Light Bulbs and Lamps: LED, Halogen and Specialty

Base and shape come before wattage

A bulb has to fit the socket before anything else matters. Screw bases such as E26 (the standard North American size) and the smaller E12 are not interchangeable, and pin bases such as G4, GU5.3 and GY9.5 take specific lamps. Shape codes like A19, PAR30 and MR16 describe the glass and beam. Low-voltage lamps run on 12 V or 24 V through a transformer, while others run directly on 120 V, and a mismatch can destroy the lamp. Browse LED bulbs and strip lights for modern replacements, or general-purpose and specialty bulbs for halogen, fluorescent and discharge types.

Reading lumens, kelvin and technology

Brightness is measured in lumens, not watts: roughly 800 lumens replaces an old 60 W incandescent bulb, and the 'equivalent wattage' on a box says the same thing loosely. Color temperature in kelvin sets the mood, with 2700K to 3000K warm for living rooms, 3500K to 4000K neutral for kitchens, and 5000K and above daylight for task areas. Specialty lamps in this aisle quote far larger outputs, from thousands to over a hundred thousand lumens, plus lifespans that run from under a hundred hours for some projector and studio lamps to tens of thousands for LEDs.

Questions about Light Bulbs and Lamps: LED, Halogen and Specialty

Is a higher-wattage bulb always brighter?

Not with LEDs. Watts measure power use, and an LED makes far more light per watt, so a 9 W LED can match an old 60 W bulb. Compare lumens instead, and make sure the new bulb's wattage does not exceed the fixture's rating.

What do codes like A19, E26 and MR16 mean?

The first letters name the shape or base: A is the classic bulb shape, PAR a reflector and MR a small multifaceted reflector. In shape codes the number is the diameter in eighths of an inch, so A19 is about 2.4 inches. E26 is an Edison screw base 26 millimeters across.

Can I use a 120 V bulb on a 12 V circuit?

No. A bulb must match the supply voltage. A 12 V lamp on 120 V burns out at once, and a 120 V lamp on 12 V barely glows. Check the voltage printed on the bulb and on the transformer or fixture.