electrical grounding, electrical wiring, how to ground an appliance that doesn't have a ground, how to replace a two-pronged cord with a three-pronged cord, rewiring an appliance, where to attach a ground wire in an appliance, william beatty
Hubby and I bought a stand mixer that had a seriously frayed cord.
It was obvious that we were going to have to replace the cord in order to safely use the mixer.
This cord had a two-pronged plug, which meant that the mixer was not grounded. Because we are safety conscious people, we thought it would be nice to replace the cord with one that had three prongs, in essence giving the mixer a ground.
For those of you who have never done wiring, in the United States most wiring now comes with three strands of copper wire inside a larger piece of rubbery insulation. Each strand is wrapped in a separate color insulation, black for the “hot” wire (this denotes power coming from the electrical service box), white for the neutral wire (this denotes power travelling back to the electrical service box), and green for the ground or “earth” wire. The ground wire is connected to the ground or earth, typically by attaching it to a metal cold water pipe. The ground allows an excessive electrical current, say, from a lightning strike or power surge, to discharge safely into the ground, rather than zap electrical appliances or human beings in the current’s path. This web page by William Beatty does an excellent job of explaining electrical grounding.
Old wiring and current two-pronged plugs only have the black and white wires, not the ground, like our stand mixer.
There is supposed to be a safe way to replace a two-pronged cord with a three-pronged one, but the key is knowing exactly where to attach the ground within an appliance. If an appliance already has a three-pronged cord, the manufacturer supplies the proper place to attach the ground, so replacing each wire is a matter of detaching each old wire (black, white, green) one at a time and replacing each with the appropriate strands of the new plug-in wire.
In an appliance with only two prongs, and, thus, only a black and white wire, there is no specific place to attach the ground wire from a three-pronged plug. We had heard that the green wire could be attached to the frame of the machine in order to ground it, but I wasn’t comfortable not know EXACTLY where it should go.
SAFETY LESSON HERE: When it comes to electricity, your life is on the line, so if you have no idea what you are doing, contact a knowledgeable electrician to get advice, or pay one to rewire your appliance. Also, before rewiring an appliance, make sure it is unplugged.
We’ve done quite a bit of wiring, like most of our house (it passed inspection by a tough electrical inspector), so we thought we could figure this out. I went online and searched and searched for an answer on how to replace a two-pronged plug-in with a three-pronged one, specifically on where to attach the ground wire to the appliance and guess what? I couldn’t find an answer online.
We rewired the cord, attaching the ground wire to a screw on the motor. Erik plugged the machine in and ZAP! The circuit breaker tripped and there was a sizzle and a little smoke from the machine.
Obviously, we had not wired the machine properly. Thankfully, Erik had not been touching the machine when he plugged it in. Again, thankfully, the circuit breaker did its job and immediately shut off. We had to hope we didn’t burn out the motor.
I went online and did more research. I figured we had done something wrong with the ground because every other wire was meticulously replaced one at a time. That’s when I found the web page I linked to above. It seems that where we had attached the ground to the motor caused electrical confusion among our wires, which shut off the circuit. (If a licensed electrician is reading this and can clearly explain what happened, please do so in the comments.)
Because we couldn’t find an answer to where to attach the ground wire inside the mixer (I even looked for answers in, gasp, books!), we decided that the safest course of action was to remove the three-pronged cord and rewire the appliance using a new two-pronged cord.
After this, the mixer works like a charm. No blown motor, no electrocuted people.
I wasn’t necessarily going to blog about our stupidity with electricity, except that it really bothered me that we couldn’t find an answer to our question online.
My answer to the question, “How do you replace a two-pronged cord with a three-pronged cord?”: DON’T – unless you’re a licensed electrician and/or know exactly what you are doing.
Instead, replace a two-pronged cord with a two-pronged cord and replace a three-pronged cord with a three-pronged cord. Make sure the cord you are replacing has a similar gauge (size) to the old one. If you don’t know, ask for help!
To any electricians in the audience, there is room on the internet for a good, easy-to-find wiring blog if you have the time and inclination. (Although, come to think, you probably don’t want the liability.)