Guide 04 · Cords & plugs
Polarity is the difference between a lamp that's safe to touch and one that keeps its socket shell energized. On a polarized two-wire cord, the cord itself tells you which side is which.
The polarity map
Neutral — the ribbed or marked conductor. Goes to the silver screw, the wide blade, and the threaded shell of the socket.
Hot — the smooth conductor. Goes to the brass screw, the narrow blade, and the center contact.
Wide blade is neutral. Narrow blade is hot. That never changes.
Step by step
- Unplug and inspect. Replace the whole cord if it's frayed, cracked, or heat-damaged. Never work on a plugged-in lamp.
- Find the neutral side. Feel for ribs, printing, a tracer thread, or silver-colored strands. That conductor is neutral.
- Match the terminals. Ribbed to the silver screw and wide blade. Smooth to brass and narrow. Loop the wire clockwise under each screw.
- Secure and verify. Tighten firmly with no stray strands. Clamp the cord jacket, then close it up. Use a plug rated for the cord.
Safety
This applies to polarized two-wire lamp cords in the U.S. and Canada only. Never convert a three-prong plug. If the cord markings are unclear or the lamp has other damage, stop and consult a qualified electrician.