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Mr. Tight Watt: Lighting questions  Smart Choices Archive

Mr. Tight Watt: Lighting questions

Check out these answers to lighting questions. Have a question? Ask Mr. Tight-Watt!

Ask Mr. Tight-Watt

Many of the questions that readers pose to Mr. Tight Watt focus on lighting. This month is no exception. Here are answers to Mr. TW’s most recent questions. Jim Sayers, energy services director, Corn Belt Power Cooperative, Humboldt, Iowa, answers the questions for Mr. Tight Watt.

Question 1: I have a Directional Reflective CFL (GE brand) that fell and the outer glass, NOT the spiral tube, broke. Is the mercury only contained within the spiral tube? Or did I expose myself and family to mercury? –John, a Smart Choices reader

Answer: The small amount of mercury in CFLs is inside the spiral tube as part of the gas that provides fluorescence. The purpose of the reflective outer glass is for appearance, lighting reflection, and protection. So in your case, it served its protective purpose for the spiral bulb inside. So you can safely dispose of the remaining bulb without concern for exposure to mercury.


Question 2: I just tried a 42-watt CFL (2700 lumens) bulb, and it looked dull and yellow. What bulb will replicate a bright 200-watt incandescent bulb? –Scott, a Smart Choices reader

Answer: A 42-watt CFL should have a light output about equivalent to an incandescent of about 170-200 watts, so you are OK on wattage. I believe you mean the bulb is 2700 k, a measure of the light’s color. The higher this number, the “cooler” the light output – more blue and not so yellow. So I would look for a bulb with a higher k value. We have found many of our members like bulbs in the 5000 k range.

For more information, check out these resources:
• A good general overview from energy.gov
• A chart that shows relative colors and color temperature comparisons
 

Question 3: I am wondering if you know anything about 0.8W bulbs? (They're supposedly Super Energy saving bulbs.) –J, a Smart Choices reader

Answer: No, I have not heard of that low of wattage bulb, unless it would be for decorative or accent lighting purposes. At .8 watts, even if it is an LED, it would not have very many lumens of output.

I did find one on Home Depot website. This is an LED rated at 1 watt – but lumen output is only 60 lumens – not very much light.

For reference I find this guide helpful – showing substitutions for typical sized bulbs.

Question 4: What CFL with a standard base can give me the bright white light of a 150-watt bulb? –Scott, a Smart Choices reader

Answer: There are several online charts to show equivalency to an incandescent 150-watt bulb.

For a rule of thumb, I usually figure a CFL uses 25 percent true energy of an incandescent for equivalent light (lumen) output. So a 150-watt incandescent produces about 2600 lumens. Dividing 2600 by 4 gives you a CFL bulb of 37.5 watts.

Also remember to check the bulb’s k (color) rating - 5000 k or higher provides a whiter (daylight) colored bulb.

Use these resources to help you choose the best option and find more about lighting:
• FTC
• Choosing a Bulb from Lumennow.org
 

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

 

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