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Posted By Topic: Antique metal chandeliers

SafeSparky
May 07 2018 16:50

I have a rewire job where most of the light fittings are metal and non earthed. I can rewire some to include an earth, and rewire others to be double insulated, and some a mixture of both (earth the metal base where there are single insulated terminals, double insulate down the chain to the lamp holders). There are some fittings that are impossible to do either with due to having no tidy way to terminate an earth or not having enough room for one (or even double insulated flex).

My plan is to install isolating transformers on these fittings instead.

To my interpretation of best trade practises and rules, all these solutions would be acceptable, but I'd just like to hear what other people do in these situations where earthing/double insulating/replacing fittings are not an option.

I would appreciate any feedback that some more experienced guys out there might have ie Sarmajor, AlecK and Pluto to name a few. You guys always seem to have a good working knowledge around these tricky ones.

Thanks in advance!
   

mf51to1
May 07 2018 20:15

Are the lamp holders brass?
   

SafeSparky
May 08 2018 07:20

Some are brass and some are plastic. There is one that is made of skinny brass tube that has brass lamp holders, but the tube is so skinny and full of single insulated wires already that I can't fit an earth in. Would be good if they made a .3mm double insulated appliance wire.
   

AlecK
May 08 2018 08:58

Are they out of "arm's reach"?

More precisely, do they still comply with original rules that applied when they were installed? If so, ESR 113 allows them to remain is service and ESR 59(3) allows you to maintain them in "original condition".

As an example, if installed under 1976 Regs, they wouldn't have needed an earth if the room has a non-conducting floor and they are at a height that they cannot readily be touched and are out of reach of any earthed metal.
   

SafeSparky
May 08 2018 10:09

They are not out of arms reach unfortunately, most hang down to 2.3m or less. They are all wired in trurip or speaker wire. Can something that looks like speaker wire stay in service under the old rules? Or has that never been ok? That floors are wooden but can't guarantee there won't be a Class 1 appliance nearby when lamps are being changed etc.

Is there any practical way to earth a brass lampholder that has no earth terminal?
   

AlecK
May 08 2018 11:45

There wasn't a definite minimum height, just "cannot readily be touched". 2.3 m is arguably too low (I can just reach it, but I'm not especially tall). And you're right to consider what other (earthed) equipment might be placed nearby - it might be that they climb onto that in order to reach the lamps - and you can guarantee that they won't isolate first (switching off at the usual wall switch is not isolation).

The wiring within the fitting is not our problem; it's part of the equipment not part of the installation.

Leaving aside "compliance", adding an RCD to the relevant circuit(s) will improve safety.
   

Satobsat
May 08 2018 20:25

"Is there any practical way to earth a brass lampholder that has no earth terminal?"

Yes there is. Brass BC lamp holders with both metric and imperial threads are still available, my local supplier has them on the shelf at a reasonable price to. These brass fittings have the earth terminal you require. You can also get brass bases for them so that they can be screwed onto standard lamp posts etc. I'm not 100% sure but I also think you can get brass tubing from the same company, (you will need to thread them yourself) should you need a larger internal diameter for more wires.

Depends how much your client likes the fittings and is willing to invest in them.

I wired a new house for a client that had spent considerable time and money sourcing period art deco light fittings, they were very nice fittings but 90% of them required upgrading.
   

SafeSparky
May 08 2018 21:43

Thanks for the responses guys.

I started stripping the fittings today to try figure out what I can do with them. Good news is I can effectively earth 4 out of 5 of them and there is enough room to rewire where I need to. I have found that a 6mm M10 lug with a toothlock washer (for added conductivity) works quite well if you put it over the 3/8 inch threaded tube at the base of some of the fittings and tighten it down with a nut. I sourced some nuts from a local fasteners supplier ($1.50 each even after discount).

There is one fitting that has no provision for that so I am going to try soldering a PEC onto the inside of the base - it's flat and no way to add a nut without seeing it from the finished side. I'm not sure how well soldering a wire onto a flat surface will work (with regards to mechanical strength and potential discolouring of the finished side) but I'll give it a go. As long as i use heaps of wire and solder I guess it should be fine. I will cable tie it to the live wires so it can't be yanked when fitting is taken down too. The only issue then is conductivity to the rest of the fitting. The whole thing is brass and is on some kind of swivelling ball joint at the base. When I tested conductivity through the base to the rest of the fitting it was a little bit inconsistent, but I think when its hanging it should be tight enough to provide a satisfactory test result. As I'm replacing the main board I'll be adding RCD protection too so I guess all in all it should stop any potential unsafe situation arising.

