How to modernise an old brass table lamp ?

[Wilko]

Hi All, the story so far : Customer has asked me to make her old brass table lamp work. How hard could it be? No earth, so first step was some new 3 core flex and a brass lamp holder that's got an earth point. An inline switch and I'm away. But no, the new flex won't fit up the stem of the lamp, so it's out with the 5.5mm drill bit and some line boring. Got that done and screwed it all up only to find that the top half of the lamp is insulated from the bottom by a leathery insert. Not to mention the flex grommet has long since fallen out of the bottom of the fitting.

Supplier of little screw in flex grommets? ... How to earth the bottom half of the lamp? Any advice appreciated

 

[SparkyChick]

What does the brass pipe screw into?

 

[SparkyChick]

Just re-read your OP... is that black thing the leathery insert?

 

[Wilko]

What does the brass pipe screw into?

Exactly !
It screws in well but it appears it's literally a chunk leathery plasticy stuff, rather than metal. The threaded brass rod is earthed now but that doesn't transfer to the base at all. I'll break out the IR tester in a tick and see how it fares with 500V on it

 

[SparkyChick]

Sorrys, lots of posts... thinking and writing.. never good

What about a different option on the flex? You can get some really nice looking older style flex which has three cores twisted together (I'm not sure about compliance though, that's my only concern with that sort of flex). If you could use that, you could identify the earth core and split it in the base with a crimp and self tapper to earth the base, continuing up from the crimp to the bulb holder.

Another, slightly messier option might be to split the cable in the base, tap the earth and heatshrink, but that raises the issue about the heatshrink being a suitable substitute for the PVC insulation.

 

[Wilko]

Just re-read your OP... is that black thing the leathery insert?

Yes

 

[The Ghost]

Nice lamp, nice little project! Best of luck with it @Wilko

 

[SparkyChick]

Is there any room in the base for terminations? I'm thinking maybe if there is a cavity, you could terminate the cable in the base and look to fix a piece of thin plastic on the bottom (with small self tappers maybe) to provide an enclosure.

Bar enclosing the bottom and using for terminations... or squeezing an earth wire down that tube.... I was going to say, fresh out of ideas... but then I had another look at the picture.

I see the earth clamp on the light fitting includes an external portion.... does the hole down through the base of the lamp have more room than the brass tube? If so is there any way you could run it through the leathery stuff? Or maybe even put a slot in one side of the brass tube and feed an earth wire through it? If you could get a wire through that leathery stuff, it would be hidden by the fake candle until it entered the earthing terminal (small price to pay in my opinion).

Now I'm fresh out

As for the cable grip, try this place:-

Cord Grips - Lampspares.co.uk - http://www.lampspares.co.uk/cord-grips/

Looks like they have a good selection of lamp related items

Good luck and have fun.

 

[Wilko]

Thank you SC - good ideas !
There's just no way to get an extra wire up it, so I'm going to go with the "make a jb out of the base" idea. Take an earth fly lead to a sneaky self tapper in the base and then flex as per original to go to lamp holder and it's earth pin. First go at the base containment, from a 5mm nylon sheet I found lying about in the kitchen

 

[SparkyChick]

Thank you SC - good ideas !
There's just no way to get an extra wire up it, so I'm going to go with the "make a jb out of the base" idea. Take an earth fly lead to a sneaky self tapper in the base and then flex as per original to go to lamp holder and it's earth pin. First go at the base containment, from a 5mm nylon sheet I found lying about in the kitchen

View attachment 37931

Looking good

And you've got the added bonus that now things won't roll off your chopping board

 

[telectrix]

Thank you SC - good ideas !
There's just no way to get an extra wire up it, so I'm going to go with the "make a jb out of the base" idea. Take an earth fly lead to a sneaky self tapper in the base and then flex as per original to go to lamp holder and it's earth pin. First go at the base containment, from a 5mm nylon sheet I found lying about in the kitchen

View attachment 37931

where did you get those pliers. pound shop?

 

[The Ghost]

I suppose you could get a longer threaded tube to go the whole way down the lamp.
Steel 10mm Allthread 20mm Long Hollow Rod [EI2020 PLU62990] - http://www.lampspares.co.uk/steel-10mm-allthread-20mm-long-hollow-rod/?gclid=EAIaIQobChMIsLmSgLjr1QIViLvtCh25ewOMEAQYBCABEgJ3BfD_BwE
For instance

 

[westward10]

If you can fit a good restraining bush in the base the only part which would need an earth is the lampholder.

 

[Wilko]

Exactly !
It screws in well but it appears it's literally a chunk leathery plasticy stuff, rather than metal. The threaded brass rod is earthed now but that doesn't transfer to the base at all. I'll break out the IR tester in a tick and see how it fares with 500V on it

Tester maxed out at 1129V and recorded >1999 meg. Not bad for an old bit of French brassware.

 

[Wilko]

If you can fit a good restraining bush in the base the only part which would need an earth is the lampholder.

It would be very helpful if it was so, but it doesn't seem right to have the base floating ?

 

[westward10]

I know you have a class 1 lampholder but you see plenty of class 2 table or standard lamps for sale where the cable passes through metal parts. If a good insulated cord restraint is used at the base and conductors are not exposed until they are at the lampholder I see no reason to earth it. If you are worried you could use an additional layer of sleeving, how would it ever become live if the cable is securely restrained.

 

[westward10]

Tester maxed out at 1129V and recorded >1999 meg. Not bad for an old bit of French brassware.

Have you high voltage stress tested it because you shouldn't really do that.

 

[Wilko]

Oops

 

[bandit]

You could use these 10mm holed earth tag for earth integrity between ceiling rose and lamp - https://www.vintagelights.co.uk/lighting-electrical-accessories/281-earthing-tag-10mm.html

Have an awesome range of traditional fabric cable too

Run by an escaped sparky

Gareth

 

[westward10]

Doesn't need earthing