Need help wiring a foot pedal into a 220 line going to stationary sander

[Mark R Webster]

I am trying to add a foot “on and off” switch to my 220 line going from the wall to my stationary sander. I have 2 hots and 1 ground coming from the wall. The foot switch (designed for 110 or 220) has 3 wires, a black, a white and a green. Do I take one of the hots from the wall and connect it to, say, the black going to the switch and attach a second wire to the white coming from the switch and continue the second wire to the terminal/tool where the hot would have gone if I were not using the switch? I assume the ground wire from the switch would be added to the ground coming from the wall heading to the tool?

[Mike Henderson]

I'm going to guess from your description that your foot switch is a "single pole, single throw" (SPST) switch. You can use an Ohm meter to check continuity when you press the switch.

If it's an SPST, I'd use it to control a 120 volt DPST contactor, which would control both sides of the 240 volt line. While opening one side of a 240 volt line will stop the machine, it leaves the other (hot) side of the 240V line connected to the machine.

Mike

[Mark R Webster]

This is the switch. https://www.ssccontrols.com/product/...h-front-hinge/

[Bill Dufour]

This is the switch. https://www.ssccontrols.com/product/...h-front-hinge/

They show the internal wiring diagram. It is a single pole switch only rated for ten amps. How many amps on your motor? If you have a switch upstream of this one it may be okay if your shop is not inspected.
Bill D.

[Mark R Webster]

The tool is rated at about 7 amps using 220

[sean meltvedt]

Mark, follow Mikes advice and use a contactor (aka big relay) to open both legs. You really don’t want to leave one powered, it could cost you everything!
cheers
Sean

[Rollie Meyers]

It is code compliant to only break one leg of a 240V circuit as long as it is not the disconnect, which a foot switch cannot be. The practice of only breaking one leg of single phase, or 2 legs of 3 phase 240V loads is pretty common. I don't particularly care for it but from a code standpoint, it's permitted. A 220V circuit has 1 hot leg, and a neutral, and is 50 Hertz, and is the norm in most of the world outside of North America.

[Curt Harms]

I'm going to guess from your description that your foot switch is a "single pole, single throw" (SPST) switch. You can use an Ohm meter to check continuity when you press the switch.

If it's an SPST, I'd use it to control a 120 volt DPST contactor, which would control both sides of the 240 volt line. While opening one side of a 240 volt line will stop the machine, it leaves the other (hot) side of the 240V line connected to the machine.

Mike

What he said. I've used special purpose contactors that can be purchased pretty cheap and put in an electrical box. You don't need the overload protection that is part of a starter, do you?

[Jim Becker]

Mark, follow Mikes advice and use a contactor (aka big relay) to open both legs. You really don’t want to leave one powered, it could cost you everything!
cheers
Sean

I agree. A contactor is the safest way to handle this and the foot pedal can be low voltage for control.

[Mark R Webster]

I am sorry Mike I am having a hard time understanding what is being recommended. I am not familiar with a 120 V DPST. Again I am not an electrician... are you suggesting I can use the pedal I have, but for safety I need to install a 120 volt DPST contactor in the line? Would it be:
Wall >SPST pedal> 120 volt DPST contactor> machine
or
Wall > 120 volt DPST contactor> pedal> machine?

Can someone point me to a link for one of these contactors? Is the contactor also called a relay? How can one put a 120 device in a 220 system?
Are you guys saying that "technically" I could wire as I described in my first post but it would be dangerous because with the pedal in the off position, one of the wires heading to the tool is still hot. Note, there is an on and off switch on the tool that would come after the foot pedal switch. So if wired as I described initially, the hot portion of the line (pedal in the off position) would be between the pedal and the tool in front of the tool's on and off switch.
Sorry for being dense on this.

[Joe Kaufman]

In addition to the problems listed above, is this what you really want?
It will only be on as long as pressure is applied to the foot switch.

From the wiring diagram - "

Action:

momentary (press and hold to turn on, release to turn off)"

I would consider adding a warning light to indicate the foot switch is hot meaning it will start the machine.

You should also consider a guard over the switch to prevent accidental activation.

[Mark R Webster]

My understanding was this pedal was not a "momentary" type in the description it says:

"Action: maintained (press once to turn on, press again to turn off)"

[Jim Becker]

Mark, a contactor is like a relay if it helps you understand it's function as a switch. It has two sides...control and line. The line side has to be rated for the voltage and amperage for the tool to be switched. The control side can be low voltage or 120v AC, depending on what you buy. Here's a graphic of how I use a contactor for my cyclone...the theory would be the same for your tool with your foot pedal replacing the wall switch I use for my setup.

[Joe Kaufman]

Mark, your link goes to a S400-1002 which is a momentary type.

[Mark R Webster]

Sorry Joe, my error I meant it to go to the the other pedal.