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We have an issue with our hall light where bulbs keep blowing. It's only this light that's having an issue. They are lasting a matter of days. We had a IKEA smart bulb in there for years then it went. I replaced it with a normal IKEA LED and have been through at least 3 of these in about 2 weeks. The most recent lasted a day! It could be duff IKEA bulbs but maybe there is more to it.
There are two switches controlling the light. To make sure the light was off, I removed the bulb then used my mains tester screwdriver on the contacts. I noticed that even when "off" the screwdriver is glowing slightly on the live contact. So the light is receiving voltage 100% of the time, but lower when (supposedly) off.
I've tightened the contacts on the fitting and even swapped the holder with another one. The bulb still blows. Potentially, it could be that the Smart bulb came to the end of its life and the normal IKEA bulbs can't hack the double switched arrangement?
Is a live being slightly live normal for a doubled switched fitting? Perhaps I just need to buy better bulbs?
You can get a ghost reading, even on an empty metal tin https://www.voltstick.com/how-to-av/videos-and-blogs/voltstick-false-readings
"You can get a ghost reading"
Even with an old school full contact voltage tester screwdriver?
You are seeing a ‘phantom’ voltage, caused by induction. The wires are long enough to cause this, there will be a 3 or 4 cored cable running between the two switches, one core of this will be permanently live, the other is a switched live and a neutral, as one is permanently live, it will cause a small induced current in the switched live cable when it is turned off. If you get a decent multimeter, especially one with a moving coil, you will not read any voltage, yes, there is voltage there, but it is so small that a good meter will not be able to read it, but the widowmaker screwdriver you are using can detect the slightest little current flwoing thorugh you. Yes, it flows through you, so chuck that screwdriver away and get a proper tester.
The actual switching arrangement makes no difference to the bulbs, you can hsve as many as you like in circuit. If you still have a voltage present then it could be an induced voltage due to how it’s wired and nothing really to worry about or maybe a contact in a switch not opening fully. Does a bulb glow slightly when the switches are off? As for them blowing constantly I assume it’s an eddy screw lamp holder? If so try bending the centre contact up a bit, they can sometimes not touch the lamp contact properly which causes premature failure.
Oh and bin the screwdriver! They work by making you part of the circuit and you’re one failed resistor away from a bad time
Yes, your bulbs are cheap , so get some decent ones. The chances of there being a fault on that one light fitting is minimal at best. Vibration can cause a loose connection, which isnt good for incandescent lamps (bulbs), but LEDs dont generally fail because of that. I worked in Social Housing for 2 years, I was called, probably every 2 weeks, to hosues where they say the lighting circuit was faulty, I’d go, and find they were buying a 4 pack of bulbs for 99p, and changing them every 2 weeks. Once I put a good quality lamp in, I never had to go back.
I understand now, the inducting of a current from another conductor in the cable makes sense.
The IKEA bulbs were £3 each! Any decent bulb recommendations? Philips? What should I be paying for a bayonet fitting, 60w equivalent LED bulb? The more I think about it, there's every chance these are a bad batch of bulbs. All bought recently in the last month or so from the same shop. IKEA lights are all screw fitting so they might not sell many bayonets....
Is the danger of the screwdriers not more that you don't know when they're broken? A resistor is unlikely to fail shorted but point taken. There are newer better and safer tools. Any recommendations for those too?
"Does a bulb glow slightly when the switches are off? As for them blowing constantly I assume it’s an eddy screw lamp holder?"
Not sure about the glowing... I'd have to sacrifice another bulb to find out. It's a bayonet fitting.
I've got this mains detector from Screwfix (can't post a link)
Fluke AC Non-Contact Voltage Detector Pen 1000V AC - Screwfix part number 85949
"Is the danger of the screwdriers not more that you don’t know when they’re broken?" and by this I mean it's broken so it doesn't light up, rather than broken and electrocute you.
Probably a good time to check your smoke alarms are in order too, sorry to be morbid.
Is there a dimmer on the circuit? When was the circuit last tested? What's the voltage like? A higher than normal voltage can shorten the life of a LED lamp, voltage spikes can also cause this.
Sometimes you can get crappy lamps that don't last.
Some more possible causes listed here.
https://www.wholesaleledlights.co.uk/blog/2021/12/15693/
Fluke AC Non-Contact Voltage Detector Pen 1000V
These things light up when you rub them on your wool jumper. Never use these to check if something is live/dead. There is a reason why we don't use them on site.
This is what we use in the trade. https://www.tester.co.uk/martindale-vipd138-s-voltage-indicator-proving-unit-kit
Old switches can damage LED lamps (especially IKEA ones). I had to change multiple switches that were 15 years old because they kept zapping the lamps they were connected to.
You'd normally prove on a known source before and after the isolation test, the Martindale tester linked ^^ has a Proving Unit included. I don't know if a battery would prove that your gadget worked, but it certainly wouldn't prove safety
You can get a ghost reading, even on an empty metal tin
Who sold you your multimeter?
Who sold you your multimeter?
Sam Wheat
You can get a voltage indicator for £20 from Toolstation. For DIY use it’ll be fine, as you can prove it on a working socket or similar. 230v shocks hurt even if through your hand. It also requires vigilance, as shocks are mainly due to complacency despite the person having the requisite test gear in their bag but not using it.
The reason neon screwdrivers are considered dangerous is not because of the neon (the concept is safe in principle), but because they’re vulnerable to water ingress. You don’t notice this, put it against the live conductor, and short directly to ground through your body.
Edit: £10.99 from Screwfix. Not enamoured by exposed probes but it’s £11..
https://www.screwfix.com/p/lap-ac-dc-2-pole-voltage-tester-with-rcd-400v/669HY?
“Is the danger of the screwdriers not more that you don’t know when they’re broken?” and by this I mean it’s broken so it doesn’t light up, rather than broken and electrocute you.
The basic ones with just a neon inside and a fuse are very reliable, but you should always check them on a known live wire first.
I also just touch the wire with the back of my knuckles as a secondary test, if live, your hand just recoils away from it. I might also add I have no fingerprint on my RH forefinger, when at the age of three I stuck it in a live light fitting which had no bulb fitted. I was rewarded with a penguin biscuit, which started a 50 year love affair with giving myself electric shocks...
Find out what the voltage is with a multimeter. Could be a wiring fault.
“I also just touch the wire with the back of my knuckles as a secondary test, if live, your hand just recoils away from it”
I tend to short stuff to earth. Also turn the whole fuse board off.
As stated above complacency will get you. Customer states no power to fused spur, test it with meter, sure enough it’s dead.
Customer switches downstairs light off, feed to fused spur becomes live whilst I’m holding on to it and leaning on the hot water tank. Some moron had wired a fused spur to the switch wire of the lighting circuit.
Very painful that one.
Had the same issue and posted on here a while back.
Was a bit flummoxed at first. But my issue was solved easily by simply replacing the light switch.
didnthurtFull Member
This is what we use in the trade. https://www.tester.co.uk/martindale-vipd138-s-voltage-indicator-proving-unit-kitPosted 23 hours ago
Username checks out.