Rewiring an old table light

[HawkEye244]

This is not earthed and I'm sure the wiring is defunct.

What work do I need to do to make it safe ?

 

[EFLImpudence]

There doesn't appear to be anything to earth.

Earthing is not a good thing in its own right.
It is a necessary evil to disconnect the supply should metal parts become live with a fault.

Just replace the cable - especially the speaker cable between plug and switch - two-core will suffice.

 

[333rocky333]

If its the metal rod you are concerned about then you could fit a Brass 10mm thread push bar lampholder, use nylon grommets each end of the metal tube and use 0.5mm 3 core flex, fit a 13amp plug with a 3 amp fuse fitted.

https://www.diynot.com/diy/threads/...or-non-earthed-plastic-which-is-safer.453789/

 

[endecotp]

Looking at your 4th picture, it seems that there is a metal tube running up the inside. I think the argument is that it doesn't need to be earthed because the cable that runs inside it is double-insulated, i.e. it is standard flex where the individual wires are insulated and then there is an outer sheath over everything.
In contrast, sometimes you get light fittings (e.g. chandaliers) where the wires inside the metal tubes are singles, often with heat-resistant insulation; in these cases, it's necessary to ensure the metal is earthed.
If you decide to replace the wire, use regular flex, not single-insulated "bell wire" or "speaker wire" like you currently have connecting to the plug, and check for any sharp edges on the metalwork while you're re-assembling it.

Personally I'm always a bit cautious about lamps like this because of a family story about someone who was killed by one. I believe that a cleaner was in the habit of always tightening it up, and in the process the wire became twisted and eventually failed; the victim was killed while turning it on. This was long before the invention of RCDs, of course.

 

[HawkEye244]

Hi chaps. I opened it up and found the tube to be plastic so do I assume I won't now need grommets either end of the tube?

Can I get away with 2 core flex on this one then, and so leaving it unearthed?

I will change the plug head with a new one and fit a 3a instead of the current 5a.

I like the brass lamp holder so will change this white one for one of those.

Is this acceptable ? : http://www.ebay.co.uk/itm/Lamp-Hold...hash=item1e8a427bf9:m:mTNra153aMMJ3HsV-hMaWLQ

 

[333rocky333]

if you fit the brass holder that will need earthing so you will need 3 core,and the earth wire terminated on the connection inside it.

If as you say the tube is plastic then you can use 2 core but it must have a plastic lampholder like you have now, if no sharp edges then no need for the grommets.

5 amp fuse is fine but some like me would fuse it at 3a and some would even use a 2a

The reason i mentioned the brass holder is because if the tube had been metal, then when the earth connection inside the brass holder is used, it in turn earths the metal tube.
Though not relevant now if as you say the tubes plastic.

 

[winston1]

View attachment 119236


I will change the plug head with a new one and fit a 3a instead of the current 5a.

Bad move, a 3 amp will likely blow on bulb failure, a 5 amp one won't.

 

[John D v2.0]

Bad move, a 3 amp will likely blow on bulb failure, a 5 amp one won't.

True for incandescent bulbs, but there's a good chance the op would be using a modern LED lamp nowadays.

 

[HawkEye244]

Here is the bulb:

 

[winston1]

Here is the bulb:

View attachment 119276

Here is the (current) bulb. Not actually a "bulb" but we won't be pedantic. Someone may replace it with an incandescent bulb though.

The fuse is to protect the cable not the "bulb" which will be internally protected. If you are not using speaker or similar wire 5 amps is OK. Using a fuse which could be lower than the internal protection is asking for trouble.

 

[securespark]

we won't be pedantic

Why the sudden turnaround?

 

[John D v2.0]

Why change the habits of a lifetime?

Well he was earlier in the sentence. Reminds me of sentences that start "I'm not being rude, but.." always end up being rude

 

[ban-all-sheds]

Someone may replace it with an incandescent bulb though.

They might.

They might decide to chew on the cable for a snack.

They might decide to bludgeon the nanny to death with the base.

What was your point, Winston? Surely it can't have been that the OP should base his actions on what some unknown unconnected stranger might do in the future, rather than what he, in full control over his own property, knows he is going to do? That would be ridiculous.

My neighbour has just bought a Toyota Landcruiser - should he not have done so because someone might use it for ram-raiding?

 

[333rocky333]

JohnW2 I recall was a frequent user of 2 amp or even 1 amp fuses, I do not recall him ever reporting one blowing,
In the past I have fitted many Table lamps on 5 amp fused plugtops and BS646 fuses have been around since 1958,
Mk 601, 602,603 to fit them.

 

[winston1]

In the past I have fitted many Table lamps on 5 amp fused plugtops

Plugtops (covers) don't have fuses. Plugs do.