Fluorescent lighting

[Weatherlawyer]

Is there a wiki on how to install fluorescent lighting

[Brian Gaff]

Could one ask why you would want to these days, assuming you could find any to install!

Even I managed to install the old type, you just screw them up connect them up and they go! Brian

[tabbypurr]

Screw the in place, connect the cable up. The only gotcha is don't run the cable over the hot ballast. But why use fluorescent now? It's mostly obsolete.

NT

[Dave Plowman (News)]

Is it that far behind LEDs etc in terms of efficiency/life?

A florry gives a more even illumination than a series of LEDs.

Also a better selection of colour temperature, etc.

[whisky-dave]

I've heard they are, but not having testd them myself I can't say.

That's not really true espeacily over time, the ends of florrys go black and start to flicker and get dimmer with time.

Not sure that is true, but it should be difficult for LED tubes to be desined like the phillips hues.

We have new LED tubes in our new lab auto on and off, in my office they are also dimmable unlike the florrys in my present office, one of which is just flickering. One in the corridor is flickering and making a noise. It could wake the students up ;-)

[charles]

Dimmable fluorescent fittings have been around since the early 1960s. Nothing new there.

[tabbypurr]

the thin fls are very good, but don't perform ok if the room's cold. LEDs have overtaken general purpose T8s in efficacy.

not significantly. LED tape can be run anywhere, generally giving better illumination.

RGB LEDs give way more colour temp choice. Whites are more limited.

NT

[tabbypurr]

I used to spend time somewhere with magnetic ballasted fluorescents on 1930s variac dimmers. It worked.

NT

[harry]

LEDs are slightly better than electronic ballast fluorescent lights.

Some way better than switch start.

Plus instant start. Several colours available.

[whisky-dave]

This lab was build in the 1960s last electrical refurbishment was in the mid 90s. But still never seen any dimmable florescant in the dept or uni, there must be a reason. And the electric car existed in about 1880.

wasn't exactly a tesla or even a prima though.

[NY]

How are fluorescents dimmed? I'd always thought that it was impossible, and was surprised when the fluorescents in my school lecture theatre could be dimmed. They were probably installed in the early to mid 70s, which gives an idea of what technology was available then. I remember a huge cabinet about the size of a 6-foot high freezer in the projection unit which gave off a hell of a hum as the lights were going from full off to full on, which they did on a timer: the lecturer pressed a button and they dimmed/brightened automatically over the course of about 5 seconds.

[whisky-dave]

I waqsnt; sure so looked it up.

well I knew it was possible but a bit more difficult than just replacing a light switch with a dimmer switch.

I had a brief look at how the stage lighting in the school worked in the late 70s, just seemed to be large covered rheostats covered in dust. A selection of coloured filters were in a cardboard box too.

Yes most of us have evolved since those days, in most cases we have better kit and better ways of doing things now.

[NY]

I helped with the lighting in the school hall (an older building with a proper proscenium arch, wings and a curtain) and they used huge wire-wound rheostats which were operated with a length of wood to fade many up or down at the same time.

There was also a huge circular drum rheostat for dimming the house lights, and we were given strict instructions to make *certain* that the big circular handle was in the fully-anti-clockwise (min) position before turning on or off (to avoid turning them on/off suddenly) and when we started to fade them either way, do it *quickly*, taking no more than about

5 seconds to go from one end to the other (accompanied by a loud screeching of the contact on the wire!) to avoid running the rheostat at part-load for any longer than necessary. Even then, we could see the wire glowing in the dim light of the wings where the lighting board was.

The lecture theatre was equipped with lots of theatrical lights, and a nice "new" (at the time) triac dimmer system with tiny sliders for diming the lights, but it was never used for plays because there were no wings (other than exiting through the fire doors either side into the playground) and there was no curtain.

[Dave Plowman (News)]

With old fashioned ballasts, possibly. But high frequency ones have been around for many years now. The light output does go down slightly with age, though.

Many might prefer to have the colour temperature they want from the off without messing about.

Dimming florries with electronic ballasts has also been around for many a year. The ones lighting my kitchen worktops - installed some 20 years ago.

[Dave Plowman (News)]

Even earlier than that, Charles. Our school hall had them in the 50s. Although not something that would fit in a one gang box. ;-)

[Dave Plowman (News)]

Generally, florries in a lab are working lights. Why would you need to dim them?

[Dave Plowman (News)]

With the electronic ballasts I have here, all you need to add is a simple pot to dim them.

[Andrew Gabriel]

It is basically replacing the light switch with a dimmer (suitable for inductive loads), but you also need to add a separate pair of isolated supplies to keep the filaments hot enough to continue operating in thermionic emission mode when the tube current is too low to do it just by itself. This will also enable the tube to strike without a starter.

Indeed, I made just such a light as a teenager.

Commercially, Transtar was a well known manufacturer of dimming magnetic ballasts (and very high quality non-dimming ballasts).

One issue with banks of dimming fluorescents is all the tubes had to be replaced together, otherwise newer and older tubes are significantly different light output, and different makes can be different too.

Also, you get colour shift and a significant drop in CRI when dimming fluorescents, as the ratio of light output from the different mercury line changes, which upsets the colour balance from the arc and the phosphor (tend to lose more green and end up with purple from the over balance of red and blue).

Nowadays with microcontroller based electronic ballasts, adding dimming is trivial, although it's not done by using triac dimmers. 0-10V, DALI, switch-dim, or photocell to generate constant lux level are common, and many electronic ballasts support multiple of these.

Indeed, many electronic ballasts support multiple different tubes that run at different currents, and having identified the tube in use from the electrical characteristics, effectively use the internal dimmer logic to limit the current to the max allowed for the identified tube.

[charles]

I can quite believe that, but I first met them in 1961.

[Weatherlawyer]

This may sound like a silly question What?