Vintage light bulb

[ppppenguin]

About two thirds of the way down this page is a photo of a 230V, 150W bulb marked "Property of HM Government". Found in a long lost passge in the Palace of Westminster.

https://www.bbc.co.uk/news/uk-politics-51630630

Interesting to note it's 230V, from the days when mains was 240V.

[alanworland]

Interesting! Government light bulbs, perhaps to deter theft?
My Dad purchased a fair quantity of 60 and 100 watt light bulbs years ago that were marked 250v - the idea was that as they were under run they would last a bit longer, don't remember him saying 'they were doing well' but the theory was good.

Alan

[ppppenguin]

Before the mains was standardised at 240V 50Hz there were many different voltages and frequencies in use. Presumably Osram and others made lamps to suit the different areas.

The relationships between voltage, light output and lamp life are very steep curves. At one extreme you can underrun a lamp by not very much and it will last almost for ever. At the other you have photofloods, heavily overrun and lasting just a few hours.

Wasn't the shiny "Bronco" toilet paper in government buildings also marked as property of HMG? Or is that urban legend?

[Kalee20]

The relationships between voltage, light output and lamp life are  very steep curves. At one extreme you can underrun a lamp by not very much and it will last almost for ever. At the other you have photofloods, heavily overrun and lasting just a few hours.

Which makes me think - optimising cost of photons!

At very low voltages, light output is very low, life of bulb infinite so can be discounted - but the lumens per watt is low. So lumen-hours per £ is low.

At high voltages, the tungsten lamp becomes much more efficient, so lumen-hours per £ of electricity gets much better - but the short bulb life can't be discounted. Particularly if labour cost of replacement is included. So overall financial efficiency is low again.

Somewhere in the middle, there's an optimum, but has anyone ever studied it and arrived at a conclusion (preferably in form of a graph)?

[ppppenguin]

In the end of the era of GLS lamps, the lamp cost was tiny compared to the electricity for anything over 25W. Our USA friends had an advantage because of lower voltage. Thicker filaments allowed them to get more light output for a given power and life. Eg a 100W, 1000h lamp was 1330lm here, 1600lm there.

Now a 1520lm LED uses about 13W, lasts 25000h and costs about £7. That's about £1.80 per 1000 hours. Still dominated by the electricity cost. A GLS 100W lamps would be about £12.50 per 1000 hours, almost all in electricity.

[Nick]

A good rule of thumb used to be that "a watt for a year is a quid"...

At 16p a unit now, that's gone up to £1.40

[ppppenguin]

Like Nick, I use £1 per watt per year for rough calculations.

I think I aimed a bit low. and used about 12.5p/unit for my sums. I'm paying 14.36p/unit at the moment. In just over a month when my current fixed price, fixed term agreement is close to its end I'll be doing another price comparison using the Moneysaving expert service. This is good because it shows the whole market by default. Assuming prices remain unchanged betweennow and then I expect to be saving over £150/year comapred to my present tariff. No point in leaving now as as there are early exit charges.

If I was switching now I'd use Ovo where the electricity price is 13.3p/unit. My DD would go down by about £12/month and there's a £25 switching bonus. I might even conceivably stay with my existing supplier (EDF) as their new 1 year fix is the same price as Ovo. I don't think I've ever stayed with a supplier for more than a single fixed term. Loyalty is usually penalised these days.

[Mike Watterson]

Our USA friends had an advantage because of lower voltage. Thicker filaments allowed them to get more light output for a given power and life. Eg a 100W, 1000h lamp was 1330lm here, 1600lm there.

I think that's not always true. Or maybe never true. The lumens per watt for tungsten, and the colour temperature, depend on the gas in the bulb, the filament construction and the operating temperature.
Also some 100V - 115V lamps use different construction to 220-240V lamps, apart from the base. Curiously the European ES is supposedly 1mm larger than USA version. I read France and Greece used to use the 22mm BC of UK and all former British Territories.

I note B&Q are selling BC to European ES adaptors. Any comments?

IMO these are the best non-filament lamps yet since CFL and tubes went to Electronic Ballast. ZERO RFI and the decent ones have the best colour rendition I've seen apart from halogen. Don't confuse with Colour temperature.

https://en.wikipedia.org/wiki/LED_filament

They may be longer life due to not having an Electronic PSU/ballast to fail and lower LED temperature?

The lowest power are available with half as much power in USA.

[Refugee]

I have been using those filament bulbs and they have been reliable.
I know there is not a lot in them as they have only got a small ES base on them that looks the same as old tungsten types.

[Kalee20]

IMO these are the best non-filament lamps yet since CFL and tubes went to Electronic Ballast. ZERO RFI and the decent ones have the best colour rendition I've seen apart from halogen. Don't confuse with Colour temperature.

https://en.wikipedia.org/wiki/LED_filament

I think so, too.

I have not taken one apart yet (have 3 in use and none has failed yet in coming up 3 years) so I don't know how the current to the umpteen LED's is controlled - but they are LW/MW friendly!