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I want to wire an emergency shutoff button to switch off the circuit of one room.

While I understand what to do in theory, I am not quite sure how exactly the button needs to be wired.

It is one of these that needs to be pulled out manually and stays there until pressed or power runs out, so the machines also don't restart if the power was cut externally and comes back.

It has 4 terminals, and I suppose I need to connect it to neutral, incoming phase and the outgoing phase (which is going to the switch,) but am unsure of the exact wiring.

I suppose to do it safely I need a 5-wire cable between the button (which is on a central location in the room) and the switch (which is at the position where the power is coming out of the wall,) so I can send both phase wires over it without "relabeling" a ground wire as phase.

I made some pictures of the switch, maybe it's more clear from them. Also, I am from Germany (I know there are some local laws/rules regarding that.) That combination of switch/button has worked before, but unfortunately I did not remember the exact wiring.

JRE
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Boldar
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    [What to check for when buying an electronic component or module](https://electronics.stackexchange.com/questions/504044/what-to-check-for-when-buying-an-electronic-component-or-module) - link to the data sheet please. – Andy aka Jun 20 '20 at 10:43

3 Answers3

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The emergency latching push button switch, also known as a mushroom push button switch (Pilz Schaltgerät), is used to cut off, through it's NC contact, electrical power to a machine / electrical equipment under an emergency situation, to avoid injury to personnel or damage to the equipment.

The mushroom button S0 is released, by rotating it, when the fault is cleared.

enter image description here

To ensure that the equipment does not restart immediately after the mushroom button is released, a 'zero-volt safety' feature is provided.

The 'zero-volt safety' feature ensures equipment restart only after a start button S1 is actuated. This feature also prevents the equipment from automatically restarting after power is restored after a failure. The function is performed by an electromagnetic relay K0. The NO contacts of K0 switch on the power to the equipment.

In equipment where there is a higher risk of injury to personnel, the single relay K0 is replaced by a 'Safety Relay' (Sicherheitsrelais), with dual redundancy, to ensure fail-safe operation.

For your purpose, it would suffice to wire the NO contacts of K0 in the lines powering the circuits of the room.

vu2nan
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Your switch has one set of normally open contacts ("schliesser") and one set of normally closed contacts ("öffner.")

The switches are marked "NC" for "normally closed" and "NO" for "normally open."

You should use the NC switch to switch the hot wire to your relay. The relay coil gets neutral and the switched hot from your emergency button.

You use the NC contacts so that power gets switched off if something breaks the emergency switch circuit - broken wire, fire, etc.

JRE
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The sketch below shows one possibility. The emergency stop shutoff button is marked "Lockout E-Stop." When pressed, the top contact opens and the bottom contact closes. The top contact stops the machine and prevents it from being restarted until the button is pulled out.

The bottom switch closes when the button it pushed and remains closed to turn on a light to indicate that the machine has been locked out. This function is optional, but is one explanation for four wires on the e-stop rather than two. Only one additional wire is required for this function as shown. It might be wired somewhat differently, or the forth wire might have another function. The button does not need a neutral wire, but it might need a ground wire.

The start and stop buttons are momentary-contact switches. When the start button is pushed it energizes the contactor coil. The small normally open contact of the contactor then bridges the start button connection the keep the machine running after the button is released. If the power goes off, the contactor opens. It does not close when the power returns because the start button is no longer bridged. For normal stopping, the stop button needs only to be opened long enough for the contactor to open the bridging contact.

enter image description here