I completely understand that the armour is classed as an exposed conductive part and needs to be earthed but what would you do in a situation where you were terminating swa into pvc through boxes, for example a pendants , say four of them. There is no room for a banjo and there would be no continuity on the armour between each through box, so that to me seems pointless in earthing it at all. From the supply where the swa is earthed into the cu you would only get continuity to the first through box then the rest of the installation would not be earthed.

Thanks

Use steel through boxes!

 

[davesparks]

Hi. If you find that the old wiring has the cpc's cut off you would definitely need to rewire the circuit if using swa?

If you cannot sensibly connect the cpc of the old wiring or if the old wiring is unsuitable for any other reason then it will need to be disconnected and made safe.
It could then be replaced with a correctly designed new installation.

 

[Jaywn]

Just confused because the regs state that swa is ok if it's only earthed at the supply end. It doesn't mention continuity of the armour for the whole circuit. I could run t&e in heavy gauge pvc conduit instead of a rewire.

 

[Jaywn]

how about using heavy gauge pvc conduit instead? And making a note on the cu that anything on that circuit will need to be class 2?

 

[davesparks]

Can you quote a regulation number that states that please?
I bet you can't because there is no such regulation!
SWA may be bonded at only one end of the cable if it is just bonding which is required, if the armour is to be used as the CPC then obviously it needs to be connected at both ends.

If you run T&E in conduit you will still need to connect the cpc throughout the circuit so that it is present at each point.

 

[Jaywn]

So if you came across old imperial wiring in a house you would rewire the whole lot instead of just changing the light fittings to class 2?

 

[Marvo]

I don't see the relevance and I think you're flogging a dead horse. The regs don't allow what your trying to do.

 

[Jaywn]

The reg is 542.1.3.3

 

[davesparks]

In your original post you said you are changing light fittings to class 2 due to there being no continuity on the earth and also want to extend the circuit.
So you have a circuit which was designed and installed with an earth but it has become damaged in some way yes?

This is not the same as dealing with a circuit which has been installed with no earth because that was the correct method at the time.

If I came across old imperial wiring without a cpc on a lighting circuit and the client absoloutley refused to have it rewired or an earth installed by whatever appropriate means then I would go down the route of class 2 fittings and labelling etc, but always as a last resort.

I would never extend such a circuit to add new points to it.

 

[Jaywn]

Thanks Dave that's cleared it up for me. I will shut up now lol