Guides
Bulb codes, light color and dimmers, and how to use extension cords, power strips and surge protectors.
All guides
What bulb goes in a bathroom heat lamp?The infrared bulb the heater's label names: 250 watt BR40 or R40 on Broan's bulb heaters. Can I use an LED bulb in an enclosed fixture?Which LEDs can go under a closed glass dome, and what the box says. Can I put LED bulbs on a dimmer switch?A dimmable LED and an LED-rated dimmer, and how to fix flicker and buzz. Why do my light bulbs keep burning out?Why bulbs fail early, in the makers' words: the fixture, heat, the dimmer, switching and shaking. Why does my LED bulb glow when it's off?Why an LED can glow faintly with the switch off, from Leviton's support pages, and what to check. What bulb does a wax warmer take?The watts on the warmer's label, Scentsy's 10 to 25 watt bulbs, and E12 warmer bulbs. What bulb does a candle warmer lamp take?The warming bulb a candle warmer lamp's maker lists, such as Candle Warmers Etc.'s 25 and 35 watt bulbs. What bulb does a salt lamp take?The two bases Feit's salt lamp bulbs come on, and the lamp's own wattage limit. What 3-way bulb does my lamp take?Three levels from a 3-way lamp socket, what 50/100/150 means, and mogul 3-ways for torchieres. What do A19 and E26 mean on a light bulb?A19 is the glass shape and size; E26 is the screw base. A chart and a PDF. 2700K, 3000K, 4000K or 5000K: which light color?What 2700K, 3000K, 4000K and 5000K look like, and the names on the box. How long do LED bulbs last?What the hours and years on an LED's box mean, and how long they last if the light stays on. How do I clean up a broken CFL bulb?The EPA's steps for cleaning up a broken CFL or fluorescent tube, in its own words. How do I dispose of old light bulbs?Where CFLs, fluorescent tubes, LEDs and old bulbs go when they're done, and why local rules decide. GU10 bulbs: the push-and-twist baseThe push-and-twist spotlight base on household 120 volts, the bulb shapes it comes on, and how it differs from 12 volt MR16s. MR16 bulbs: 12 volt GU5.3 or 120 volt GU10The small reflector spotlight on a 12 volt GU5.3 base with a transformer, or a 120 volt GU10, and which LEDs work on the transformer. G9 bulbs: two looped pins, LED or halogenThe small capsule bulb with two looped pins, on 120 volts, as halogen or LED: lengths, dimming and the fixture's watts. GU24 bulbs: the twist-lock pin baseThe twist-lock pin base on ordinary bulb shapes such as the A19, in LED and CFL, and why it doesn't swap with E26. E12 bulbs: the candelabra baseThe small candelabra screw base: the candle, globe, fan and night light bulbs it comes on, and E12 vs E11, E14 and E17. E17 bulbs: the intermediate baseThe intermediate screw base between E12 and E26: microwave, refrigerator, sign and some ceiling fan bulbs. E26 vs E27: what's the difference?The US and European medium screw bases: close in size, used on different voltages, so match the one made for your country. A19 vs A21: what's the difference?The standard bulb in four sizes: how wide A15, A19, A21 and A23 are, how long, and whether the bigger one fits. A15 bulbs: the small standard shapeThe standard bulb shape at 1-7/8 inches across, on E26, E12 or E17, for ceiling fans and appliances. BR30 vs PAR30: what's the difference?Two 3-3/4 inch reflector bulbs with different beams, plus R30 and short or long neck PAR30s. PAR38 bulbs: size, base and outdoor ratingsThe 4-3/4 inch reflector flood on the E26 base: lengths, wet or damp ratings bulb by bulb, dusk-to-dawn PAR38s and dimming. ST19 and other Edison bulb shapesThe ST19 and the other filament shapes (ST15, ST20, T10, G25): widths, lengths, bases and what to check on the box. What bulb does a chandelier take?Candle bulb shapes for chandeliers and sconces (B10, B11, BA10, CA10, CA11), their tips and sizes, on E12 or E26. E39 mogul base bulbsThe large mogul screw base: 3-way torchiere lamps, corn-cob LEDs for garages and yards, and what to leave to an electrician. T8 vs T12: what's the difference?How wide T8 and T12 tubes are, the watts and light of some 4 ft. tubes, and what an LED tube needs to fit either. Which LED tube fits my fluorescent fixture?Which LED tube fits a fluorescent fixture: Type A on the ballast, Type B wired by an electrician, or Type AB. How to measure a light bulbMeasure the glass across its widest part in eighths of an inch to get the shape code's number, with a chart. S14 bulbs: patio string light replacementsThe size and base of the S14 bulbs in patio string lights, LED or incandescent, and what to check on the string. How many watts can an extension cord handle?Where a cord's watt rating is printed, and the amps and watts Southwire rates its cords for by gauge and length. Can you use an indoor extension cord outside?Why only a cord marked for outdoor use goes outside, how to tell one, and how to keep it safe out there. Can you plug a space heater into an extension cord?Why a space heater goes straight into a wall outlet, never an extension cord or power strip, and what to do when there's no outlet nearby. Can you plug a refrigerator into an extension cord?Why GE, Whirlpool and Frigidaire say a fridge or freezer goes straight into its own grounded outlet, with no extension cord. Can you plug a window air conditioner into an extension cord?Why GE, Midea and LG say a window air conditioner goes straight into a wall outlet, and the one cord rating LG's manual gives. What extension cord do you need for a generator?Heavy-duty outdoor cords from the generator to your appliances, carbon monoxide, and why it never plugs into a wall outlet. What extension cord do you need for a power tool?The cord table in your tool's manual, where Milwaukee's differs from DeWalt's, Makita's and Bosch's, and air compressors. Can you use an extension cord with an electric pressure washer?Worx and Ryobi don't recommend an extension cord. The gauge and length their manuals allow, and keeping the connection dry. How many joules does a surge protector need?What the joule rating means, Tripp Lite's suggested 1,000 joules, and why Eaton and Schneider caution against comparing by joules. Can you plug a power strip into an extension cord?Plugging power strips and extension cords into each other (daisy chaining), what UL says, and what to do instead. Why does my extension cord trip the GFCI?What to check when a cord, outdoor lights or a pressure washer trips the GFCI, and when to call an electrician. Why is my extension cord hot?What a hot or melted extension cord means, what to check, and when to call an electrician.