Automatic start-up
Warns that equipment can start automatically.
Understanding this sign
Yellow triangular signs draw attention to a hazard, such as electricity, moving machinery, or a hot surface.
A warning pictogram does not state the severity, safe distance, or protective measures. Read the accompanying instructions.
What W018 Warns About
W018 marks equipment that can begin moving without any operator at the controls. ISO 7010 assigns it the function of warning about automatic activation: machinery governed by sensors, timers, level switches, PLC logic, or remote commands can cycle at any moment, even when it appears idle. Classic examples are air compressors that cut in on pressure demand, sump and transfer pumps on float switches, conveyor lines restarted by an upstream controller, robot cells, and packaging machines that resume after a fault clears.
The danger W018 addresses is precisely the machine's silence. A worker who reaches into a jammed conveyor or opens a compressor enclosure sees nothing moving and assumes the equipment is safe. Because the start signal comes from logic rather than a visible human action, there is no warning cue before motion begins. The triangle tells the viewer that stopped does not mean de-energized on this equipment.
Lockout/Tagout Is the Real Control
In the United States, servicing equipment that could start unexpectedly falls squarely under 29 CFR 1910.147, OSHA's lockout/tagout rule for controlling hazardous energy. Lockout/tagout exists for exactly the scenario W018 depicts: energization or start-up during maintenance. A sign never substitutes for isolating the energy source, applying a personal lock, and verifying zero energy before body parts enter the danger zone. W018's job is to prompt that procedure, not replace it.
This mirrors the risk-reduction hierarchy in ISO 12100, where information for use — including safety signs — is the final layer after inherently safe design and safeguarding. Interlocked guards that stop the machine when opened, and control systems that require a deliberate local reset after any stop, should come first. Post W018 to cover the residual risk that remains once those engineering measures are in place.
Where to Post It
Place W018 wherever a person could reach the moving parts believing the machine is off: access doors and removable panels on compressor and pump enclosures, gates into robot and palletizer cells, conveyor jam-clearing points, HVAC plant with automatically starting fans, generator sets on auto-transfer switches, and irrigation or dust-collection systems on timers. The sign belongs on the access point itself, at the moment of decision, not only at the room entrance.
Pair W018 with the mandatory sign M021, which orders equipment to be disconnected before any maintenance or repair work, or with a supplementary text panel directing workers to isolate and lock out before servicing. On larger installations, arrows or text should identify where the disconnect is located, since a warning that cannot be acted on locally tends to be ignored.
W018 Compared With Similar Signs
W018 is often confused with W012 (electricity). W012 warns of electric shock from live parts; W018 warns of mechanical motion triggered automatically. A control cabinet may legitimately carry both: W012 for the busbars inside, W018 on the machine it drives. Likewise, W019 (crushing) or W025 (counterrotating rollers) describe what the moving parts will do to a body, while W018 explains why they may move with no one at the panel — many machine labels combine them.
Machine builders frequently apply W018 at the factory as part of the residual-risk information required with the machine's instructions under machinery safety legislation such as the EU Machinery Directive. Facility owners should not remove or paint over these labels during installation, and should replicate them on any fixed guarding or fencing added on site.
Where you will see W018
Typical positions include access doors on compressor and pump enclosures, gates into robot and palletizer cells, conveyor jam-clearing points, HVAC plant with automatically starting fans, and generator sets on auto-transfer switches. Machine builders apply it at the factory as residual-risk marking, and sites pair it with M021 disconnect-before-maintenance instructions and arrows locating the isolator.
Common questions about W018
What does the ISO 7010 W018 automatic start-up sign mean?
It warns that the marked equipment can start by itself, without a person pressing a button. Compressors, pumps, conveyors, robots, and other machines under sensor, timer, or remote control can begin moving at any time, so being visibly stopped does not make them safe to touch. Isolate and lock out the energy supply before reaching in or opening guards.
Does a W018 sign satisfy OSHA lockout/tagout requirements?
No. OSHA 1910.147 requires an energy control program with written procedures, employee training, locks and tags, and verification of isolation before servicing equipment that could start unexpectedly. The sign supports that program by alerting workers to the hazard, but posting it does not fulfill any of the standard's procedural requirements.
Which sign goes with W018 on machinery?
The most common companion is M021, the blue mandatory sign requiring disconnection from the power supply ahead of maintenance and repair, or a text panel with equivalent lockout instructions. On the hazard side, W018 is often combined with the sign for the specific mechanical injury, such as W019 for crushing or W025 for roller nip points.
What is the difference between W018 and the electricity warning W012?
W012 warns of electric shock from live electrical parts. W018 warns of mechanical motion that begins automatically. Equipment can present both hazards at once — an automatically starting pump has live terminals and a rotating shaft — which is why the two triangles frequently appear together on the same enclosure.
Reference details
| Symbol code | W018 |
|---|---|
| Sign family | ISO Warning Signs |
| Standard reference | ISO 7010:2019 / ISO 3864-1 ISO Online Browsing Platform: W018 |
| Screen color reference | #FFCC00. Screen colors are not a production color specification. |
| Download formats | SVG reference artwork; a 1024 × 1024 pixel PNG conversion on a white canvas. |
| Record date | · How to interpret our dates |
| Page updated |
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Sources and artwork credits
- Artwork source
- Wikimedia Commons file page
- Creator credited by source
- MaxxL
- License
- Public domain
- Source metadata checked
SVG files are local reference copies. PNG files are raster conversions. Check the linked file history and license terms before reuse; a source-metadata check is not certification of the artwork or a workplace installation.
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