A damaged lamp cord can be repaired by replacing the plug or the cord set while keeping polarity correct and using UL-listed parts.
Small household lamps fail more from tired cords than from anything inside the socket. If the insulation is nicked, the plug is loose, or the inline switch crackles, don’t keep using it. Below you’ll find clear steps for how to repair a lamp cord, what to buy, and how to check your work so the lamp runs safely for years.
Quick Choices: Repair Paths And When To Use Each
Pick the fix that matches what you see. If more than one item looks worn, do the larger replacement.
| Problem | Best Fix | Notes |
|---|---|---|
| Cracked or frayed cord jacket | Replace full cord set (plug + cord) | Fastest, safest; match SPT type and wire gauge |
| Bent or loose plug blades | Install new polarized plug | Wide blade = neutral; keep polarity |
| Inline switch failure (sparks, no click) | Replace inline switch | Match amperage/voltage; preserve polarity |
| Socket shell gets hot or flickers | Rewire socket leads | Screw shell must land on neutral |
| Nick near the base exit | Shorten and re-terminate inside base | Add strain relief so jacket can’t pull |
| Non-polarized old plug | Upgrade to polarized plug | Safer orientation; matches modern outlets |
| Stiff or brittle jacket (age/heat) | Replace full cord set | Choose SPT-2 for thicker insulation |
| Loose cord at base entry | Add or replace strain relief | Stops tugging forces from reaching terminals |
Safety First And What The Codes Say
Unplug the lamp before any work. If the jacket is split or copper shows, stop using it until repaired. The U.S. Consumer Product Safety Commission advises replacing damaged cords rather than taping over them, since exposed conductors can lead to shock or fire. You can see that guidance in the CPSC’s home electrical checklist (CPSC electrical checklist PDF).
Polarity matters. The grounded (neutral) conductor must land on the lamp’s screw shell, and the wide blade on a polarized plug is neutral. This orientation reduces the chance of touching a live shell during bulb changes. OSHA’s rule for lampholders spells that out in plain terms: where a grounded conductor exists, it goes to the screw shell (OSHA 1910.305(j)(1)(iv)).
Know Your Cord: SPT Types, Gauge, And Polarity Marks
SPT-1 Vs. SPT-2
Most table lamps use flat “zip” cord labeled SPT-1 or SPT-2 in 18 AWG. The copper size is often the same; the difference is insulation thickness. SPT-1 jackets are about 0.03 in. thick and bend easily. SPT-2 jackets are roughly 0.045 in. thick and add abrasion resistance. Pick SPT-2 when you want a tougher outer jacket; pick SPT-1 for easy routing where the cord won’t be abused. Trade sources explain that insulation thickness changes durability, not the current rating for a given gauge (SPT-1 vs. SPT-2 overview).
Polarity Clues On The Jacket
On flat lamp cord, one side has ribs or a stripe. That ribbed side is neutral. The smooth side is hot. On clear cord, the silver-colored conductor is neutral and the copper-colored conductor is hot. Keep those landmarks straight through the entire repair so the wide plug blade and the socket shell both tie to neutral.
Tools, Parts, And Prep
- Replacement polarized plug or full replacement cord set (UL-listed)
- Inline switch (if you’re changing a failed switch)
- Wire cutter/stripper sized for 18 AWG
- Small flat screwdriver and Phillips screwdriver
- Needle-nose pliers
- Strain relief bushing or metal clamp (if missing or damaged)
- Tape for temporary labeling (mark neutral while you work)
Lay a towel on the bench so parts don’t scratch. Take a quick photo of the original routing inside the base so you can copy it during reassembly.
How To Repair A Lamp Cord: Replace A Damaged Plug
1) Remove The Old Plug
Some plugs are molded and can’t be opened. In that case, cut the plug off square, leaving enough length to work with. If the plug is a screw-together style, back out the center screw and open the housing.
2) Prepare The Cord
Separate the two conductors about 1 inch. Strip about 3/8 inch of insulation from each. Don’t nick the copper. If you do, cut back and strip again.
3) Identify Neutral And Hot
Find the ribbed side: that’s neutral. The smooth side is hot. On a polarized replacement plug, the terminal feeding the wide blade is neutral, and it’s often silver-colored. The hot terminal is often brass-colored. Many plug instruction sheets show this mapping clearly (see a typical Leviton sheet: Leviton plug instructions).
4) Clamp And Terminate
Slide the cord through the plug body and strain relief path first. Wrap each copper end clockwise around its screw so tightening the screw pulls the wire under the head. Neutral to silver (wide blade), hot to brass (narrow blade). Tighten firmly, but don’t crush strands.
5) Close The Plug And Test Fit
Reassemble the housing. Tug gently on the cord; the strain relief should take the load, not the terminals. Plug into a receptacle and run a quick test with a known-good bulb. If the lamp has a metal socket shell, check that the shell ties to neutral by visual tracing: ribbed side → silver screw at socket → shell.
How To Replace The Full Cord Set
1) Open The Base
Unthread the socket shell. Many shells have a small “press” spot; press and pull straight up. Inside you’ll see two screws: silver (neutral) and brass (hot). The center bottom of the socket has the hot contact; the outer shell is neutral.
2) Free The Old Cord
Loosen both screws and remove the conductors. If there’s a knot or a clamp inside the base, release it. Feed out the old cord and inspect the path to be sure edges won’t nick the new jacket.
