Earthing the base of a metal standard lamp

[Msitekkie]

I have been asked to rewire an antique metal standard lamp. It has been rewired previously, but not earthed..! One of the screws on the base has a short length of uninsulated wire attached, presumably from the original earthing.

Unfortunately there is insufficient space to run an extra earth wire from the lamp holder down to the base, which seems to leave me with the option of breaking into the flex at the base and using some form of junction box although it’s difficult to imagine that’s how it was done originally & any junction box would need to be pretty small. As the lamp holder is only held to the (brass) fitting at the top of the lampstand by the tension of the cable, I am reluctant to rely on the lamp holder earth.
Can anyone advise please?

 

[westward10]

A picture might help.

 

[Msitekkie]

 

[westward10]

So are you saying the brass lamp holder is not secured to the lamp as in #1. The lamp holder must be fixed to prevent undue stress on terminations and possible access to conductors. The lamp holder looks quite old does it actually have an earth terminal.

 

[DPG]

So are you saying the brass lamp holder is not secured to the lamp as in #1. The lamp holder must be fixed to prevent undue stress on terminations and possible access to conductors.

Will make changing lamps tricky as well.

 

[mainline]

Change the lamp holder for one with an earth tag on it.

 

[davesparks]

If it is relying on tension in the cable to hold it together then something is obviously wrong as this is not safe.

As above, replace the lampholder with a brass one with earth terminal and fit it properly.

 

[westward10]

I think the base of the lamp holder is fixed now I look again but the lock ring is missing from the upper part hence the cable is holding it in place.

 

[Msitekkie]

So are you saying the brass lamp holder is not secured to the lamp as in #1. The lamp holder must be fixed to prevent undue stress on terminations and possible access to conductors. The lamp holder looks quite old does it actually have an earth terminal.

The earth terminal seems to be the v shaped piece at the bottom of the lamp holder that you can see with the screw in.

 

[Msitekkie]

Will make changing lamps tricky as well.

Seems to sit on fairly firmly over the rim of the piece below, not actually fixed but I had to tug the wires a bit to get it to move when I took it off & no movement when changing lamps.

 

[DPG]

Seems to sit on fairly firmly over the rim of the piece below, not actually fixed but I had to tug the wires a bit to get it to move when I took it off & no movement when changing lamps.

The trouble is that when someone us pulling and twisting the lamp they are stressing the connections. The holder needs to be fixed

 

[westward10]

The earth terminal seems to be the v shaped piece at the bottom of the lamp holder that you can see with the screw in.

The earth terminal is normally on the base part, is the lock ring missing. The whole thing needs replacing.

 

[Msitekkie]

If it is relying on tension in the cable to hold it together then something is obviously wrong as this is not safe.

As above, replace the lampholder with a brass one with earth terminal and fit it properly.

But what is the correct method to connect to that earthing point on the base? Or are you suggesting ignoring that & relying on contact between the components (there are a couple of decorative brass rings at the neck, then steel). I am not sure a new lamp holder could be fitted any more firmly, but maybe you know different, I haven't worked on many of these.

 

[Msitekkie]

The earth terminal is normally on the base part, is the lock ring missing. The whole thing needs replacing.

Yes, this seems to be an unusual way of attaching the earth, not one of those where you poke the earth through & secure it with a screw on the outside.
Looking online I see there are some brass lamp holders that appear to have a screw on a collar at the base - is this what you mean by a "lock ring" - that this can be tightened to attach it to the post of the lamp stand?

 

[westward10]

Can you show a picture of where the earth is connected. Yes the lock ring holds it all together.

 

[Msitekkie]

Can you show a picture of where the earth is connected. Yes the lock ring holds it all together.

I presume you mean the earthing on the lamp holder in the 2nd photo. As the one on the base is pretty clear. So I have attached another photo showing the V shaped plate removed, where I believe the earth wire would go.

The discussion has got a bit side-tracked on fixing/replacing the lamp holder & it turns out this does screw on - (it was firm but not screwed on when I removed it), so apologies for not being clear on that point.

So the discussion really comes back to where we started - do I need to earth to the point on the base & if so what is the correct (original?) method. Or do we rely on earthing continuity from the lamp-holder.

 

[DPG]

I think personally I would add an extra earth wire to join the nut/bolt on the base up to the lamp holder. Is there enough room to thread one through the upright pole?

 

[Msitekkie]

I think personally I would add an extra earth wire to join the nut/bolt on the base up to the lamp holder. Is there enough room to thread one through the upright pole?

No. That's what led to my original posting & the question mark over how it was attached originally.

 

[DPG]

No. That's what led to my original posting & the question mark over how it was attached originally.

Sorry, just realised it's 3 core up the stem already. I'll re-read the thread.

 

[Msitekkie]

I think personally I would add an extra earth wire to join the nut/bolt on the base up to the lamp holder. Is there enough room to thread one through the upright pole?

Actually revisiting that issue has set me thinking about using singles, although the cable still needs to be double insulated to the plug. So I wonder if I remove some of the outer insulation where the pole narrows higher up, effectively giving me singles where needed... I have some sleeved 1.5mm earth single (flex) that I might just squeeze through if I remove the insulation from the top section of that. I think it will still be tight though.