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Ask Mr. Tight-Watt: Bulb wattages  Smart Choices Archive

Ask Mr. Tight-Watt: Bulb wattages

Using CFL bulbs in your fixtures is a safer option, and also saves energy.

Ask Mr. Tight-Watt

Many of the questions our readers ask Mr. Tight-Watt relate to lighting issues. This month, a reader asks the following question:

Can I put 100-watt light bulbs in my overhead lights that have a 60-watt mark on them? –Jessi, a Smart Choices reader

Mr. Tight-Watt called on our lighting expert, Rob Kirkpatrick with Service Concepts, to answer Jessi’s question.

According to Rob:
“The answer to this is: No. Please don’t. The reason those fixtures are limited to 60W incandescent bulbs is because 90 percent of the electricity that powers an incandescent light bulb is converted to heat – only 10 percent goes to light. Design specs and UL approval for those fixtures is based on the maximum heat that a 60W incandescent light bulb will produce, and putting a 100W bulb in there is adding 67 percent more heat energy than the fixture is designed for. Exceeding those design specs could result in a fire hazard.

Part 2: If you were to ask ‘Can I put a 100W equivalent CFL in there’? the answer would be ‘If it fits, it’s OK.’ That would typically mean a 23 Watt CFL, so you’d have more light, even less heat, and all would be well in the world. Sometimes the space is pretty tight, and a 23W CFL may not fit the space. However, our manufacturers indicate that it is OK to put any of their CFLs up to 23 Watts in an enclosed fixture, if they will fit.

Here’s another rule of thumb: Don’t put an enclosed CFL in an enclosed fixture. You may have seen some CFLs where the spiral tube is enclosed inside of an outside glass shell which is shaped like a globe bulb or a flood light bulb or even a standard light bulb (we refer to that as an 'A-lamp'). Those CFLs, with an outer glass shell, should not be installed in an enclosed ceiling fixture. They are made for table lamps or bathroom light bars or ceiling cans, but not fixtures that are entirely closed up like your ceiling fixtures.”

Do you have a question for Mr. Tight-Watt about lighting, insulation, heating and cooling, energy audits, ENERGY STAR, or other energy-efficiency questions? If so, send him your questions.


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