Anablog

Actually two ballasts failed. These are from Advance Transformer Company and I really don’t think it is their fault. Heck it might be my fault since I see that there are different colored wires that are supposed to hook to the 40-watt circular and the 32-watt circular light. The ballasts were mounted in a flush-mount ceiling fixture that has absolutely no provision for air circulation.

I taped a thermocouple to the side of the ballast and my trusty Fluke 52 dual J/K thermocouple meter said the temperature got to 93 degrees centigrade. Worse yet, my trusty Fluke 80T-IR infrared meter would read a good 10 degrees hotter when I pointed it at the paper label, something that should have an emissivity of about 1.0. I can only imagine what the temperature of the windings were, certainly too hot for my liking. I don’t want anything in my house wiring that is over 100°C. Finding the replacement ballasts was pretty straightforward. Some places wanted 66 bucks each. I found the RS-32-40-TP-W ballast on an outfit called Drillspot. Funny thing though is that they just got the ballasts from good old Grainger, who has a large store right here in Sunnyvale. I guess it was for the best since the one ballast came from the San Jose location and another was from out-of-state. Price was 33 bucks each plus shipping.

I installed the new ballasts but who wants to watch them burn out again due to a bad fixture design? So I drilled a bunch of holes in the side of the fixture and cut a huge hole in the plastic cover to let the air flow up and out. Sad thing is that it did not make much difference. Where the ballast would get to about 67°C with no cover on the fixture, it still got up to 83°C with the cover that had the holes in it.

Better than 93°C, but still a little too hot. I have two fixtures like this so I will take a saw to the other fixture and open some huge holes in the side and see how that works out. One benefit of cutting the big holes in the frosted plastic cover right below the ballast is that it lets me shoot the temperature with the Fluke 80T-IR any time I feel like it. I knew these ballasts were failing since in the summer they would stop working if I had the lamp on for a few hours.

That is just about the time constant for the ballast temperature. Then the ballast would cool off and the two circular lamps would come on again. Then off… then on….until one of the fixtures stopped working altogether. Popping out the cover showed the melting potting compound and it was a safe bet that I needed new ballasts.

This is the sad fact of fluorescent lamp costs. I don’t care if they use no electricity, if I have to order new ballasts and replace them every five years it would be cheaper to use incandescent bulbs. Now I finally get the promise of LED lighting, yes even general lighting for the home. If they are replacing incandescent lights, the LEDs are way more expensive. But if they replace the fluorescent, they use as little or less electricity and since the ballast is not a big air-gap transformer but a switching power supply, let us hope the LED lamp ballast will not fail every five years. I see why Cree took me to task for the negative blog I did about LED lighting a year ago. At the time LED fixtures were still less efficient and very costly, but costs have plunged and efficiency is even better. Right now Cree has LEDs that beat the efficiency of compact fluorescents (Yes, wall outlet to lumens) and soon I expect they will get to the efficiency of the T-8 4-foot bulbs with electronic ballasts. Sure the LED fixture still costs a ton more, but if you don’t have to climb up a 30-foot ladder to replace the ballast (or the bulb for that matter) there is almost no cost too high to not make the LED lamp look good.

Oh, and I did not mention that, yes, there is still another fluorescent light problem I have, in the recessed-can fixtures over my porch. I can’t find the right bulbs. Furthermore these cans are on an IR motion sensor and that is always bad for fluorescent bulbs. It was over a year ago I had an exchange with Geoff Ling at Gallium Lighting.

The Gallium Lighting LED fixture, I want them.

He and president Keith P. Bahde explained that my old blog was right— for a year before that. They said that since then, there had been huge improvements in LED efficiency and that is how I learned that Cree and Osram had LEDs that beat compact fluorescent (CFL) efficiency and those T-8 and T-12 lamps may be next to fall. They also provided independent testing to show that they could beat CFL efficiency and it was a fair test, wall-socket to lumens. I was surprised to learn that a CFL fixture loses a lot just because they have to bounce the backside light forward, even a chrome reflector causes losses, if only because some of that light gets blocked by the bulb itself. Geoff explained to me that the starting mechanism in a CFL is what limits the number of cycles that you can turn it on. This means that you should not put them on a motion sensor like mine are. I am going to order a set of recessed-can fixtures from Gallium’s distributor (no, I will pay for them, EDN has a strict ethics policy about getting valuable gifts from anybody). The older objection to CFLs, that you can’t put them on a dimmer, has already been addressed by Infineon, International Rectifier and others. They have ballast chips that take an SCR dimmed ac power and translate it to a PWM dimmed power source for the CFL. Pretty neat stuff, so from now on it is only electronic ballasts for me, whether fluorescent or LED, I am tired of melted plastic dripping from my fixtures.

All I will say is that the florescent light manufactures have better get their act together if they want to stay competitive. They have a price advantage right now but they have to take the stupid old iron transformers out of the ballasts and use semiconductors to make long-life electronic ballasts like my beautiful GE UltraMax that I mentioned in my previous blog. As long as those old iron ballasts are failing in 5 years, there is absolutely no cost benefit to fluorescent.

I know Jim Williams over at Linear Technology has designed many great cold-cathode florescent lamp drivers for laptops, but LT does not make chips for off-line ballasts. I know Fairchild and International Rectifier do, so maybe Jim and I will whip up an electronic ballast for the dual circular fluorescent lights in my kitchen. I am sure we can get the ballasts to run cooler than 107 degrees centigrade.