JohdotaA control push-button has two parts: the button head, which is fixed to the front panel, and the contact blocks that snap on behind it. A spring returns the button when it is released, so the contact changes state only while the button is pressed.
Normally open and normally closed
- Normally open (NO), 13–14. Open at rest, closed when pressed. Used for starting.
- Normally closed (NC), 11–12 or 21–22. Closed at rest, open when pressed. Used for stopping.
The stop button is an NC contact so that a broken wire or a loose connection stops the equipment. If the stop were made with an NO contact, a break would leave the equipment running with no way to stop it.
Two contacts on one button
One button can carry both an NO and an NC contact block. The button can then switch on one circuit and break another at the same time. This is used, for example, in direct reversing, where the direction is changed without stopping first.
Colours
IEC 60204-1 gives the colours for push-buttons:
- Start: white, grey, black or green. White is preferred. Red must not be used.
- Stop: black, grey or white. Black is preferred. Green must not be used. Red is allowed, but it is not recommended near an emergency stop button.
- Reset: blue, white, grey or black.
In Johdota the start button is green and the stop button is red, which the standard allows.
In your region
Showing notes for
UK & Ireland
Machines in Great Britain are built to BS EN 60204-1, the European version of IEC 60204-1.
Source: UK government: designated standards for machinery (list v16, 2026)
Europe
Machines in Europe are built to EN 60204-1, the European version of IEC 60204-1. It is a harmonised standard under the Machinery Directive.
Source: European Commission: harmonised standards for machinery (summary list) · DIN Media: EN 60204-1:2018+A1:2025
Australia & New Zealand
Australia and New Zealand use AS/NZS 4024.1204, which is IEC 60204-1:2016 with national modifications.
Source: Standards Australia: AS/NZS 4024.1204:2019 (IEC 60204-1:2016 MOD)
United States
NFPA 79, the US standard for industrial machinery, prefers green for start and red for stop. Black, white and grey are allowed for both, but red must not be used for start and green must not be used for stop. So the green start and red stop buttons in Johdota are the preferred colours here.
Source: NFPA 79 First Draft report, 2026 cycle (shows the 2024 text of 10.2.2)
United States, Canada
On ladder diagrams a pushbutton is marked PB, or with its function, such as START and STOP. A number tells several apart, for example 1PB and 2PB.
Source: Siemens: Basics of Control Components, part 1 (STEP 2000 course) · NFPA 79 First Draft report, 2024 edition (13.2.3, Annex E Table E.1 device designations) · Square D (Schneider Electric): Wiring Diagram Book 0140CT9201, symbols and examples · Evolution Motion: JIC standard graphic symbols for electrical ladder diagrams
Canada
Industrial machinery in Canada is covered by CSA C22.2 No. 301. We have not been able to check its pushbutton colours. In the USA, NFPA 79 prefers green for start and red for stop, and allows black, white and grey for both. If you know the Canadian rule, please send feedback.
Source: Standards Council of Canada: CSA C22.2 No. 301:23 Industrial electrical machinery · NFPA 79 First Draft report, 2026 cycle (shows the 2024 text of 10.2.2)
Other IEC countries
No regional notes on this page yet. If something is different in your country, please send feedback.
Frequently asked questions
How do you wire a push-button?
The start button (NO, 13–14) goes in the supply to the contactor coil, usually in parallel with the holding contact. The stop button (NC, 11–12 or 21–22) goes in series with the control circuit, so pressing it breaks the coil circuit.
What is a normally closed push-button?
A button whose contact is closed at rest and opens when pressed, usually 11–12 or 21–22. It is used for stopping, because a broken wire or a loose connection then also stops the equipment.
What is the difference between a normally open and a normally closed push-button?
An NO contact (13–14) is open at rest and closes when pressed. An NC contact (11–12 or 21–22) is closed at rest and opens when pressed. NO is used for starting, NC for stopping.
Which contacts do start and stop push-buttons use?
Start uses an NO contact, usually 13–14. Stop uses an NC contact, 11–12 or 21–22. With an NO stop button, a broken wire would leave the equipment running with no way to stop it.
How do you wire an illuminated push-button?
The contact and the light are separate. Wire the contact like an ordinary push-button, and the light from its own terminals X1–X2, like an indicator light.
What colour should a start push-button be?
IEC 60204-1 allows white, grey, black or green for start buttons, with white preferred. Red must not be used for a start button.
What colour are stop and reset push-buttons?
Under IEC 60204-1, stop buttons are black, grey or white, preferably black. Green is not allowed. Red is allowed but not recommended near an emergency stop. Reset buttons are blue, white, grey or black.
Sources
- Schneider Electric: push-button colours in IEC 60204-1 (2021)
- Sprecher + Schuh: auxiliary contact terminal markings 13–14 and 21–22
- UK government: designated standards for machinery (list v16, 2026)
- European Commission: harmonised standards for machinery (summary list)
- DIN Media: EN 60204-1:2018+A1:2025
- Standards Australia: AS/NZS 4024.1204:2019 (IEC 60204-1:2016 MOD)
- NFPA 79 First Draft report, 2026 cycle (shows the 2024 text of 10.2.2)
- Siemens: Basics of Control Components, part 1 (STEP 2000 course)
- NFPA 79 First Draft report, 2024 edition (13.2.3, Annex E Table E.1 device designations)
- Square D (Schneider Electric): Wiring Diagram Book 0140CT9201, symbols and examples
- Evolution Motion: JIC standard graphic symbols for electrical ladder diagrams
- Standards Council of Canada: CSA C22.2 No. 301:23 Industrial electrical machinery