Wiring E-stop

Lay95 · May 21, 2021

Hi All,

I have a panel where 600VAC is step down to 120VAC and I have wired start, stop & E-stop button on this panel. (The panel contains transformer, circuit breaker, motor contactor and motor overload). (start & stop is used to operate motor contactor)

Now I have a small JB on field which has same start, stop & E-stop button (i.e. on the above mentioned panel) but I am confused how to wired it so that they worked from both the side.

Please provide your suggestions!!

Thank you.

JordanCClark · May 21, 2021

https://opentextbc.ca/basicmotorcontrol/chapter/three-wire-with-multiple-push-buttons/

EDIT: To add, the e-stop buttons are wired in series (I assume to a safety relay, but it's not mentioned in your post).

Lay95 · May 21, 2021

JordanCClark said:
https://opentextbc.ca/basicmotorcontrol/chapter/three-wire-with-multiple-push-buttons/

EDIT: To add, the e-stop buttons are wired in series (I assume to a safety relay, but it's not mentioned in your post).

Thanks Jordan.

My main concern is running an extra cable and how to wired it or configure it in a right way.

I understand that we can connect the two E-stop button in parallel. But one is on the panel and the other is on the field at a distance of 50-60 feet from panel.

And by the way, I like your signature!!

saultgeorge · May 21, 2021

Lay95 said:
Thanks Jordan.

My main concern is running an extra cable and how to wired it or configure it in a right way.

I understand that we can connect the two E-stop button in parallel. But one is on the panel and the other is on the field at a distance of 50-60 feet from panel.

And by the way, I like your signature!!

Hi, I've never seen E-Stop or any stop in parallel. That won't work. When you wire the remote box, and I'm presuming this is a 3-wire control circuit, you want both (or n.. of E-Stops) wired in series and the start buttons wired in parallel. You can google images of basic control circuits with remote Start/Stops and see how it looks on a print and then wire it accordingly. Hope this helps.

JordanCClark · May 21, 2021

saultgeorge said:
You can google images of basic control circuits with remote Start/Stops and see how it looks on a print and then wire it accordingly.

Or use the link I provided.

jets · May 21, 2021

I thought an e-stop removes control circuit power in most cases. Wire the two e-stops in series and interrupt L1 or the 120 VAC of the control circuit...

GaryS · May 21, 2021

A lot will depend on you local codes and regulations.
on a new installation to be labeled an E-Stop it must be connected to a monitored safety relay depending on the class of the installation you may be able to get away with a single loop circuit. for me I always us the 2 loop configuration then I know I am covered the only additional cost is the wire
it would be best to have all your controls at 24V then you could run then all in the same conduit.

Lay95 · May 21, 2021

saultgeorge said:
Hi, I've never seen E-Stop or any stop in parallel. That won't work. When you wire the remote box, and I'm presuming this is a 3-wire control circuit, you want both (or n.. of E-Stops) wired in series and the start buttons wired in parallel. You can google images of basic control circuits with remote Start/Stops and see how it looks on a print and then wire it accordingly. Hope this helps.

Thanks George,

My bad, I mean in series instead of parallel.

Lay95 · May 21, 2021

jets said:
I thought an e-stop removes control circuit power in most cases. Wire the two e-stops in series and interrupt L1 or the 120 VAC of the control circuit...

Thanks Jets

Lay95 · May 21, 2021

GaryS said:
A lot will depend on you local codes and regulations.
on a new installation to be labeled an E-Stop it must be connected to a monitored safety relay depending on the class of the installation you may be able to get away with a single loop circuit. for me I always us the 2 loop configuration then I know I am covered the only additional cost is the wire
it would be best to have all your controls at 24V then you could run then all in the same conduit.

Thanks Gary.

"It must be connected to a monitored safety relay" (I didn't get this).
I guess single loop circuit is okay compare to 2 loop configuration as less cables running.

I have a 24VDC panel as well for controls.

jholm90 · May 21, 2021

In Ontario it is not permitted to call the device an E-Stop unless it is connected to a safety circuit with appropriate components and wiring practices. This usually requires two contacts on each button wired in series NC/Normally Closed then to a safety relay. The relay will cross check that both contacts were opened and closed within a certain amount of time (0.01s for example. Any issues with this or crossed wires will prevent the relay from energizing and will require resetting the fault.

Also of importance it is required to have a PHSR (Prestart Health Safety Review) preformed on the machinery if safety circuits are modified after the initial buy off. This will be a professional engineer examine the safety circuits and guarding of the machine and will take legal responsibility if someone gets hurt on the machine

All of the remote estop boxes that I have installed have a 7 wire cable running to them:
1. Contact #1 in
2. Contact #1 out
3. Contact #2 in
4. Contact #2 out
5. Constant +24vdc
6. Constant 0vdc
7. Ground

I have a 3rd contact on the button that is Normally Open that is used with running a pilot light if the button is pushed, making it easier to find the problem, especially if all of the buttons are run in series.

GaryS · May 22, 2021

That's about the way I wire them except the buttons themselves don't have a ground term
I ground the panel as required by code.
if there is a PLC involved I like to bring an N.C. contact back to the plc and display on the screen what E-Stop has been activated it saves the operator time not having to run around and find the Correct E-Stop

Lay95 · May 27, 2021

jholm90 said:
In Ontario it is not permitted to call the device an E-Stop unless it is connected to a safety circuit with appropriate components and wiring practices. This usually requires two contacts on each button wired in series NC/Normally Closed then to a safety relay. The relay will cross check that both contacts were opened and closed within a certain amount of time (0.01s for example. Any issues with this or crossed wires will prevent the relay from energizing and will require resetting the fault.

Also of importance it is required to have a PHSR (Prestart Health Safety Review) preformed on the machinery if safety circuits are modified after the initial buy off. This will be a professional engineer examine the safety circuits and guarding of the machine and will take legal responsibility if someone gets hurt on the machine

All of the remote estop boxes that I have installed have a 7 wire cable running to them:
1. Contact #1 in
2. Contact #1 out
3. Contact #2 in
4. Contact #2 out
5. Constant +24vdc
6. Constant 0vdc
7. Ground

I have a 3rd contact on the button that is Normally Open that is used with running a pilot light if the button is pushed, making it easier to find the problem, especially if all of the buttons are run in series.

Thanks for the guidance.

Lay95 · May 27, 2021

GaryS said:
That's about the way I wire them except the buttons themselves don't have a ground term
I ground the panel as required by code.
if there is a PLC involved I like to bring an N.C. contact back to the plc and display on the screen what E-Stop has been activated it saves the operator time not having to run around and find the Correct E-Stop

Yes, PLC is involved but no HMI. I do ground the panel instead of the individual button.

"if there is a PLC involved I like to bring an N.C. contact back to the plc and display on the screen what E-Stop has been activated it saves the operator time not having to run around and find the Correct E-Stop"
That's right, it is a good habit to do so, I will keep in mind.

Thank you Gary.

Timbert · May 27, 2021

saultgeorge said:
Hi, I've never seen E-Stop or any stop in parallel. That won't work.

Not saying that it is/was safe. I've seen one, several PB wired in parallel to the main 480V relay via a shunt trip. Press a button and it applied 120V to the shunt trip and opened the mains power.

This was late 80's early 90's, never convinced them to replace it. Best I got was to implement routine testing of the system.

Horrible idea, all it takes is one loose connection and no more estop.

Wiring E-stop

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