# Dont know how to wire a start/stop switch to motor



## humberguy

im trying to understand the concept of physically wiring a start/stop switch with a relay to control a motor. I cant find any diagrams on google or on the net. I find millions of ladder diagrams, but no diagrams of physically wiring the switch, relay, and motor.

Can anyone help me find any diagrams of wiring the motor controls.


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## emolatur

is this a self-contained unit where the START and STOP buttons are built into the starter/contactor, or are the buttons a seperate unit?


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## humberguy

im thinking of a seperate unit. One push button for start. One push button for stop. One relay for control, and the motor. I want to see the wiring for the motor controls but cant find any diagrams on the net.

I just want to learn the basic concept. Im not looking at 3 phase motor wiring, just a basic set up.


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## emolatur

http://wiki.owwm.com/GetFile.aspx?File=ElectricalMSWD/wiringdiagram3c.jpg


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## joed

The simple explanation.
The start switch is normally open. It goes in series withe contactor power. Push start button and contactor closes.
The stops switch is normally closed. It goes in series with contactor power and a normally open contact on the contactor. Push stop button and contactor opens. NO contact opens so contactor does close when stop is released.

Goggle 'contactor wiring diagram' and multitude of images will come up.


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## nap

emolatur said:


> http://wiki.owwm.com/GetFile.aspx?File=ElectricalMSWD/wiringdiagram3c.jpg


In emolaturs drawing, there is something that is not common practice. Generally, you would not switch the neutral. You can since all hot and neutrals would switch by the same action but it is generally not done that way in practice.



With emolatur's drawing, because it includes a neutral, that would suggest it is a 120 volt motor (could be a 277 but you usually don't see that in DIY work)


You need to be aware of what your motor voltage and due to that, your supply voltage and design your coil voltage accordingly.


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## emolatur

Actually, I had assumed it would be a 208/240V motor run from two hots - both hots are switched, there is no neutral.


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## AllanJ

A pair of momentary contact push buttons requires a locking contactor or relay. Pushing one button energizes one coil in the contactor that pulls the points closed to start the motor. Let go of the button and the contactor coil is no longer energized but the points have locked in the closed position. Pushing the other button energizes another coil in the contactor to pull the points open to turn off the motor. Now the points are locked open even after you let go of the button.

Some normally closed and normally open contactors have additional sets of points that can be wired in a fashion to make a locking contactor. Specifically another set of points closes and sustains the power to the coil after you let go of the button.

Push button switches also come in a form similar to toggle switches. Push the on button and the off button pops out and it closes the switch contacts which in turn can energize a normally open contactor (or relay) to close the points (or energize the motor directly with no contactor). Push the off button and the on button pops out and the switch contacts open and the contactor coil lets go of the points that resume their normally open position.


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## J. V.

Heres one using line voltage for the control. Stop/Start.


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## nap

emolatur said:


> Actually, I had assumed it would be a 208/240V motor run from two hots - both hots are switched, there is no neutral.


look at your pic again. It indicates L1 as a neutral based on the key provided.


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## joed

nap said:


> look at your pic again. It indicates L1 as a neutral based on the key provided.


The diagram I see is a three phase motor. There is no neutral.


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## emolatur

nap said:


> look at your pic again. It indicates L1 as a neutral based on the key provided.


Interesting point (joed: he's referring to my diagram, which I posted only as a link, not an img). I hadn't noticed that, and it does something I don't like - the STOP button switches what they have labeled as "neutral".

Just the same, if we treat it as a 240V motor and erase where it says "neutral", we're back to what I MEANT to post.



I guess it shows I need to be more careful about analyzing the details of things I find on Google before I repeat them to others


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## nap

joed said:


> The diagram I see is a three phase motor. There is no neutral.


in emolaturs link? If so, you get a different webpage than I do.









It's not that it was really wrong for the OP's question. It just switches the neutral which is unusual and only legal if done with proper respect to the code sections speaking to the matter.


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## humberguy

AllanJ said:


> A pair of momentary contact push buttons requires a locking contactor or relay. Pushing one button energizes one coil in the contactor that pulls the points closed to start the motor. Let go of the button and the contactor coil is no longer energized but the points have locked in the closed position. Pushing the other button energizes another coil in the contactor to pull the points open to turn off the motor. Now the points are locked open even after you let go of the button.
> 
> Some normally closed and normally open contactors have additional sets of points that can be wired in a fashion to make a locking contactor. Specifically another set of points closes and sustains the power to the coil after you let go of the button.
> 
> Push button switches also come in a form similar to toggle switches. Push the on button and the off button pops out and it closes the switch contacts which in turn can energize a normally open contactor (or relay) to close the points (or energize the motor directly with no contactor). Push the off button and the on button pops out and the switch contacts open and the contactor coil lets go of the points that resume their normally open position.



Thats what im getting. My question now is, when wiring the coil side of the relay. Where do the coil wires go? Do both wires go to the motor?


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## nap

humberguy said:


> Thats what im getting. My question now is, when wiring the coil side of the relay. Where do the coil wires go? Do both wires go to the motor?



look at the drawings. The coil is that circle inside the box labeled contactor and relay. Follow the wires and notice where they attach to a power source.


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## mdlewis

*start stop HELPPPPPP please*

i need a circuit to start a motor run for 5 seconds and then shut off how can i do tt


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## zappa

mdlewis said:


> i need a circuit to start a motor run for 5 seconds and then shut off how can i do tt


You are not really providing enough information.

A standard motor start contactor and an adjustable delay relay would be one way of doing this.

Or just a delay relay if the motor is small enough.


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