Table lamp earthing

[jhs14]

Hi all,

I have a large copper vase that I intend to turn into a table lamp. The vase has a narrow neck so my plan is to glue or fix a brass lampholder to the neck of the bottle using lamp bungs that are available for this purpose.

I will then drill a hole through the back of the vase and feed the cable through, fitting a cord grip to the hole. I will cut a hole in the base of the vase big enough to reach inside to make the necessary connections.

My question is, do I need to be concerned about earthing of the vase? My method of fixing the lampholder to the vase will probably involve fixing it to the inside of a short length of conduit glued inside the neck of the vase, and therefore the lampholder won't be in direct contact with the vase.

Nonetheless I feel like I should be earthing the vase to make sure - is that right?

If so, the only way I can think of doing it is to drill another hole through the back of the vase and fit a bolt through the vase body, taking an extra earth flex from the lampholder to fix to the inside of the bolt. Is this the best way?

Thanks,

 

[Taylortwocities]

The brass lampholder will have an earth terminal, you must earth that.
Your brass base is what is defined as an "exposed conductive part" and this must also be connected to earth.

 

[stem]

Generally proprietary metal electrical fittings come in two categories.

Class 1 fittings are earthed as you describe

Class 2 fittings are "double insulated" and do not require an earth.

Personally, I would connect an earth. However, if you were able to run a length of flexible conduit from the base of the lamp holder that passes right through the metal base, and then thread the cable through that, so that there is no chance of the cable touching any part of the metal, and the conduit is fixed securely in position so that it does not move, then effectively it is double insulated.

If you do run the cable through the base of the lamp even if it is earthed, you should still fit a grommet to the hole where it exits to prevent the cable chafing.

Also, the brass lampholder will still require the earth connection. [unless it's double insulated ]

 

[Taylortwocities]

Stem
Producing an item that complies with the requirements for Class II (double insulated) is not something that a DIYer should even think about attempting.

Just earth the lampholder and the base.

Meerkat

• Taylortwocities
• 11 Dec 2009
• 53

Simples!

 

[jhs14]

The brass lampholder will have an earth terminal, you must earth that.

Of course - I will connect the earth flex to this terminal, my question is is it necessary to run an additional earth from this terminal to the base.

 

[stem]

Producing an item that complies with the requirements for Class II (double insulated) is not something that a DIYer should even think about attempting.

It would still be better than some proprietary fittings. This one for example

 

[jhs14]

Personally, I would connect an earth. However, if you were able to run a length of flexible conduit from the base of the lamp holder that passes right through the metal base, and then thread the cable through that, so that there is no chance of the cable touching any part of the metal, and the conduit is fixed securely in position so that it does not move, then effectively it is double insulated.

Well that was my thinking. The neck of the bottle is a good deal wider than the 20mm conduit, which I will fit in place with gripfill or something similar (will be hidden by the lampshade so not too concerned by looks) - there's likely to be at least 5mm of clear air (or gripfill!) between the brass lampholder and the vase body.

Equally, the flex will be continuous between the plug and the lampholder, protected by a plastic cord grip (screw-through type) where it enters the vase body.

So I'm pretty confident it is effectively 'double insulated', even if it is DIYed. Little voice in the back of my head says I should put a earth bolt through the back of the vase though, so I might as well.

Is there a better way to do this other than a chunky set screw and nut? Can you buy screw-through earthing lugs, for example?

Thanks for the replies,

 

[Taylortwocities]

So I'm pretty confident it is effectively 'double insulated', even if it is DIYed. Little voice in the back of my head says I should put a earth bolt through the back of the vase though, so I might as well.

Is there a better way to do this other than a chunky set screw and nut? Can you buy screw-through earthing lugs, for example?

Anything can happen over the lifetime of something like this. It can fall over, flex can get yanked, all sorts.

For your own piece of mind (and to save another three pages of comments) earth the base and the lamp holder. You cannot rely on a bit of plastic & Gripfill to be your lifeline.

You can get all sorts of earthing lugs, I would use crimp ones,
http://www.screwfix.com/p/insulated-crimp-blue-ring-5mm-pack-of-100/24964

if you have a proper rachet crimping tool..

Or just secure the bare earth wire with a nut, bolt and shakeproof washers. A small one will do just fine.

.

 

[333rocky333]

Nut and bolt is hideous.

If you cant ensure continuity between lampholder and the base then
Normal practise is solder an earth tag inside the base, however you then may have problems securing the flex and an earth wire into the lampholder entry point

http://www.cordsncables.co.uk/acata..._tag__earthing_terminals_for_table_lamps.html