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Mr. Tight Watt: More lighting questions  Smart Choices Archive

Mr. Tight Watt: More lighting questions

Steve Thrash, Service Concepts, answers readers' questions about lighting.

Ask Mr. Tight-Watt

One of the most changing industries in the energy-efficiency arena is lighting. That is one reason why our readers ask Mr. Tight Watt a lot of questions about lighting.

In this Q&A, our expert is Steve Thrash from Service Concepts, a partner with your electric cooperative. Check out lights available at a discount from Service Concepts.

 Question 1: Mr. Tight-Watt, I am using13-watt CFL bug lights in my outdoor light fixtures. The package said “not for use in light dimmers, light controls, and photocells.” However, the photocell I’d like to use states specifically, “dusk to dawn CFL light control.” It’s made by Utilitech. My question is: Is it OK for me to use this combination of CFL and photocell? What might be some consequences of incompatibility? –Jeff, a Smart Choices reader

Answer: CFL technology is temperamental and reacts to the slightest change in voltage, unlike incandescent lightbulbs. Manufacturers err on the side of caution and include the language that you reference.

Using CFLs with devices like dimmers, light controls, and photocells void the warranty. The reason? Electronic timers, photocells, or lighted switches may have “leak-through” voltage (also called “pass-through” voltage) even when the switch is off. Sensitive CFLs can read this low voltage coming through the line. The circuit board on a CFL then tries to start, but there’s not enough power for a start-up. Instead, the systems begins to cycle, and sometimes you can see the bulbs strobing. This cycling eventually burns out the circuit board components, causing early bulb failure. This is why CFL manufacturers put a disclaimer on their package.

If you have a device that meets the following UL (Underwriter Laboratories) standard (language below), then you can use a CFL with it. Your best bet is to follow the package instructions, or you may find that your lamps have less than optimal operating quality and shortened life.

(UL20 Sec. 7.6.15) Switches that are marked OFF shall completely disconnect all ungrounded conductors in the circuit when in the OFF (open) position. Switches that do not disconnect all ungrounded conductors, including switches that incorporate in-line components, such as neon indicators, that pass current through the load when the switch is in the open position, shall not be marked OFF.

Question 2: Can I use more than one dimmer switch in a CFL light circuit to control groups of lights separately? –Les, a Smart Choices reader

Answer: This question is somewhat related to the one above. We recommend using only one dimmer per circuit line because of pass-through voltage, always a risk in causing failed operations and/or shortened bulb life. One alternative is to use a lamp specifically designed for use with dimmer controls. For example, TCP Connect bulbs have a built-in dimming feature, which allows each bulb to be operated and dimmed individually using a smart device.
Question 3: How long should it take to install eighteen 75-watt fluorescent lamps in existing light fixtures? –Matt, a Smart Choices reader

Answer: Truly, it takes no longer than you’ve spent in the past installing incandescent bulbs. The only difference is the manufacturers’ recommendation to screw in the fluorescent lamps by holding the base, not the glass. That is because if you put pressure on the glass as you turn and twist it into the socket, you could cause hairline cracks that aren’t readily observed during installation. This will shorten the life of the lamp. NOTE: Beware of advertisements and commercials showing the installation of a CFL bulb, as many show installers twisting the glass top. This is not what manufacturers recommend as the proper way to install a CFL.

For more information
Read more answers to questions to Mr. Tight Watt, or to ask a question.


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