Lamp wiring help

stillp · 22 May 2013

If you were to do either of those things you would not be using it in accordance with the supplier's instructions, so you would be taking responsibility for it being safe. It is clearly intended to be hung from a ceiling, i.e. out of reach under normal circumstances, and the connection terminals protected by the ceiling fitting.

The main point though is that if you were to damage the insulation by feeding that flex through a metal tube, that metal tube could become live at 240 V - perhaps not straight away but some time later. If someone wer to touch it they could receive a fatal electric shock. If the metal tube was connected to your CPC, any insulation failure between the flex and the metal tube (and thence to earth) would cause the protective device in your consumer unit to operate.

m15try · 22 May 2013

Perfect answer stillp, thanks for the lesson.

stillp · 22 May 2013

You see those 4 buttons on the right of your post? Feel free to click the furthest to the right!

m15try · 22 May 2013

stillp said:
If you were to do either of those things you would not be using it in accordance with the supplier's instructions, so you would be taking responsibility for it being safe. It is clearly intended to be hung from a ceiling, i.e. out of reach under normal circumstances, and the connection terminals protected by the ceiling fitting.

The main point though is that if you were to damage the insulation by feeding that flex through a metal tube, that metal tube could become live at 240 V - perhaps not straight away but some time later. If someone wer to touch it they could receive a fatal electric shock. If the metal tube was connected to your CPC, any insulation failure between the flex and the metal tube (and thence to earth) would cause the protective device in your consumer unit to operate.

How would I go about doing that? Use a three core flex instead of a two core i.e. introduce an earth cable? Or is it the metal tubing that will need to be connected to the CPC?

Robin0577 · 22 May 2013

The "standard" way of doing this would be....

Using a metallic lampholder with an earth terminal and connecting the CPC (earth wire) of your flex to the earth terminal. The lampholder would usually have a screw thread in the bottom and a mating screw thread would be cut on the end of the tube. The lampholder would be firmly screwed onto the tube, thus providing an earth connection to the tube as well.

In addition, the other end of the tube would normally be attached to some kind of mounting plate and usually the plate would be fitted with an earth terminal too.

m15try · 23 May 2013

Thanks Robin, cutting the thread sounds doable with a die. I've been told that I can get a lamp holder with a half inch entry thread which should screw on ok.

Correct about there being a steel wall plate. How would I go about earthing that? Is it absolutely necessary to earth that too even though it is in full contact with the rest of the lamp?

rjm2k · 23 May 2013

Correct me if I'm wrong, but an easy solution to this is to go 12v with the transformer well before the tube?

Scoby_Beasley · 23 May 2013

You've inspired me m15try!!

Wall Lamp

Scoby_Beasley
23 May 2013
1

I like that. Appeals to my steampunk side!! And has been mentioned, ignore U.S. sites on how to do stuff for the U.K.

stillp · 23 May 2013

rjm2k said:
Correct me if I'm wrong, but an easy solution to this is to go 12v with the transformer well before the tube?

Where would the transformer go?

m15try · 23 May 2013

I assume the transformer would still mean I've got the same risks, albeit a much lower voltage and less dangerous.

Also would it mean I can't use a 220V bulb as I intended?
http://www.johnlewis.com/plumen-low...0044929e9d&s_kwcid=ppc_pla&tmad=c&tmcampid=73

At the moment I'm going to go with the earthed metal lampholder plan as I've ordered new three core flex, new lampholder. However, if I have trouble attaching it I'll be at square one again and may look down the transformer route.

stillp · 23 May 2013

m15try said:
I assume the transformer would still mean I've got the same risks, albeit a much lower voltage and less dangerous.

Also would it mean I can't use a 220V bulb as I intended?

Yes, and yes. Voltages less than 50V will not usually cause a fatal shock to most adults.

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Lamp wiring help

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