Repair to a table lamp.

[FERNSEH]

Recently I was asked to repair this metal table lamp. I straight forward repair? The original metal lampholder was broken, I did not have a metal one in stock so a modern plastic replacement was chosen. Easy job you might think. A rather thin three core mains lead was originally supplied and the earth lead was connected to the lampholder. The rest of the metal parts of the lamp relied on the whole assembly being screwed up tightly together. To be honest I was not happy with this arrangement.
So I set about making this lamp safe. The three main parts, that is, the top, the cylinder and base have all been bonded together with earthing wires.
A terminal has been fitted on the base. The live and neutral leads to the lampholder have been sleeved to afford some extra insulation.
A rather elaborate repair, but I believe one can't scrimp safety with metal appliances.
Or, do you think my repair was OTT?
DFWB

[mark pirate]

Not OTT in my opinion, better safe than sorry, job well done
Mark

[Nickthedentist]

No, you've done the right thing there, David.

BTW, brass BC lampholders, complete with earth terminal, are still readily available and not expensive.

Nick.

[FERNSEH]

Originally Posted by Nickthedentist

No, you've done the right thing there, David.

BTW, brass BC lampholders, complete with earth terminal, are still readily available and not expensive.

Nick.

Hi Nick,
That white plastic lampholder doesn't look right. perhaps it might be a good idea to replace it with a metal one.

DFWB.

[G8UWM-MildMartin]

I'd say that's absolutely fine and better than new, though I'd have just run 3-core flex straight up to a new metal BC lampholder complete with earth terminal, or sheathed 2-core to the plastic one, with some kind of cord grip in either case.

[julie_m]

As long as the terminals of the lampholder are > 10 mm. from the threaded stud, the assembly would be classed as double-insulated. There's really no point not earthing the metalwork when all our power sockets are 3-pin anyway, though.

Did you test that your earth bonding wires will survive enough current to blow a 13 amp fuse? A fault causing an RCD to open when the lamp is touched is probably not as bad as the same fault starting a fire .....

[emeritus]

Last year I replaced the broken plastic lampholder of my mother's standard lamp with a brass lampholder, replacing the original 2 core flex with 3 core. My mother called the next day to say she had had a shock from it when she switched it on. I immediately went round and tested it but found no fault, but when I switched it on, I also got a shock: a discharge of static electricity, evidently picked up from the carpet.

A problem I have come across at least twice when repairing standard lamps is that the internal 1/2" brass thread of the lampholder can be somewhat oversize and the external thread of the lamp base undersize, meaning that it is impossible to screw the lampholder on tight. I have fixed this by making up a short extension from a length of 1/2" brass tube and a 1/2" brass coupler. The precision male and female threads of the tube and coupler did allow the assembly to be screwed up tightly. They are not easy to get these days, but my local branch of Ryness had some.

I have noticed that in France, brass lampholders are usually fitted with small grub screws so that you can positively lock the lampholder in the assembled position. Perhaps unscrewing is more a problem with ES lamps?

I would have it double insulated, it is safer. For example (assuming you are insulated) grab a live wire, no current, grab earthed object at the same time, current. Grab double insulated metal object, no current.

[Nickthedentist]

A tiny dab of Superglue on the male thread before screwing on the lampholder is a good way to ensure that it doesn't work loose and stress the wiring. Of course, it makes disassembly very hard though...

[Heatercathodeshort]

Originally Posted by FERNSEH

Recently I was asked to repair this metal table lamp. DFWB

Come clean David, it's YOUR lamp. Nothing to be ashamed about. I have quite a collection of 'fancy' lamps all of them pulled off tips over the years.

I have managed to palm off the most horrible ones to visiting Forum members that usually fall in love with them. They seem to go for the ones with cherubs on the shades but don't all rush because they have all been snapped up.

Just walking round my little bungalow and museum has revealed many more nasty lamps than I thought possible. All have the old wiring colours and mostly on 5amp two pin Clix plugs.

Well we all have to die some time..
Regards, John.

[Heatercathodeshort]

Oh no! I've found some more! J.

[julie_m]

Originally Posted by merlinmaxwell

I would have it double insulated, it is safer. For example (assuming you are insulated) grab a live wire, no current.

But your body is capacitively coupled to Earth; so you do get a current flow. Rubber soled shoes won't help you, either, because your whole body surface is one plate of the capacitor.

That's why children often survive blasts of mains; smaller surface area means less capacitance means higher capacitive reactance.

But your body is capacitively coupled to Earth

A darn sight less than a gavanic connexion to (say) an earthed object. If you are 1nF to ground (way over what it is) at 240V 50Hz that's less then 70uA, probably unnoticable.

[Heatercathodeshort]

This lamp, another product from the Nasty Lamp Company has a very similar shape to yours David. It dates from the late 50's but the bulb is one of those curious Philips things that dates from the 60's. It must be an early example in the use of resin for 'decorative' purposes. J.

[ThePillenwerfer]

Thanks for that, AJS. I've often wondered about that as I'd happily put my hand in a shoe and touch something live with it but know from experience that it wouldn't isolate me from earth.

- Joe

[broadgage]

Re post 14, are you certain that the bulb was made by Phillips ?
I seem to rember these odd shaped decorative lamps being made by a Scandinavian firm by the name of OY AIRAM or something similar.

Very popular in the 1960s and 1970s, and came in a variety of odd shapes, very long lasting but of low efficiency.
My late Father worked for Heals and we had a number of these lamps at home when I was a kid.

The company still exists
http://www.godcool.com/freeweb/?free...m-electric-a-b

[Heatercathodeshort]

This one is definately a Philips. The wattage is not marked. I had some others left over from the shop days but they were passed on to another Forum member. J.