UK Quinetic switch question.

[GLM1371]

Hi everyone my first post here. Quick background I'm a newly qualified installer of somewhat advanced years whose just starting out in the trade.

The reason I'm posting is because I've been having a puzzling issue with Quinetic light switches, I can't seem to get any sense from Quinetic technical support so I hoped I might get some here. The issue is this, six weeks ago I did some work re-wiring a client's lighting circuit and also installed a Quinetic in-line switch receiver, replacing a traditional 1-way 1-gang switch. Everything functioned as expected and the circuit test results were good, minor works cert, job done.

Last week I got a call from the client complaining of strobing from the bulb, and when he changed bulbs, the new bulb briefly powered on even though the switch was off. I went round and did some testing. I connected my MFT to the pendant with an adaptor and got a reading of 238v regardless of whether the switch was open or closed. I plugged the bulb back in and tested around the pendant with my volt stick, which indicated voltage present when the light was off.

I got in contact with Quinetic who told me it must be a faulty unit. I got a replacement this week and tried it on my own lights. Same result. I consulted the regs and came across regulation 537.3.1.3 which mentions a semiconductor device may control current without disconnecting the poles so I put my clamp meter around the switch line and operated the switch, sure enough 0A with the switch open and 30mA with the switch closed. I was still worried about the voltage reading from the outlet though and a new communication from the manufacturer read "no, the voltage is switched" which wasn't terribly helpful.

Please can one of you experienced gentlemen throw some light on this for me? Has anyone else installed one of these and had voltage at the lighting point with the switch off? Have I just been unlucky and had two faulty units? Or is there something I don't understand? Any help and answers greatly appreciated.

Gary.

(footnote:- just remembered that semiconductor devices can't be used for isolation so that rules that out).

 

[Mike Johnson]

Never had a problem with any of mine, but as far as I can remember the power unit is polarity conscience, just a thought.

 

[loz2754]

What's the model number of the receiver?

 

[GLM1371]

The model is the QURS1W in-line receiver switch.

 

[SparkyChick]

The key point here is this:-

• The RS1W receiver switch only works when you have a live feed in and a live feed out.
• No neutral is required

For the device to work it must pass a current through it to generate the voltage it requires for the control circuitry. Whilst it is a tiny current, it is still enough to make LED lamps glow or strobe. You can get snubbers that prevent this (I've looked into them in the past when a client replaced his halogen lamps with LEDs and all his random on/off security switches stopped working).

This thread may offer some advice.

Advice (please) regarding suppressor / "snubber" for LED lighting

Hi all Hoping someone might be able to advise. I've got two sets of LED lighting this is affecting. One is the plinth LEDs I originally raised a thread for some months back; one is two LED wall lights. The problem I have is that, when the lights are off, they flash briefly every ten seconds...

www.electriciansforums.net

 

[GLM1371]

Thanks for the reply SparkyChick. I hooked up the unit per the instructions just like a normal 1 way switch i.e L and L1, permanent line and switch line, definitely no neutrals involved. What's puzzling is the reading of 238v at the pendant which is constantly present no matter what the switch position. This brings about a situation where the bulb is not lit yet my voltage detector is howling like a banshee which obviously isn't what you'd normally expect. I've emailed all this to Quinetic and they've yet to reply.

 

[SparkyChick]

The 238v is present at the pendant because the unit passes a voltage through itself all the time. The power supply used to supply the receiver and switching circuit in the switch module has to do this so that current is passing through it... current has to be able to flow to be of any use so it has to apply power to the pendant because that's it's neutral connection. I don't understand how they work, I just know this is one power supply approach that is used for electronic switches that don't require a neutral.

The reason the bulb isn't lit but the voltage detector howls is because the switch is limiting the amount of current flowing. It may need only a few milliamps to operate which is unlikely to be enough to properly light a lamp, but the voltage being present generates an electric field that the voltage detector is picking up.

 

[GLM1371]

That exactly tallies with my results. The unit is clearly switching current on and off whilst the voltage somehow remains constant. I suppose the 64 million dollar question is "is this safe?" It's somewhat disconcerting to turn off a light switch and then go to change the bulb (as my client did) knowing that a reading of 238 is present at the open socket, surely this is an available potential difference? Or is it some kind of "phantom" voltage that's quite safe. So far I haven't found anyone willing to stick their finger in to let me know, and I've had no reassurance from the wholesaler or the manufacturer.

 

[Mike Johnson]

Silly question, but have you paired the switch to the receiver unit?

 

[GLM1371]

It's one unit Mike the receiver is integral to the switch, unlike a normal kinetic.

 

[Mike Johnson]

It's one unit Mike the receiver is integral to the switch, unlike a normal kinetic.

Ah OK I know nothing about that type, good luck.

 

[Avo Mk8]

That exactly tallies with my results. The unit is clearly switching current on and off whilst the voltage somehow remains constant. I suppose the 64 million dollar question is "is this safe?" It's somewhat disconcerting to turn off a light switch and then go to change the bulb (as my client did) knowing that a reading of 238 is present at the open socket, surely this is an available potential difference? Or is it some kind of "phantom" voltage that's quite safe. So far I haven't found anyone willing to stick their finger in to let me know, and I've had no reassurance from the wholesaler or the manufacturer.

I believe the quiescent current of the receiver switch is < 5mA.
That means it's roughly equivalent to a 47k ohm resistor (worst case) connected across the open light switch, as it were.
So if you measure the voltage across the lamp holder, a multimeter of many megohms impedance will show close to full mains voltage, which is what you saw.
I'm not going to volunteer to do the finger test, but given the current is limited to a few mA, it's unlikely to be life threatening.

I would say all the results you describe in your first post are normal artifacts of the design of Quinetic switches. Quinetic do warn that their products do not work with all led lamps, and it's unfortunate that the client's lamp responded as it did. As mentioned above, a 'snubber' across the lamp should solve the problem.

 

[GLM1371]

Ah OK, that makes sense. Thank you Avo.