Plug question

S

Stickypoint

Joined
Apr 2, 2000
Messages
45
Just got a new grinder but it didn't come with a plug. It's a 220V variable speed motor. The cord has a black, white and green wire. Can somebody tell me which is the hot, neutral and ground ???

As I understand it if I hook the hot and neutral up backwards the motor will run in the opposite direction and all I will need to do is reverse it. So I guess the real question is which is the ground ?
 
Black and white are hot, green is the ground. Both black and white are current carring conductors. It dosent matter on single phase 220v which wire goes on which blade screw,except the ground needs to go on the green colored screw.Be sure and check the nomanclature/ schematic on the cover of the pecker head/junction box of the motor to make sure the motor is wired correctly for 220 v hook em up.Some times things dont come from the factory as they say they are. If the motor is wired for 110 v it wont be a pretty site if you wire the cord cap for 220v. It will smoke test and probably run for a short time at a bizillion rpm! Better get an electrician if you no savy pecker head wiring. There is no neutral Unless it is a 4 wire system for 220 v. in which case there would be 4 conductors sticking out of the cord. Hope this helps and ya dont smoke your high dollar motor/controller. Better get an electrician! Good luck! :D
 
GET AN ELECTRICIAN ! This is not a learn by experience area.Reversing the black and white wires will not make the motor run backwards (unless you are on DC).However making the wrong connections can make you run like hell.
 
Stickypoint said:
Just got a new grinder but it didn't come with a plug. It's a 220V variable speed motor. The cord has a black, white and green wire. Can somebody tell me which is the hot, neutral and ground ???

As I understand it if I hook the hot and neutral up backwards the motor will run in the opposite direction and all I will need to do is reverse it. So I guess the real question is which is the ground ?
Click to expand...

As said before, the black and white are your current-carrying llines and the green is ground. Most NEMA-rated plugs today will have a brass screw for the black wire, a chromed or steel-colored screw for the white, and green screw for the green. Pretty simple.

Determine how much amperage your motor draws, and that will determine how many amps your plug should be rated for. Most state codes require your circuit to be rated 20% higher than the load being drawn. In other words, lets say your motor draws 16 amps at full load, you would barely be able to squeak by with a 20 amp breaker, and a plug/receptacle rated for such. This will probably be fine, since you may not ever need to run your new KMG full-out, or bog it down to the point it will stop, and therefore spike your amps through the ceiling.

Once you determine this, the rest is easy, but I wouldn't recommend wiring the circuit from the service panel yourself unless you get some help. ;)
 
What Jeff said. Geeze....if you get an electrician every time you need to put a plug on, you'll go bankrupt.

On an AC, single phase circuit, the motor will run the same direction no matter which way the white/black wires are attached. There are some concerns about chassis hot on some types of equipment and in certain environments. However.....wire it the way Jeff said and you will be fine regardless. Don't forget your ground though.

Bladsmith....I had to take Electronics in High School. Now granted, that was in the pre Soccer Mom days but it was still designed to NOT KILL YOU.

One of the first things that we had to do was go to a step circuit board that Baldy Huffman (Instructor) had made. It had lugs that stepped AC from 0 to 220. We had to touch every lug to see what it was like to get a full voltage zap.

I don't recall anyone enjoying it but no one died either. I do call that a learn by experience Session. I test circuits almost daily by slapping them with one finger to see if they are hot.
While safety is an issue. Let's not get carried away!
 
peter nap said:
Bladsmith....I had to take Electronics in High School. Now granted, that was in the pre Soccer Mom days but it was still designed to NOT KILL YOU.
Click to expand...
Don: Come on!!!! They didn't have electricity way back then. :eek: :p ;) :D
 
Sorry Peter,But I was going on the info given by Stickypoint.If he didn't have any basic knowledge of wiring,he could burn up a new motor in 1/60 th of a second.,not to mention harming himself.I have known several people who slap test circuits,one of them has no middle finger on his right hand.The stuff I worked on for the govt. would kill you quick if you didn't know what you were doing.I have seen a man burned beyond recognition.Believe me- it can kill you.
Getting an electrician can mean getting a friend who knows how to wire the plug and socket.
 
