A 3-way bulb gives three light levels in a lamp whose socket and switch are made for it. Match the old bulb’s base and levels, such as 50/100/150 on a standard base, or 100/200/300 on the large mogul base of some torchiere floor lamps.
How a 3-way bulb works
ENERGY STAR defines a 3-way bulb as one that gives separate light levels in a lamp socket controlled by a switching mechanism. GE lists its 3-way A19 on a DC medium base, short for double contact.
The three levels come from the lamp’s switch, not from dimming. GE’s and Feit’s 3-way LEDs are marked non-dimmable.
The numbers on the box
A 3-way bulb’s Lighting Facts label lists each level, such as 800/1600/2500 lumens. LED 3-ways are named for the old bulbs they replace, such as 50/100/150 watts.
| Bulb | Replaces (W) | Lumens |
|---|---|---|
| GE A19, DC medium base | 50/100/150 | 2155 on high |
| Feit A21, E26 (A50/150/927CA) | 50/100/150 | 800/1600/2200 |
| Feit A19, E26 (A30/100/927CA) | 30/70/100 | 500/1050/1600 |
All three are marked non-dimmable.
The LEDs themselves use 17 watts on high for GE’s, 7, 15 and 23 watts for Feit’s A21, and 5, 9 and 16 for its A19.
Under ENERGY STAR’s rules, which ended for bulbs on December 31, 2024, a 3-way bulb’s watt claim was rated on its highest setting. A 50-100-150 bulb had to give 2,150 to 3,000 lumens there, and a 30-70-100 bulb 1,200 to 1,999.
Mogul 3-way bulbs
Some torchiere-style floor lamps take a bigger 3-way bulb on a mogul (E39) base. Satco’s mogul 3-ways replace 100/200/300 watt bulbs, such as its S11490 at 1300/2900/4100 lumens. Check the old bulb’s base before you choose.
Turn the lamp off, unplug it, and let the bulb cool before you change it.
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