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I consult to most all warm air furnace OEMs. The best answer is it lights the first time, every time. There are of course things that can prevent that...low gas pressure switches, low air pressure switches, limits not being made (door switch, air switch, fan speed proving, condensate switches, etc.). That being said...EVERYTHING good...GAS supply...AIR ...


@jms was right. The ribbed wire was mixed with the smooth wire at the bulb end. I switched them but it still didn't work. The voltage when on was about 0.7V. I tested with a straight connection like @DigitalNinja said and it did light up! So the brand new switch is bad!


I gather this is an expensive, quality fixture that uses dual T5 bulbs, and it has an electronic rapid start or progammed start ballast (that is to say, there's a small time delay before it comes on). All fluorescents are discharge lights (like neon, mercury vapor, sodium and metal halide). They all work by putting high voltage between the ends of the ...


Difficulty starting is a symptom of worn-out fluorescent tubes. They have a finite lifetime. Some might die after a couple of years regular use, some from the same batch might last ten or more years. See if the tube is slightly darker near one end. Either Change the starter (only on older fittings), or Change the tube Or Replace the fitting with a LED ...

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