There are special plug configurations for 220V circuits to prevent the machine being plugged into the wrong voltage, use the proper configuration.

With a three wire system the hookup at the wall must have 220V between the black and white terminals. Obvious of course but if you go back to the main panel you will find the voltage between the black and white side is only 110V, the line feed must be taken from two points with 220V between them.

In a properly wired panel the whites will be connected to one panel and the blacks to the fuses or circuit breakers and are considered "hot". There will normally be two lines of fuses in the panel, left and right sides, if you check the voltage from one side to the other where the black wires are connected there will be 220V.

Reversal of the motor direction will be done at the VS control box if necessary and is independant of the feed lines.
 
I know that the question didn't inspire a whole lot of confidence in my abilities but with all of your help I was able to get it working. Nope, didn't burn the motor up and didn't injure myself. (unlike when I work on knives)
I"ve never had a variable speed grinder before so it should be fun ssing how it works.
Thanks again for the help.
 
peter nap said:
by experience Session. I test circuits almost daily by slapping them with one finger to see if they are hot.
While safety is an issue. Let's not get carried away!
Click to expand...

Mostly I do my own work too, and you can't always pay an expert. Just a little TRUE story though.......

A Navy electrician, getting trained, used his volt/ampmeter in class, to check the resistance in his body. Everyone did. Later, in his bunk, he decided to REALLY check it. (he knew skin has great risistance to current flow. Anyway, he put two tiny cuts on each index finger, and stuck the probes in. As you know blood is a GREAT conductor. He died. The 9V batt stopped his heart. It went in through one arm and out the other, with the heart muscle getting all the micro amps available. Don't remember the exact current. It was surprizingly low.

So yeah, I agree that most stuff is pretty safe if you watch what you're doing. But even a tiny current will kill if it goes to the right spot.

I was wiring up my welder at the breaker box and "thought" I had the current off. But, there was an extra breaker down low that wasn't in line with the main switch. I melted my screwdriver before I could get my hand away. (I had put the other hand in my pocket for obvious reasons). I got it done, but did some serious research after...........
 
Warrant, I understand your point and I did not intend for anyone to take my post as authority to leave their common sense at home. Your story about the Navy electrician only proves that nature does have a way of cleaning up the gene pool despite OSHA.

The original question was a simple one concerning putting a plug on single phase 220. Now 220 is nothing but two legs of 110 and a neutral.

It will not run backward of wired back wards, it is very near impossible to burn that motor up unless you only hook one leg and try to run it and while AC jolts to a poorly grounded appendage is unpleasant, it is not normally dangerous.

We have gotten so safety conscious that many people shy away from doing anything for theirself. I come from the country where everyone canned. If you read modern canning instructions, you would assume that it is the most inherently unsafe practice in existence.

I handload....some of the safety warnings are frighting...and many of them are untrue, for instance the old wives tale the powder manufacturers put out about small charges of slow powders in larges cases, detonating. Never happened, can't happen and is based on a theory about heat/pressure+faster burn time.

My point is: we need to take care of our own issues based on sound judgment and all the information possible.

Just to give an example, I bought replacement heat pump last year by going into the suppliers outlet and saying I was a delivery for Nap's Heating and AC.

I paid cash.

I had already read all the training manuals and replaced my own heat pump, bought some gages, bought freon on the black market. It works like a well made watch. I didn't die from freon poisoning :eek: or electrocute myself, the economy didn't collapse because I lied to the supplier and aside from the normal hole in the Ozone layer (From killer whale farts...another story) the ecology is fine.
 
peter nap said:
Warrant, I understand your point and I did not intend for anyone to take my post as authority to leave their common sense at home.
Click to expand...

