<P> A standard screw lamp socket has only two electrical contacts . In the center of the bottom of a standard socket is the hot contact (contact one in photo), which typically looks like a small metal tongue bent over . The threaded metal shell is itself the neutral contact (contact three in photo). When a standard bulb is screwed into a standard socket, a matching contact on the bottom of the bulb presses against the metal tongue in the center of the socket, creating the live connection . The metal threads of the bulb base touch the socket shell, which creates the neutral connection, and this is how the electrical circuit is completed . </P> <P> A 3 - way socket has three electrical contacts . In addition to the two contacts of the standard socket, a third contact is added . This contact is positioned off - center in the bottom of the socket (contact two in photo). This extra contact matches a ring - shaped contact on the bottom of a 3 - way bulb, which creates the connection for the second filament inside the bulb . A problem of these devices is that the ring contact of the socket (contact two in photo) digs into the lead seal on the lamp bulb's contact ring and this connection tends to fail early (sometimes in months), leading to intermittent flashes, popping noises, and loss of power to the low wattage filament as the lead seal on the bulb's ring alternately melts and solidifies . </P> <P> The center contact of the bulb typically connects to the medium - power filament, and the ring connects to the low - power filament . Thus, if a 3 - way bulb is screwed into a standard light socket that has only a center contact, only the medium - power filament operates . In the case of the 50 W / 100 W / 150 W bulb, putting this bulb in a regular lamp socket will result in it behaving like a normal 100W bulb . </P> <P> A 3 - way socket that is to be wired to a separate 3 - way 2 - circuit switch, is called a "keyless 3 - way socket ." This would be typical in a 3 - way floor - standing torchiere lamp . A "keyed 3 - way socket" has the switch incorporated in the lamp socket and requires no external wiring between switch and socket . </P>

Do 3 way light bulbs work in any lamp