Is your lamp cord coming loose at the plug? Here's how to replace a polarized plug safely and easily.
ComplexityBeginner
Introduction
A damaged lamp cord is more than just an inconvenience, they're a hazard to yourself and your home. But you don't have to toss a lamp because the plug is damaged. For many DIY enthusiasts, myself included, replacing a damaged electrical cord or plug is a first step into working with electrical.
Plugs are a common failure point for corded electrical devices. They often get damaged when the user unplugs them by pulling on the cable, rather than gripping the plug casing itself. Instances like this, where the majority of the cord is intact, can typically be fixed by replacing the plug. It's a simple fix, but it can save you from having to send expensive electronics to the landfill.
Safety First
I asked Ben Kolo, a veteran electrical contractor and owner of Mr. Electric of Central Iowa, what safety precautions are essential for homeowners fixing a lamp cord.
"Always unplug the lamp before working on the cord," he suggests. This includes examining the cord for damage. If you run your hands over a damage cord while it's plugged in, chances are you'll be in for a shock.
Secondly, he says to "make sure you have the proper tools such as wire cutters, wire strippers, electrical tape, and screwdrivers." The right tool for the job makes electrical work easier and safer.
Because the cord will be unplugged while you work on it, this is a great project for beginners. Of course, working with electricity means you'll have to use caution and follow proper wiring protocol. It's not difficult, but it does require attention to detail and the patience to make sure you get it done right.
Buy the Right Replacement Plug
Examine the plug to be replaced. Does it have two prongs or three? If two, are the prongs polarized (meaning that one is larger than the other) or non-polarized? The new plug will be a like-for-like replacement.
Lamp cords and two-wire extension cords are almost always polarized.
Never use a non-polarized replacement plug to replace a polarized plug. (Non-polarized plugs are often found on double-insulated tools and some appliances.)
A polarized plug has a small blade for the hot wire and a wide blade for the neutral wire. It's essential that the wires feeding those blades not be reversed when you replace the plug in order to prevent shocks.
Polarized plugs are easy to find online and at home hardware centers.
Tools Required
- Screwdriver
- Wire stripper/cutter
Materials Required
- New plug
Project step-by-step (5)
Step 1
Identify the Neutral Wire
Since connecting the neutral and hot wires to the right side of the plug is essential, the first step is to identify which wire is which. You can identify the neutral side of an electrical wire by looking for markings. The most common identifier is ribbing in the rubber insulation all along one edge, but it can also be a white wire or a white stripe.
- Ensure that the cord is unplugged from the outlet.
- Examine the cord, looking for markings that indicate which wire is hot and which is neutral.
- The most common ways to indicate this are in the photo below, but your specific wire may use a different marking system.
- You can often identify the neutral wire before removing the old plug, but that’s not always true. You may need to remove the old plug first and then identify the neutral wire.
- While you’re examining the cord, Kolo suggests checking for any additional damage on the rest of the cord.
- Look for fraying, cuts, or burn marks.
- If damage extends further down the cord, replacing the entire cord rather than just the plug is safer.
Step 2
Remove the Old Plug
It’s time to remove the damaged plug, along with any section of damaged cord.
- Ensure that the cord is unplugged from the outlet.
- Use wire cutters to clip the cord past the damaged section.
Step 3
Strip the Wires
Now, we have a flat end of the power cord, and we need to expose the bare copper wires. We’ll do this by pulling the wire through the wire stripper.
- To prepare the cut end for a new plug, cut or pull the two sides apart, then strip off about 3/4 in. of insulation.
- Typically, lamp cords are 18 gauge, but if you’re not sure, strip the wire through the 14- or 16-gauge slot first. If it doesn’t strip cleanly, try the next gauge. (Remember that lower-gauge wires are larger in diameter than higher-gauge wire.)
- Note: Stranded (“STRD”) wire gauges are marked on the left, solid gauges are marked on the right.
Step 4
Wire the New Plug
Now, all we have to do is connect the wires and seal the plug.
- Wrap each wire around the correct screw, with the neutral on the wide-blade side. Tighten the screw to secure the wire in place.
- Always wrap the wires in a clockwise direction around the screw.
- Wrapping it clockwise ensures that when the screw is tightened, the wire will be pulled in even more securely.
- Always wrap the wires in a clockwise direction around the screw.
- “Make sure all connections are tight,” says Kolo, “as loose connections can lead to shorts or electrical fires.”
- Snap or screw the plug back together.
Step 5
About the Expert
Ben Kolo opened Mr. Electric of Central Iowa after being an electrician for many years. His vision for a successful company is to hire the best in the industry, create a noble culture, and simulate this to his clients.
