Are your LED light bulbs failing too soon?

A quick look at the reviews on the Amazon site would have put me off Megaman Modo lamps.

Which? did not test this type but another Megaman lamp performed well last year.

Quite so. Another case of a solution looking for a problem.

After around a hundred years of electric lighting starting to come into ordinary homes most people are smart enough to have cracked the problem of how to turn the light off after they’ve gone to bed. Of course, it was so easy to blow out the candle and today’s people need a similarly simple solution. The only drawback I can see to this device is the need to find your smartphone in the dark when you want to switch the light on again. There is also a slight risk that turning off one light could accidentally turn off the one in the bathroom where someone else is still up – or does each one have a unique signal that has to be programmed into the smartphone? Another thing to contend with.

We’ve just bought a nice pair of bedside lights – and you can switch them on and off without leaving the comfort of the bed or trying to find the phone!! Alternatively, people could go to bed with Alexa: “Switch off the light please and play some soft music. Night, night.”

Sweet dreams.

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And what happens when hubby goes to the pub with his smart phone and app, and the lady of the house needs to turn on the lights? Perhaps a phone call to the saloon bar will elicit the necessary instruction?

Thanks Duncan. It seemed odd to include a DC to DC converter but I can see the point and they are very efficient. I expect that colour changing LED lamps will prove increasingly popular and that ones that can be controlled from a phone will provide a relatively inexpensive way of adapting a home to meet the needs of old and disabled people.

I wonder how much thought has been given to the security of these devices.

duncan, I’ve never considered an LED bulb (nor a CFL) as a repairable item. You’d have to ensure they were not put in lights where they might get too hot.

No, but it can be interesting to dismantle failed bulbs to find out which component failed.

You can buy light switches operated with a remote control as well.

Both wall switches and ones for table lamps etc. When I was a young man I built a sound activated switch using germanium transistors from old computer circuit boards, which were cheaper than new transistors.

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I think for standard light bulbs ES E27 screw caps were a better bet than B22D bayonet caps. They were secure (could be used with a vibration proof lampholder where The larger (E40) versions were widely used in industry, street lighting and the like. Although, for some strange reason, the Europeans were slightly bigger than the American’s who used E26 and E39 (unusual for the Americans to have something smaller than the rest of us 🙂 ).

However, BC capped lamps were useful in many situations. For example they could position a lamp accurately where that was needed – car lights for example – and the lampholders could be designed to only accept specific bulbs.

I hate lamps with screw caps because they can become loose (which is why the motor industry stopped using them) or jam – common with oven lamps.

Duncan – it was probably the heat from old fashioned bulbs that damaged your bakelite lamp holders.

The vast majority of street lights were (many still are) equipped with screw lamp holders for E27 and E40 Edison screw lamp caps. They are subjected to continual vibration – low and high frequency – and did not come loose. Nor did they become stuck.

I’m not sure what relevance street lights have to household lamps. This information is from Wikipedia and refers to the vibration and jamming problems I mentioned:

Screw bases have a number of disadvantages compared to the bayonet fit type:

– The metal screw itself forms one of the contacts for the circuit. If the lighting system is not correctly wired, or a lamp is plugged into a non-polarized outlet, the metal screw can become live, presenting an electric shock hazard to anyone attempting to change the lamp.
– It is possible to over-tighten the screw, risking breaking the bulb or separation of the glass envelope from the metal base and leaving the base in the socket, especially when subsequently attempting to unscrew it.
– If the lamp becomes loose in the socket due to vibration or under-tightening, it can lose contact with the center contact and stop working until it is tightened. The bayonet type is resistant to vibration and much less likely to become loose.
As the metal thread carries current, any arcing can jam the thread.
– Corrosion is more likely to jam a screw thread than a bayonet fixing.
– Screwing in and unscrewing the bulb places more force on the glass envelope.[citation needed]
– When fixing anything with a cable attached, the cable will twist as the screw is turned.

Screw bases have a number of advantages compared to the bayonet fit type:

– Screw bases are more suitable for small size bulbs
– A bulb fully screwed home is more secure than a bayonet fit bulb
– Moisture and debris are less likely to contaminate the contacts of a screw base bulb
– Spring contacts are not necessary on screw base bulbs (the spring tension must not only ensure a good contact but it must also hold the bulb securely in the bayonet so there is a compromise)

Oops. What I have copied and pasted from Wikipedia has activated the Which? profanity filter. S******g is the opposite of unscrewing. It’s a crude alternative to bayonet cap lamps.

As I explained above the point about street lights is that they are under far more arduous conditions of vibration and potential corrosion than domestics lights. Experience there is very relevant. They generally have far bigger contact areas than B22d. Find me a modern HID lamp that has a BC cap. They are subject to high current ( up to 19A for a 2kW) for example, and high starting voltage pulses – several kV. Screw caps are suitable for these extreme applications (compared to the domestic environment) so I’d suggest they’ll be OK at home, as most of the rest of the world finds.
,

Street lights are a different product and use heavier glass and probably different metals/plating. Screw threads jamming is well understood from an engineering perspective. I recommend a trace of high temperature silicone grease to prevent oven lamps jamming.