3) Install Strain Relief
Snap a bushing into the base hole, or tighten a two-screw clamp where the jacket enters. This step matters for longevity; it keeps tugs from reaching the terminations.
4) Route And Terminate The New Cord
Thread the new cord up through the base and through the lamp body to the socket. Tie an Underwriter’s knot if your socket lacks a built-in clamp. Land the ribbed (neutral) conductor on the silver screw that bonds to the shell. Land the smooth (hot) conductor on the brass screw that feeds the center tab.
5) Reassemble And Test
Reinsert the socket shell and align any keyways. Gently tug on the cord at the base to confirm the strain relief holds. Install a bulb and switch on.
Replace Or Add An Inline Switch
An inline rocker or thumbwheel can fail long before the cord does. If you need a new switch, pick one rated for 125 V, 3–6 A or higher. Cut only the hot side (smooth jacket). Leave the ribbed neutral unbroken.
Inline Switch Steps
- Mark the hot side with a bit of tape so you can track it after you separate the conductors.
- Split the jacket about 1.5 in. where the switch will sit.
- Cut the hot conductor only. Strip 3/8 in. on both cut ends.
- Feed the cord into the switch body per the arrows, then clamp each hot end under its terminal.
- Close the case, making sure the neutral passes straight through in the other channel.
Taking Care With Polarity And Plugs
Modern two-prong plugs are often polarized. The wide blade and the wide slot in the receptacle tie to neutral. UL and product standards require that a polarized plug be installed and labeled to maintain that orientation during replacement, which is why replacement cord sets ship with warnings to keep the wide blade on neutral (UL 817 marking examples).
Lamp Cord Repair Keyword Variant: Taking A Lamp Cord Repair The Right Way
This section keeps the same theme and helps you apply it to any small table lamp. The steps don’t change: inspect, pick the correct fix, keep the neutral on the shell, and finish with a firm strain relief. By repeating the polarity checks at the plug and at the socket, you avoid the most common wiring slip.
Troubleshooting After The Fix
If the lamp still acts up after a neat repair, retrace the basics first: bulb, socket spring tension, and your terminations. Many “bad cords” turn out to be weak socket springs that barely touch the bulb tip. With the lamp unplugged, bend the center tab in the socket up a hair so it makes solid contact.
| Symptom | Likely Cause | Fix |
|---|---|---|
| Flicker when wiggled | Loose terminal screw or weak socket tab | Retighten screws; lift tab slightly |
| No power at all | Blown bulb, bad switch, open hot lead | Swap bulb; meter the switch; re-terminate hot |
| Plug feels warm | Loose blade contact or poor clamp | Replace plug; ensure strain relief engages |
| Hum or buzz | Loose parts vibrating at 60 Hz | Snug socket, harp, and finial; add felt pad |
| Trips breaker | Shorted conductor or pinched jacket | Inspect path; replace full cord set |
| Shock when touching shell | Polarity reversed | Move ribbed neutral to shell; correct plug wiring |
| Switch sparks | Worn contacts | Replace inline switch |
Strain Relief, Knots, And Routing
A good repair survives tugs. Use a snap-in bushing at the base exit or a clamp inside the base. If your socket lacks a clamp, tie an Underwriter’s knot right below the socket so tension never reaches the screws. Keep bends broad, and avoid sharp metal edges. If needed, add a rubber grommet inside the base hole.
Testing With A Multimeter
A minute with a meter proves the wiring is sound:
- Set to continuity. Touch one probe to the wide plug blade and the other to the shell. You should hear a beep.
- Touch the narrow blade and the socket center tab. You should hear a beep.
- No continuity should exist between the blades themselves with the switch off.
If any reading disagrees, trace the ribbed side and move it to the shell side. Don’t guess—follow the markings and fix the mapping before you power up.
Inline Notes On Parts Quality
Choose UL-listed plugs, switches, cords, and sockets. Keep the amp rating at 10 A or more for 18 AWG. Match color and finish to the lamp style if you care about looks. When in doubt about jacket toughness, pick SPT-2. Avoid old stock non-polarized plugs when upgrading a lamp; a polarized plug is the safer pick for modern outlets.
Care Tips So You Don’t Repair Again Soon
- Don’t run the cord under rugs or through door gaps where it can be pinched.
- Pull the plug body to unplug; don’t yank the cord.
- Keep cords away from heater vents and hot bulbs.
- Dust the socket and switch now and then; grit shortens their life.
When To Replace The Lamp Instead
If the body is cracked metal with sharp edges, the socket is corroded beyond cleaning, or you see heat damage, a new lamp may be the smarter move. The cost of a cord, socket, switch, plug, and the time to tear it down can exceed the price of a safe new lamp.
FAQ-Free Wrap-Up: Your Safe Repair Checklist
Polarity Checklist
- Ribbed jacket → silver screw at socket → shell
- Smooth jacket → brass screw at socket → center tab
- Wide plug blade → neutral (ribbed)
- Narrow blade → hot (smooth)
Quality Checklist
- UL-listed parts, correct gauge
- Firm strain relief at base and plug
- No nicks in the new jacket along the route
- Continuity readings match the map above
How To Repair A Lamp Cord: Final Notes
With a few low-cost parts and steady steps, you can bring a favorite lamp back to life. Keep the neutral on the shell, clamp the jacket so it can’t creep, and use rated parts from a trusted brand. When you follow those basics, the fix is tidy, safe, and durable.