Removing sensor from touch lamp

[Alison556]

I've got a touch lamp that isn't touching any more and it's too nice a lamp to chuck out, so I've put an inline switch in.

It's flickering and going in and out though so I'm guessing the sensor/controller is causing a problem so I was going to take that out.

The lamp has a metal base though and there's a disc of plastic screwed inside the base - with it being a metal base, would it need an earth? It's only got live and neutral wires.

Any advise greatfully appreciated.

 

[Taylortwocities]

Is the lamp double insulated?
It should have a logo on it that looks like this

Untitled

• Taylortwocities
• 30 Sep 2009
• 4

 

[Alison556]

Yes, it is double insulated

 

[Taylortwocities]

OK, so it has been designed and made to not require an earth.

(I'm not sure if a touch lamp could work if it were actually earthed!)

I could not guarantee that would be safe if you - basically - redesign it by removing the touch sensor circuitry. Hard to be certain without looking at the thing.

 

[Alison556]

Touch lamps are a pain. It appears if the bulb blows, it knackers the thing completely. It happened with another one and I stuck an inline switch in (didn't touch the sensor or anything on that one) and it works fine (though I'll just have jinxed it and it'll probably blow up on me when I go to bed).

This one though is being temperamental. I did wonder if I could just remove the sensor and rig it like an ordinary lamp but thought I'd better check first.

I tried taking a couple of pics but I don't think they're much use.

From the touch controller, there's a black wire bolted to a metal brace, then a blue, black and red. The red from the controller is attached up to the blue from the flex and from the blue to the lamp holder.

The blue from the controller is attached to the brown to the lamp holder.

The black from the controller is attached to the brown from the flex.

Bet that doesn't make a blind bit of sense

 

[bernardgreen]

Bet that doesn't make a blind bit of sense

Yes it does

You can remove the sensor..

Connect brown from lamp to the brown in the flex

Connect blue from lamp to the blue in the flex.

Without looking at the lamp is it not possible to say for sure about the need to earth the metal base plate. The difficulty is the touch area has to be conductive so it must now be double insulated from the mains. The sensor connects the touch area via a resistor of several million ohms to the mains. It has to do this to be able to sense the touch. Without the sensor that connection has been removed and providing there are two layers of mechanically strong insulation between wires and the touch panel it should be OK without an earth.

 

[alan333]

I had the same thoughts when I rewired our pair of metal based touch lamps. I decided to play it safe and fit an earth anyway. I replaced all the internals with a hard wire to each side of the bulb, plus earth to the main metal ring where the bulbholder assembly was screwed to the base. I used cable like this..

http://www.screwfix.com/p/round-flexible-cable-2183y-3-core-0-5mm-x-5m-black/57458

I also used in-line switches from ebay.

 

[Astra99]

I have converted several touch lamps (which have failed, some with "shocking" results!) to in-line or switch-on-base switched. All have been rewired with three-core cable with the earth connection made to the base of the lamp.

From what I can see of the touch circuitry, it cannot work with the metal of the lamp earthed, but, in the event of a L-N or L-E fault between the circuitry and the lamp, the circuitry itself will fail rendering the lamp useless!

This circuitry affords a degree of protection, which is lost when rewired. Thus, an earth connection is then required. Oh. BTW it's a 3A (max) fuse in the plug!

 

[Alison556]

Thanks all.

Better go get myself some three core wire.