Lightbulbs - the facts?

Probably... or use a combination of real bulbs and energy saving to keep above the threshold but reduce the total. This can also work well with multibulb fittings I find - you can use a few CFLs to keep the spaces populated and running costs down, while contributing some[1] light, but have a real tungsten one in there as well to give proper colour rendition ans usable illumination.

Cost and size? Maximum perceived light output seems to be the selling war

- not the quality of it. And given the quoted light output is just not in the same ballpark as most see from a GLS, it makes me wonder why they bother.

It's rather like the official MPG figures for cars. Pie in the sky. So only useful for comparing two similar products by anoraks.

Across the extended family, we have two rooms with dimmers.

There's an 18W halogen replacement, and I tried one. It was very noticably dimmer than the 25W candles, so I went to the next size up, 28W halogen. That's fine, so they've now all been replaced with 28W halogens. So far, none of the halogen replacements have died, and the increase in light output has been welcomed.

In this case, I wanted to reduce power consumption, mindful of the 300W of lighting, but the fittings/shades were very much wanted, and so I had to think of some way which retained them. I decided to convert them all to 12V halogens.

I made up five adaptors to convert BC to GY6.35 (bi-pin), so I could retrofit 12V capsule lamps, being careful to make them so filament position was the same as with the 60W candles.

The dimmable electronic transformers are mounted in a vented metal case in the room above (including additional self-resetting termal trips), but this required some rewiring, which was fortunately easily done as there's currently no floor covering in the room above (which was the reason for doing this now).

Two further considerations. 12V lighting will draw 20 times more current on the 12V side, so consideration needs to be given to the current carry capacity of conductors. Secondly, I want to be able to revert to mains lamps in the future without gaining access under the floor again, so any new cabling used will still be mains to allow reuse in the future.

The central light at 3 x 35W 12V will draw 8.75A which is within the capabilities of 1mm T&E, so I did try using the existing wiring, but with the expectation the voltage drop would be too high for efficient 12V operation, and indeed it was. So I swapped this for 2.5mm cable. What surprised me was this didn't make much difference - I was still losing too much in the cable - much more than I initially calculated, until I remembered the output is high frequency, and the skin effect. Didn't have any 4mm cable, so went straight to 6mm, and that worked fine, helped (from the skin effect perspective) by being multi-conductor. The 1mm cable seemed to be OK for the wall lights, one of which was directly below the transformer, but I did change out a length of the other one for

Anyway, this has been a stunning success. Unfortunately, I didn't actually measure the light level in the room before starting, but the 35W 12V halogen capsules produce noticably more light than the 60W 240V candles had done (although the halogen capsules are high efficiency type).

As of course was the first street lighting.

No one's been able to find out, because in double-blind tests, the claimed effects show no correleation with type of lighting.

There was certainly a measurable effect with poorly made linear tubes running at mains frequency which end up slightly rectifying and generating 50Hz or 60Hz flicker. But that doesn't apply to CFLs.

Of course, you can buy cheap CFLs with poor coatings and colour rendering, but they're actually quite hard to find if you stear clear of no-names.

Yes, after swapping for LEDs you'll need to change it to a brightener instead, but that doesn't exist ;-)

beware if running them at an angle. We have a load of these, and in the dining room they fit in a lamp at something like 45 deg. Similarly, another one fits horizontally. They fail really quickly - looking at them it seems the filament isn't supported well enough and it drops and breaks. The ones that are either in pendants or upright in table lamps are great and have lasted well.

Ignoring the fact that many of these give horrible light, you have to be careful using them with dimmers. Many dimmers (older ones anyway) have a minimul wattage to work reliably - they won't all drive dimmerable CFLs reliably.

Darren

I wonderhow much radio frequency interference all this causes if there are any folk with hobbies in the radio reception or ham area, you might otherwise become public enemy no 1! Brian

Try here for an expanded version of what you are saying

More to the point if using nuclear electricity a light bulb at 100% efficiency is similar to oil at 40-50p a liter pricewise and creates no CO2 at all.

The original dimmer (going back some years) did interfere slightly with MW or LW (can't remember which), but it was changed for an X10 DIN rail dimmer some 8-10 years ago as part of the home automation, and I don't recall getting any interference from that. I guess there's the potential for the 12V supply to generate some.

I'll try a MW or LW radio (if I can find one) and let you know. It certainly doesn't interfere with FM.

LED is getting there. Bought the pack of three LED torches on offer in Costco this month (=A312.58 inc VAT). Flippin eck they is bright. Quoted battery life (3 x AAA's) is only 4 hours on 50% but they are the best torch I have had for a long time. Single CREE LED, quoted at

You do have to watch the ratings though. I waiting for a LED GLS replacement to come along. Saw somthing the other day in Bean 'n Queued that was a clear GLS envelope with a rid inside covered with LED elements. Nearly bought one to try until I spotted the light output was only 100 lumen. They also had some other LED GLS shaped things but I think the light only came out of the rounded top not, more or less, in all directions, unsurprisingly these had an output around 500 lumen presumably on axis of the beam...

You would think there would be a commercial market for something like this that includes a small SMPSU in the base to facilitate use of 12V lamps in mains fittings. (I have seen commercial ones that take G9 mains halogen capsules).

Leeds branch of Clas Ohlson had the "LEDs on a PCB in a GLS" the first (and so far only) time I went in for a look around. Wasn't tempted to buy one to try though. Seemed like a convenience store for those who can't be bothered to shop around. 50cm SATA cable for £4.99 anyone?

In Detroit, the 5 D-cell Maglights are known as Malice Green lights, after a guy who was beaten to desth by cops using these. See:

--=20 Davey.

--=20 Davey.

They put out a heck of a lot of audio frequency interference.

My loop listener makes chainsaw noises if I walk past the lightswitch with a CFL turned on.

Owain

Yes, but I think it would be a difficult sell - people just don't understand lighting.

Someone (Philips, I think) did produce a GLS-like lamp with a LV halogen capsule and SMPSU in the base. The capsule was not changable, you chucked it all out when the filament (or SMPSU) broke. They were only available in rather low power ratings, probably because the heat from something like a 35W halogen would kill a SMPSU. I don't recall if they were dimmable either. They were very expensive and I haven't seen them around for some time now.

In message , Brian Gaff writes

Hence the expression "as dim as two Toc H lamps in series" (a favourite of one of one of my elderly works colleagues).

In message , Gareth writes

In that case it must either give out less light or less heat, and as pointed out elsewhere the heat given off reduces the demand on the heating system for most of the year., so they are only more efficient in summer.