Electrical – What lamps available in the UK are compatible with BS 546 plugs

I had the same issue when outfitting two homes with Insteon dimmers (which support both multi-location control and full home automation with an optional computer link) over the past 6 years. For CFL bulbs, it comes down to the design of the ballast. I used a combination of forum research and experimentation to find no-flicker bulbs, and have the following recommendations (in order of availability & price):

1. TCP SpringLamp series
2. Overdrive Lighting dimmable spiral
3. EarthTronics / EarthBulb
4. Dimmable CCFLs from LiteTronics or TCP (no high-lumen models)

All of them work wonderfully for me with a wide range of dimming and no flicker. One caveat: very low dim levels cause an audible whine on some of the bulbs, particularly the TCP models.

I've read about positive results with LED lamps as well, but the price isn't right (for me) yet.

There's probably no such thing as a F32T12, but I could be wrong.

You might check with a local electrical distributor / wholesaler. Where I work we still stock the F34T12CW-SS (super saver) and still buy them from our chosen lamp manufacturer.

The main reason is you would have to buy an electronic ballast instead of the old magnetic (core and coil) ballast. When you match an F34T12 with an electronic ballast with an F32T8 electronic ballast, the wimpy F32T8 wins on lumen output 2735 vs. 2235. Also less energy is used. Color is also better with T8's but still not as good as incandescent or LED's in warmer tone.

The big DIY box stores probably don't mess with them because they would rather have you buying more energy efficient lamps and ballast.

Also effective July 14, 2012 the US Government will make lamp manufacturers to discontinue T12 lamps so if you just have to have T12 lamps you better buy a couple of cases.

On July 14, 2012, recently enacted DOE regulations will take effect that will also eliminate the T12 lamps that the ballasts operate. The new DOE rules expand on efficiency rules established by the Energy Policy Act of 1992 by strengthening standards for covered lamps types while also covering 8-ft. T8 lamps, 4-ft. T5 lamps and more wattages of 4-ft. T8 and T12 lamps. The net result, with few exceptions, is a majority of 4-ft. linear and 2-ft. U-shaped T12 lamps, many 8-ft. T12 and T12HO, and some low-color-rendering 4-ft. T8 lamps will be eliminated. While no longer popular in new construction, an estimated 30 percent of fluorescent 4-ft. lamps sold every year are T12, according to NEMA market data.

Above info from here

Fluorescent Lamp Ballasts — two regulations: (1) a DOE energy conservation standard that becomes applicable to full wattage new ballasts in 2005–2006, and retrofit ballasts in 2010 (65FR 56740) and (2) legislative standards for energy saver ballasts (e.g., F34T12) that become effective 2009–2010 from the Energy Policy Act of 2005. Both these regulatory measures shift the market from T12 (medium CRI) to T8 (high CRI) fluorescent lamps.

General Service Incandescent Lamps — passed as part of EISA 2007, this standard will essentially phase out the most common, least efficient incandescent lamps by 2012–2014. It also establishes a minimum threshold efficacy of 45 lm/W starting in 2020, which is modeled as a shift to lamps that have a very high CRI and an efficacy of 45 lm/W. See Section 321 of EISA 2007.

Fluorescent Lamps — a DOE energy conservation standard that applies to fluorescent lamps manufactured after July 14, 2012, adopting an efficacy standard that shifts the fluorescent market to T8 lamps (74 FR 34080).

Incandescent Reflector Lamps — a DOE energy conservation standard that applies to lamps manufactured after July 14, 2012, adopting an efficacy that requires premium halogen technologies (74 FR 34080).

Metal Halide Lamp Fixtures — passed as part of EISA 2007, this standard sets minimum efficiency requirements on ballasts that operate metal halide lamp fixtures. See Section 324 of EISA 2007.

Above info from PDF here, just search for F34T12

According to one of my co-workers, this is all moot because of December 21, 2012... ;)