Touch sensitive lamps - and metal housings not connected to earth...

[Aesgarth]

I'm trying to make a touch sensitive lamp, but I'm running into a bit of an issue - the touch sensor box works by having a single wire connected to the body of the lamp, and works fine, unless the metal body is also connected to earth. I was under the impression that metal housings containing electrical wiring HAD to be earthed. I have checked with a commercially available lamp and it is not earthed - in fact it uses a 2 core flex, yet has a metal body...

A very quick google suggests that if it's a class 2 appliance (double insulated) then this is OK... I always double insulate my wiring anyway but I thought earthing the housing was still necessary.....

Any opinions on the matter?

 

[mtt.tr]

depends if its double isolated and the circuitry is properly protected then should be fine

but not easy to achieve at home

 

[Aesgarth]

Hmm. Double isolated is easy - and something I would do anyway... Checking the circuitry on the other hand is less easy.

 

[brightspark]

what do you mean you double insulate things .class 2 does not need an earth to a metal frame if it is fitted with a none metallic lamp holder 2 core is fine. if a steel or brass one fitted it must be earthed https://www.intersafe.co.uk/news/What-does-Class-I-and-Class-II-mean-when-it-comes-to-PAT-Testing/ a lot of new led ceiling lights are metal that are class 2 and don't need an earth

 

[mtt.tr]

what do you mean you double insulate things .class 2 does not need an earth to a metal frame if it is fitted with a none metallic lamp holder 2 core is fine. if a steel or brass one fitted it must be earthed https://www.intersafe.co.uk/news/What-does-Class-I-and-Class-II-mean-when-it-comes-to-PAT-Testing/ a lot of new led ceiling lights are metal that are class 2 and don't need an earth

not sure id trust a diy attempt at class 2 with a touch sensitive element unless the part are bought as intended and not modified

im imagine this sort of thing being used as is unboxed

https://www.amazon.co.uk/Lamp-parts-incandescent-bulb15W-80W-230V-240V/dp/B00E0CTVGS

 

[brightspark]

if the mains wiring to it is put in an insulated box and as I said it has a plastic none metallic lamp holder 2 core is all that is needed no earth

 

[mtt.tr]

if the mains wiring to it is put in an insulated box and as I said it has a plastic none metallic lamp holder 2 core is all that is needed no earth

i wasn't suggesting earthing it, i was more making the point of unless you know what you are doing probably best not to.

im sure we have seen our fair share of horrors such as the loft light that is nearly always on speaker wire

 

[rtbcomp]

I'd be worried about mains finding its way to the touch plate, rather than through the frame &c.

 

[mtt.tr]

I'd be worried about mains finding its way to the touch plate, rather than through the frame &c.

frame is the touch plate

 

[Aesgarth]

what do you mean you double insulate things .

I mean that on everything electrical I've made so far I've made sure there are at least 2 layers of insulation between the live/neutral cores and any metallic element of the frame/body. I also earth said frame/body.

class 2 does not need an earth to a metal frame if it is fitted with a none metallic lamp holder 2 core is fine. if a steel or brass one fitted it must be earthed https://www.intersafe.co.uk/news/What-does-Class-I-and-Class-II-mean-when-it-comes-to-PAT-Testing/ a lot of new led ceiling lights are metal that are class 2 and don't need an earth

I'm using plastic lamp holders but the main body of the lamp is metal. previously I've used a remote dimmer switch and Zigbee bulb - see the lamps in this thread:
https://www.mig-welding.co.uk/forum/threads/bedside-table-and-lamp.89344/

not sure id trust a diy attempt at class 2 with a touch sensitive element unless the part are bought as intended and not modified

im imagine this sort of thing being used as is unboxed

https://www.amazon.co.uk/Lamp-parts-incandescent-bulb15W-80W-230V-240V/dp/B00E0CTVGS

That looks very similar to the module I'm using, albeit with different coloured wires. I'm using it unmodified but to make this work I think I'll have to put the whole thing inside a plastic junction box inside the body of the lamp - I should have room to do that - since the wires coming out of the sensor module only have a single layer of insulation. However I may stick to the remote solution as I trust that.

frame is the touch plate

This, The idea is that the whole of the lamp is the touch plate. I was hoping I could also earth the body of the lamp but that stops the touch sensor module from working.

I have access to an insulation tester so I can test that the body is insulated correctly but the whole setup seems less safe than I'd like.

 

[grim_d]

i wasn't suggesting earthing it, i was more making the point of unless you know what you are doing probably best not to.

im sure we have seen our fair share of horrors such as the loft light that is nearly always on speaker wire

My loft light is on two 4 way extensions on an uninsulated choc block to 2.5mm straight into a MCB in the CU.

No it wasn't me...and it's far from the worst thing I've seen in this house!!

At least the cross section of the wiring is adequate.

 

[Wallace]

It just so happens a chap at work asked me if I could repair his touch sensitive bedside lamp, like you say there is no earth and two core cable with plenty of metal in the lamp framework.

The PCB looked hot and bothered so I ordered one of the generic switch units off eBay from a UK seller and fitted it yesterday morning. It works well but I’m not keen on cheap mains operated Chinese kit so I ran some tests to see how hot the plastic fire hazard would get and I’m not happy with the heat generated on standby. I will test the current draw today then ask him if he is happy to use it or wants a switch fitting which I would be happier doing.

 

[Aesgarth]

I think on that basis I'm going to give up on this idea and stick to the remote switch I'm comfortable with, at least for the moment.

The heat is an additional concern... While I can't see any way for the lamp I'm making to catch fire itself, even if the plastic parts inside get hot enough, I'm concerned about heat dissipation for the board and the lamp itself getting hot.

Oh well. Back to plan A...

 

[mtt.tr]

I think on that basis I'm going to give up on this idea and stick to the remote switch I'm comfortable with, at least for the moment.

The heat is an additional concern... While I can't see any way for the lamp I'm making to catch fire itself, even if the plastic parts inside get hot enough, I'm concerned about heat dissipation for the board and the lamp itself getting hot.

Oh well. Back to plan A...

Look at an or sensor just wave your hand over it

 

[Aesgarth]

Look at an or sensor just wave your hand over it

I'm guessing that's optical? In which case not ideal for the application I have in mind since the lamp body will appear to be a solid chunk of steel.

 

[mtt.tr]

I'm guessing that's optical? In which case not ideal for the application I have in mind since the lamp body will appear to be a solid chunk of steel.

Ir spell checked

 

[mtt.tr]

https://www.simplelighting.co.uk/ca...=41a8698ef12467cc1d89c835f3b20083&fo_s=gplauk

 

[Aesgarth]

Definitely something to consider thanks, although still a no for this project, as it would need a hole in the lamp body. I'll certainly keep it in mind for the future though

 

[roofman]

Reading all the concerns and associated risks with touch sensitive on a lot of stuff is anyone else asking "whats wrong with normal switches"? sounds another classic case of something designed to make life easier and is in fact making it harder..like those bedside tea maid machines

 

[brightspark]

Reading all the concerns and associated risks with touch sensitive on a lot of stuff is anyone else asking "whats wrong with normal switches"? sounds another classic case of something designed to make life easier and is in fact making it harder..like those bedside tea maid machines

I used to repair goblin teas made fit new elements in the kettle and renew the clock motors 30 years ago