Design voltage of incandescent lamps

Could try and speak to company like JCC and see what they have to offer.  Realistically you need to match the lamp and the dimmer to get the best effect. 

I have used a low wattage transformer for 12-18V as an autotransformer to prolong the filament life in such case - primary on the mains, of course, and the secondary in anti-series (opposition) to the mains, to give mains in less the secondary  voltage.
Its smaller/ easier than the variac, and less heat than the resistor.

Though a resistor may be better in some ways as it actually limits inrush too.

M

Yeah I'd rather an LED but when you've got a lamp that's got an older dimmer then the electronics need current flow through it - because there's no neutral connection in the dimmer. So unless I do something radical I can only use incandescents - or halogens.

Even if I replaced the dimmer, dimmable LED's operating of mains are just embarrasingly poor - especially for a reading lamp. Maybe I'll wrap some dim to warm tape around a tube and install a driver. But that would probably look very heath robinson.

I can't be the only person with this problem - it's clearly widespread and has been for over a decade - but nobody can find a good solution.

Which is why where things really matter, we often have the equivalent of incandescent lamps longer than you might like, such as a telephone standard with voltages and current levels based on carbon granule microphones and moving iron earpieces, with complex electronics at both ends emulating the original kit. Or, if it is a railway telephone, sometimes the actual original kit.

Mike

The Designers will need to work on it longer until

it is fit for purpose and fit for peer review.

Too many products come to Market before they are ready for the Market.  eg AFDDs

Amazon/ebay/Temu are remote selling into the UK and a lot of the products sold do not meet a BS or BS EN standard.  Some may say they are selling poor quality items.  If you are looking for lamps for the home Ikea are quite good quality and units last a fair while.  Another point to note is an incandescent is totally electrical where as an LED is electronic. 

A formal answer to you question.

BS EN 60432-1:200+A2:2012 is the standard for incandescent lamps.

2.2.1 Mandatory markings requires that lamps are marked with their rated voltage or voltage range [this raises obvious question's which aren't addressed in the standard but let's assume nominal within range], and the rated wattage.

But there's a national departure in the BS version "The rated voltage marking for lamps intended for use on United Kingdom supply voltages may be 240 volts or 240 V." so you need to check the datasheet.

This standard is for domestic and similar general lighting. Specialist lamps will have their own standards. But I think it's particularly interesting on bulb life - I have a reading lamp which needs an incadescent because LED's don't pull enough for the dimmer. As I can no longer buy bulbs at retail I've been getting them of a popular website named after a river in South America - and they don't last two seconds probably rated for 230V. I think I might try using a variac.

It's all very well that a person knows the difference between these states.

But you've got do design a machine that knows, and meets a SIL rating. What happens if the visible front of a lamp appears off, but the monitoring equipment which can only see current and voltage doesn't see this? That's not too difficult if you're on a clean sheet design, but if you've got an existing mature design then it's not something you can just change.

Safety engineering is very hard work unfortunatly.

To me it seem quite obvious that LED used for outdoor like the following

Traffic signals

Runway lamps

Railway signals

should fail to safe. If they don't then there is common sense lacking and the design team need to be re-educated as to what the failing are.  As you say Strobe, which is annoying enough on a garden PIR floodlight but it is absolutely dangerous for a traffic signal or a run way at night in the rain (just adding risk to emphasise the point for future readers) I would then also go 1 step further


Get that unit to report back to central office for traffic signals or rail signal or control panel at an airport of its failure.  Designers need to make kit that is fit for purpose and fit for peer review.
UK traffic lights could be fitted with IoT technology quite easily.

The airport would also get further enhancements like secondary/redundancy light sets.   

Sergio Fernandez said:

As for the Manufacturer who make Traffic signals using incandescent lamps they need to speak to their R&D and get working on the LED version.  The cost savings for whoever pays for the street sign / Traffic signals pence/kWh should be a convincing factor.  100w lamp vs 15w LED Lamp.

The failure mode for most LED lamps is often to a stroboscopic output as opposed to off.

I’m sure there are LED traffic signals – I presume they’d need a bespoke driver so can’t be easily retrofit. I’ve got a client who manufactures railway signals with LED’s, and a former one who manufactures LED runway lamps. Both are subject to very stringent requirements so that they fail to a known safe state.

Incandescent lamps are a lot easier on this front – their failure modes are more obvious. If the controller detects an open circuit then it knows there’s a fault and can degrade into the safest state which in most cases is to trip all signals such that motorists will interpret as caution and give way.