I'm still interested to hear people's thoughts on the apparent speaker wire and whether or not that can be considered acceptable. As long as it passes a IR test I see no problem with it, how am I to know what spec that wire was manufacturered to? It very well could be 230V rated and used for it's copper colour that's visible through the clear insulation (it blends into the rest of the fitting where it runs down chain etc).

I would also like to hear what people think about using an isolating transformer if all else fails. Obviously this will negate any advantage of RCD protection so maybe not a good idea at all.

Has any else needed to use isolating transformers in modern electrical work?


   

OwenK
May 08 2018 23:35

Isolating transformer would work fine. I’ve had to do it once where the manufacturer of heated ceiling panels thought that if he cut a 1000W element in half he could get two 500W panels. But when the power goes on and you can see the scorch mark in the painted ceiling showing exactly where the element is ...
We installed 230/110V isolating transformers with fused output on the affected circuits and everything was fine. Nice variation for the manufacturers to pay
   

AlecK
May 09 2018 08:55

Yes there's still a place for separated supplies.

When I'm standing in the harbour drilling holes in wharf piles, I'll take a tranny over an RCD every time; an RCD only limits the duration of the shock whereas a separated supply eliminates the shock (for a single earth fault).

For you application yes separated supply is an acceptable option for fault protection under clause 2.4.1; but you still need to have an equipotential bonding system in place so all exposed conductive parts (fittings / parts of fittings) are connected together. If you can't get that, then one item / appliance per transformer.

And you still need both overload & short circuit protection, which needs a bit of care for the short circuit aspect 'cos the tranny won't pass the high current we usually rely on to operate overcurrent devices.
   

SaintAlan
May 09 2018 11:01

The 'speaker wire' you describe was some horrible single-insulated stuff used during the Trurip days. It hardens and cracks when warm like a lamp. Maybe it complied at the time but I rip it out anywhere I find it.
I have repaired several old light fittings and found modern 0.75mm 2c+e flex could be wiggled through the brass tube, then the E terminated at the lamp-holder with a small brass bolt.
   

AlecK
May 09 2018 12:14

and where 0.75 mm2 won't go, 0.5mm2 often will
   

SafeSparky
May 13 2018 15:31

AlecK - what is the best way to ensure the tx is provided with satisfactory overcurrent and short circuit protection? Would it have built in overload and short circuit protection? Would an in line appliance fuse be sufficient for SC if the tx has a built in overload? I have priced up a 150VA isolating tx but hadn't requested it to be compliant with any particular standard. I guess I should contact the manufacturer and ask them to confirm these details.

I have another job now to install two metal pendant lights in a two storey house with 2 core lighting. I am thinking of using a tx for this too. My plan is to install a flush panel door below the light switch to house the 2 transformers (1 per light) Maybe one of those entertainment boxes for behind tvs would be suitable.
   

AlecK
May 14 2018 07:42

You'll find the appropriate Standard for isolating transformers listed in Schedule 4 of ESRs
   

pluto
May 14 2018 17:34

My reading of the earhing requirements for luminaires AS/NZS 3000 clauses 5.4.4 and 5.4.3 shows that the use of an isolating transformer does NOT remove the need to provide an earthing conductor at the luminaire position.

The conession of NO earthing conductor at the luminaire position is only applicable if the luminiaire is operating off ELV (up to 50 V AC).
   

AlecK
May 15 2018 09:45

If Pluto had bothered to read the OP, he might have noticed that we're NOT talking about installing new lighting points, ONLY about improving the safety of existing points that do not have a PEC because they (likely) weren't required to have one when they were installed.

   

Andrew
May 15 2018 09:57

In any case, 5.4.3 only requires an earth to the transformer, and 5.4.4 has an exception for where it's not required in 5.4.1 - which has an exception for protection by electrical separation per 7.4