electrical question

[joe zarnitz]

wiring diagram for a 220 volt switch---tks,joe

[Dennis Peacock]

Joe,

That's a little bit on the vague side. 220V switch should be fairly easy. Two hot legs from the "line" side and two hot legs going to the "load" side. Toss in a Neutral and ground....and your done. A little more detail will help us all know more about what you are asking about.

[Steve Schoene]

Where does the neutral come from? A 240v circuit has only two hot lines and a ground. There are sometimes 4 wire plugs and connections, but the neutral in that context is used to create a 120v circuit in addition to the 240v. as is called for in some appliances.

[Bruce Shiverdecker]

One thing is important! Get a Double Pole Motor rated Switch, so you break BOTH hot leads, otherwise you could "Single Phase" your motor................not a good thing to do. It has a tendency to let the smoke out of a motor. Then it won't work anymore and you have to go out and try and find a bag of smoke to put back in.

Bruce

[Dennis Peacock]

Steve,

My TS and my Jointer/Planer only have three wires to them. From the electrical panel to the outlet and then from the outlet to the machine. In a standard Single Phase residential power box, you have a ground/neutral and two hot legs. Each hot leg is 120V AC, which is why you have to have a two pole breaker. It spans both bus-bars in the panel to provide you with a combined 220V power source.

So in my case, I have two "line" leads coming in and two "load" lines going from the switch to the motor. The double pole switch is just a way to "make and break" the power source and the motor. I tied the ground from the machine to the ground going to the panel...not connected to the switch at all.

You can visit my personal web site and see my Remote Dust Collector switch I set up. The "relay" in the circuit is just a fancy-shmancey switch. Since I posted those pics, I've actuall attached the ground leads to the case of the relay box.

Clear as mud? :rolleyes:

[Dev Emch]

Joe, you need to tell us what your doing.

Personally, I would use a mag starter on a 220 volt machine tool because they often sit on concrete in the garage or shop. If its three phase, you will need a mag starter (i.e. three leg contactor relay with integral heaters) just to get it to work.

Mag starters or Motor Contractors as i call them provide you with two features. One, they reduce the startup voltage that you come in contact with. My milling machine runs on 480 volts. You want a loose wire in that machine? Two, real motor contactors have heaters or overload relays which can protect your expensive motor from overheatting itself to death.

The principle of wiring these machines up is the same for single phase or three phase when using a motor contactor or motor starter. In three phase, you have to run three wires through the relay contacts. In single phase, I have to run two through the contactor. Technically, I only need to run one. But often its cheaper to buy a three phase contactor and this will work for 220 volt single phase anyway.

NEVER RUN YOUR GROUNDS THROUGH A CONTACTOR RELAY. The ground needs to be online at all times. Not just when the machine is running.

Lastly, you can hook up your DC with nothing more than a current sensing relay. ABB owns a subdivision that makes these. A ferrite donut around one of your power leads senses current flow via the magnetic field. This then trips a reed relay which can be used to pull in the contactor coil on your DC motor starter.

You can add as many of these as you wish as they all work in parallel. The corresponding kill switches are wired in series. So when you are sawing on the table saw and you buddy or wife turns on the jointer or shaper, no worries. The relay for the jointer can do no harm as the DC pull in coil is already active.

Turning the DC off is another question. This can be done any number of ways but it will be personal preference as to what kill strategy you wish to use.