How To Replace a Plug on a Damaged Power Cord
Occasionally the plug on a lamp cord or some other device will become damaged. It is fairly easy to replace and should only take a few minutes. When replacing a plug, be sure to select a replacement that is the same as the one being replaced and with the same rating. Do not replace an ungrounded plug with a grounded plug, nor should you replace a ground plug with an ungrounded one. If the power cord itself is damaged, the damaged section should be cut off or the entire cord should be replaced.
Caution: Please read our safety information before attempting any installation or repair.
Electrical work requires safe practices. Always unplug the device before beginning work. Always use insulated tools for added safety. Some devices, including TVs and microwave ovens, can store a charge of electricity even when unplugged. Discharge these devices before beginning work.
Unplug the device.
If the plug is still attached, cut it off leaving only an inch or
so on the old plug. Also, cut off any damaged section of the power
cord. If the power cord does not have color coding or other markings
to identify each wire, make a mark on the power cord and on the small
tail left on the plug so that you can identify which wires were joined.
Take the end of the power cord and separate the wires so that each
is about one and a half inches long.
Inspect the old plug, if it has two prongs and they are identical
in size, then you may connect either wire to the connectors in the
If the old plug has different size prongs (aka blades) or a grounding
prong, then you must match the hot, neutral and ground (if present)
wires from the power cord to the proper connectors in the new plug.
While the device may operate no matter which one you connect, the
safety of the device may be compromised if you fail to properly match
the hot lead to the narrow prong on the new plug. The wide prong is
always neutral and so the neutral lead should be connected to it. If
the wires are color coded, in the U.S., white is typically neutral,
black or red is hot and green is ground. If you are unable to determine
which wire is which, refer to the old plug. Match up the power cord
with the old plug and follow the wire that leads to the narrow prong.
You can also test the device with ohm meter to find which wire connects
to the switch. The hot wire should be the switched wire.
Slip the wires through the back of the plug and pull them through
to the front. Once you have the plug semi-assembled, cut off any excess
wire length that will not be needed. Excess wire may make reassembly
difficult or may result in wires that protrude from plug.
Using wire strippers, strip of roughly 1/2 inch of insulation to
expose the metal wire.
If the wires are stranded, twist the strands.
Connect the hot wire to the narrow blade prong, the neutral wire
to the wide blade prong and the ground wire the rounded blade prong.
Make a small loop and place it clockwise under the screw terminal
so that when the screw is tightened it will draw the wire in rather
than push it out. Now tighten down the screw. Repeat for each wire.
Here is an example of why it may matter which wire is connected to which prong in the plug. Consider a lamp; the wiring is as follows. One wire connects to the switch, a wire connects the switch to the socket and then a wire from the socket returns to the other prong in the plug.
Electricity should flow in through the hot wire to the switch. If the
switch is off, and you were to stick your finger into the light socket
(you shouldn't, didn't your mother teach you that?)
you should not get a shock, because the switch has interrupted the flow
of current. It never gets to the socket and thus does not get to you.
What if the plug was misfired and current flowed in through the other
wire (neutral), then it would flow to the light socket then out to the
switch. If the switch is off, the light would be off. But if you were
to stick your finger in the socket this time (didn't we already tell
you not to do that?) the current would flow into your finger, through
you and into the ground. In other words, because you are grounded, current
would flow and shock you.