converting two prong plugs to three prong

[dalangdon]

I am (hopefully) picking up the Coldspot freezer today, and one of the first things that needs to be done is to replace the very crinkly power cord.

Right now, it is a two prong cord, and most appliance cords are three prong. Is it appropriate and/or OK to just ground the third wire to the frame, or should I try to find a two prong cord?

 

[Unimatic1140]

Hi Dan, yes I do this all the time. Just connect the green wire of the new 3-prong cord to a metal part on the frame.

This is a great way to safely update all your vintage major appliances.

 

[panthera]

Dan,

I agree with Robert. You should, however, remember to ground every single electrical device (motor, relays, etc.) in the machine to the frame or (much better) to a central grounding point which also includes the frame.
And don't forget that most condensers older than a few decades are going to be leaking to ground...so don't be surprised if the first time you plug in a truly grounded machine the fuse blows.
I also make a point of grounding the frame to the cold water supply lines. This gets around the dratted "classic bridge" problem or a high-ohm grounding point.
(Classic bridge is the German term, I don't know the English -the Neutral connector and ground are connected. Anyone know the English word for it?)

 

[dalangdon]

"You should, however, remember to ground every single electrical device (motor, relays, etc.) in the machine to the frame or (much better) to a central grounding point which also includes the frame."

I'm afraid that is *way* beyond my mechanical ability (not to mention my emotional capacity ;-)

Will it damage/threaten anything if I don't do that?

 

[panthera]

Dan,

No - and I apologize for making something very simple sound very complex.
May I try again?
We ground things to keep us from getting killed or the house burning down when something goes wrong with the machine.
If you hook up the ground wire from a three prong cord to the frame, you have taken a big step towards safety.
I live in a country which uses 230V for normal things like toasters and mixers and washers...so we tend to be a little cautious.
What I was - badly - explaining was the following:
Your washer has an electrical motor. A timer motor. A set of solinoids to let water in. Maybe a light, sorry, I don't remember. There is also the control panel.
A "perfect" grounding job would mean running a wire to each of these from one big grounding nut and bolt, where you have attached the ground wire from the three prong plug.

Sometimes, when you ground an older machine, the fuse blows immediately. This could be caused by any of the things I just listed - or a little thing called a capacitor or condenser. These "help" the motor run when it gets started. They wear out once they get past 30 or so (sort of like men) and often make the fuse blow. The solution is simple - have this little part replaced. They carry a big jolt of electricity - even unplugged - so you might want to have this done by an electrician.

I hope this helped. Sorry to be so confusing.

 

[sudsmaster]

Classic bridge

Not familiar with the term classic bridge, but a couple of things to avoid are the floating ground and the ground loop.

In a floating ground, there is not a connection between the appliance(s) and earth ground. This is probably typical of older appliances with two-prong plugs. Changing to a three-wire cord and attaching the ground wire to the appliance frame will likely resolve this problem.

In a ground loop, there are multiple paths to ground. This is typically an issue in public address or complex home theater systems where different components are connected to different outlets. Then, a ground potential can exist due to multiple grounding points being used.

In residential home wiring in the US, the neutral and the earth ground are connected at one point - the main panel. It is not a good idea to connect them anywhere else, because of the possibility not only of ground potentials but also of the fact that various electrical devices can put electrical noise onto the neutral wire, creating a potential to ground.