Ikea light - what is this for?

eidolon · 19 Apr 2018 at 12:49

Im just looking to fit a new Ikea light and noticed this thing. Looks like a capacitor or something?
Do I need it? None of my other lights have one. Can I just cut it off? (the cable is way too long so it would be neater if I could cut it off)

https://imgur.com/a/2nvS1n0

Swanster · 19 Apr 2018 at 19:47

Maybe it's an ntc thermistor? (guessing a bit)

rexehuk · 19 Apr 2018 at 19:58

That's a capacitor... as far as I can tell anyway, or it's a blob of coloured glue!

I'd imagine it's there for a reason.

Rroff · 19 Apr 2018 at 20:06

I'm going to assume it is this:

the capacitor acts as a controlling impedance thus dropping voltage and controlling the current through the LEDs. And, because the voltage across the cap and current through the cap are always 90 degrees apart, the capacitor does not theoretically dissipate power. resistor dropper would generate heat because voltage and current are in-phase.

Pretty horrid way to do it if that is the case but probably kind of necessary that it is there if it is used in that way.

eidolon · 19 Apr 2018 at 21:50

I don’t understand why it’s there though, I’ve never come across it on any other light.

steve bee · 1 Jun 2019 at 19:11

I know this reply is rather too late to be of much use, but the device is an HR250-080 PTC thermistor. It will only carry about 80mA without tripping. I assume that it's there to prevent a lamp of more than about 10W being used in the fitting. That would preclude most incandescent lamps and ensure that only low-wattage CFL or LED lamps are used. It is probably there to protect the luminaire from excess heat, or to comply with some EU regulation about maximum energy consumption.

GeX · 1 Jun 2019 at 21:35

steve bee said:
I know this reply is rather too late to be of much use, but the device is an HR250-080 PTC thermistor. It will only carry about 80mA without tripping. I assume that it's there to prevent a lamp of more than about 10W being used in the fitting. That would preclude most incandescent lamps and ensure that only low-wattage CFL or LED lamps are used. It is probably there to protect the luminaire from excess heat, or to comply with some EU regulation about maximum energy consumption.

What a fantastic first post, thank you

hyperseven · 1 Jun 2019 at 22:29

steve bee said:
I know this reply is rather too late to be of much use, but the device is an HR250-080 PTC thermistor. It will only carry about 80mA without tripping. I assume that it's there to prevent a lamp of more than about 10W being used in the fitting. That would preclude most incandescent lamps and ensure that only low-wattage CFL or LED lamps are used. It is probably there to protect the luminaire from excess heat, or to comply with some EU regulation about maximum energy consumption.

There's me thinking it was just a Chinese Wifi packet sniffer