Wonder how many words would get through were we to do a post on fitting E27 light sockets into a Hen house /storage shed where some excavation of the underlying medium-grade metamorphic rock was needed while warning of the dangers of sharp pointed vegetation?

🙂

The lamps are constructed in the same way – I have been associated with a lamp manufacturer and a maintenance company so simply pass on direct experience for the benefit of anyone watching. Make of it what you will. 🙂

Just look at the lamps in your home and you will see that some are plated and some are not. That can make a big difference. I think we had better agree to differ.

🙂

At first I disliked the continental screw caps on lamps as they were bulky and made the lamp-holder/shade ring combination complicated. It was my biggest gripe about IKEA when they first opened here. that all their lighting required screw cap lamps.

I had noticed that the light-bulbs in my school and various workplaces had screw caps and presumed that was to prevent pilferage; however, those in the old railway carriages had bayonet caps – but they ran on a different voltage and were fairly dim so not very appealing to pinch.

In the 1980’s, I think, table lamps and standard lamps started to appear with screw cap lamps so it was necessary to have a stock of both types of bulb. The Small Bayonet Cap [SBC] and the Small Edison Screw [SES] cap came along for smaller fittings, wall lights, multi-branch ceiling lights and other lower wattage applications. It was a good way of ensuring that bulbs would not be too hot for the smaller shades. I found that the SES types made a more positive connexion in the small lamp-holders.

Eventually, moving home a few times and replacing light fittings meant that there was little choice as most of the types we liked had the smaller bulbs and required screw caps.

Compared with the bayonet fittings I found the screw caps more secure in the lamp-holder, the lamp-holder was not prone to distortion or damage to the L-shaped openings that held the bayonet pins in place, there was no need to apply pressure against springs in order to fit and remove a bulb, and they do not have projecting pins that can get bent of broken off. I have had more trouble with bayonet caps getting stuck in a lamp-holder or the glass envelope breaking away than with screw cap lamps [necessitating shutting off the power and trying to extricate the parts with long-nosed pliers].

We still have some large ceiling lights that require bayonet cap bulbs but since they now have LED’s bulbs in them the need to change the lamps will be much reduced. I still have a large stock of incandescent bayonet cap lamps, including up to 150W, but I can’t see any further need for them now. I don’t suppose charity shops are allowed to sell them – perhaps the next time a friend of mine does a car boot sale I can hand them over and see if there are any takers.

I have a few 150s too – and a rig to put them in parallel – for rejuvenating capacitors – use the rig as a safe PTC thermistor – start off with a single 25W, then a 40, then 2 x 25, then a 60 – then a 100 – then a 150, then 2, then 3…..

One reason for the use of bayonet-fitting light bulbs is their resistance to vibration – screw cap lamps can loosen on, for example, vehicles, machinery and so in. Another is they allow lamps to be positioned correctly when their orientation in a fitting is important. The railways often used 3-pin bayonet fixings to make pilfering unprofitable – not usable at home. BC lamps make an automatically reliable electrical contact, whereas for screw caps you have to ensure they are fully screwed home.But for most domestic applications I’d suggest screw caps are marginally better.

Regarding contact reliability, surely a sprung holder centre terminal on ES fittings would overcome a lot of such issues with mechanical stop being the ceramic part against the holder. Also, is the ES thread start position not sensibly defined to ensure consistent orientation for bulbs that are not fully rotationally symmetrical (qv Practika/Pentax K lenses)?

Reliable contact does require the cap to be screwed home. The lampholder contact is slightly sprung, but it is possible to insert a lamp without proper contact. I was drawing the distinction between a design assuring full contact assuming a properly-functioning lampholder) and one that does not.

Where lamps require accurate positioning, as for example twin filaments in vehicles, the bayonet design assures this. So do other designs – like a flange support. A screw cap can allow electrical contact without guaranteeing position.

Thanks Ian. As far as I know, domestic users pay for kW rather than kVA, unlike commercial users, but that might change. An easy way to check the power factor of lamps is to use a table lamp connected to an inexpensive plug-in energy monitor that displays the power factor (or both kVA and kW). GU10s (as used in downlighter) are harder to check because these cannot be tested using a table lamp.

Power factor should be as close to one as possible (as it is for old fashioned bulbs) and can sometimes be found from the specification. I don’t believe I have any lamps with a capacitive dropper but I guess the PF would be well below 0.5. Capacitive droppers can be reliable but only if you use decent capacitors. It is cheaper to cut corners. 🙁

Ian – I don’t know whether your Meridian lamps are produced by the same company as this one, which looks respectable and produces commercial lighting products: http://www.sld-london.co.uk/files/sld-catalogue.pdf

As the owner of both a GU10 table lamp and a power meter, I can report that a randomly selected LED lamp uses 2W but 10VA. The CFL lamp normally used there used 8W at 16VA.

Thank for the figures. I tested a 5.5W Philips GU10 (bought in 2016 rather than current) and measured 6W and 8VA, so a power factor of about 0.75 compared with 0.2 in your case. (I doubt my meter is accurate at low loads.) The figures for your CFL, giving a PF of about 0.5, seem about right from what I can remember.