I had no intent to disparage you at all, brother, and hope you hear me loud and clear. I'm "with" you in regards to doing your own work, too. I've paid too many "experts", and had to re-do their work after they left to doubt it. a man will do so much better work, if he doesn't have to watch the clock, and the boss, and it's his own stuff he's working on.

And you're right, the question was simple and you gave an accurate answer. EXCEPT the case where some yahoo wired it in a hurry, and didn't use the right color code. Only then does knowing what you're doing make it life or death. I like wiring from the box because I 'control" what is happening after that. The guys that just use an adapter to their drier plug is what worries me. A range plug, with both 120 and 240 is even worse. But, I will say, that if a guy comes here and asks BEFORE he plugs it in, will get it right. (usually)

My point was for just those guys that want to short cut anything to get something running........You know the type:) I'd hate to heat treat a new guy before he grinds something, right?:)
 
peter nap said:
The original question was a simple one concerning putting a plug on single phase 220. Now 220 is nothing but two legs of 110 and a neutral..
Click to expand...

Sorry, Peter, but I overlooked this one. 220 is NOT 2 legs of 110 and a neutral. It's 2 legs of 120, and a GROUND. The neutral is not used except in cases where you want both 220V and 110V. Then you need 4 wires.....2 for the hots, 1 for the neutral, and 1 for the grounding.

If you use the neutral, you have NO protection against a short to the frame of your motor. YOU will be the ground, then......

Yes, the neutral is tied to the ground with a busbar at the box, but it serves opposite purposes. It's only tied together to give the breaker time to react and break the connection. I'm no expert, though, and can't give much more of an explanation. Maybe this will help....

At the transformer (pole), you have 3 wires coming to your house. 2 legs of the 110 and the neutral. The grounding wire is grounded there, and at your box, the service entrance. For 110V, you need 1 hot and the nuetral PLUS a ground. For 220V you need both hots and a GROUND, not the neutral. If a short circuit shows (loose wire, or brushes, or whatever), then the current goes from the short, through the ground, tripping the breaker. Leaving you alone. If you use a nuetral, then it goes from the short to whatever has the least risistance at the TIME> Forever. Maybe it rains next Monday and you are barefooted. Then you get to be the ground. But the breaker won't trip, as the neutral you used was plenty conductive to allow this to flow.....Anyway, you get my point.........
 
Peter,

I too took electronics in high school (over 40 years ago) and have been an electrician for over 30 years (licensed journeyman in the States of Idaho, Oregon, and Washington).
Your total lack of respect for AC is quite alarming! 110 volts ac is a killer! It can take as little as 5 miliamps (5/1000 of an amp---avery small charge) going through your heart to kill. Many people are killed each year with 110 vac. DO NOT TOUCH!!! You may get away with it a thousand times (not likely) but the very next time your heart will go into fibrilation and you die.
Remember back to your high school electronics class and I'm sure you will remember that it is AMPERAGE that kills and not the voltage. All that is required is that there be enough voltage present to over come the body's resisitance then the current will kill you. 110 vac is way more than is needed for this. Just a brief moments contact is all that is needed.
When your teacher had you touch the various lugs to get the feel of the voltage he had to have had a low current power supply feeding the lugs or he was in way over his head and should have been teaching phys ed!
Your touching AC circuits to test for voltage is a fools game that can kill you! You have been lucky that the current did not go through your heart or you would not be here today.
Peter, I do not wish this to be taken as a personal attack. I simply do not wish to see you or anyone else get killed---this is very serious stuff! If I have offended you in any way please accept my sincere appolgies, all I am concerned with is your safety.

Mike
 
Don't worry Mike, It's almost impossible to offend me. I'm just fussing about our new safe society. I get this way after a bad week! :D
 
Warrant.
Do you have any references to how that Navy student died?
Regards,
Greg
 
Everything Mike said,twice.Sorry,peter,but in this case you are just plain wrong.
Ripper - When I worked for NAVALEX I heard the same basic story.I tend to believe it is an electronics (urban) ledgend.The point is good,though.Even relatively small doses of current can kill you.
 
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