No Protection

The device offers no designed-in protective features. Exposure to the hazard cannot be avoided through skill or technique; it can only be minimised through PPE.

Examples

• –Manual spray painting without ventilation. The operator will inhale fumes during use, regardless of technique.
• –Welding without a screen. The operator will be exposed to UV radiation during use, regardless of technique.

Safe Only With Correct Use

The device offers no designed-in protective features, but the hazard can be avoided entirely through correct skill and technique.

Examples

• –A basic chainsaw. Safety depends entirely on operator technique, stance, and PPE (chaps, helmet, gloves).
• –A tube-style belay device. The device has no automatic braking. Safety depends entirely on the belayer maintaining proper grip and technique.
• –A knife. No guards or safety features, but proper technique makes it safe to use.

Safety Encouraged

The device has designed-in cues, markings or warnings to encourage correct behaviour, but does not block unsafe use.

Examples

• –An extension ladder with angle indicators, "this side up" labels, and anti-slip feet. These cues guide correct setup, but nothing prevents the operator from ignoring them.
• –A medication bottle with a warning label and dosage instructions. The guidance is clear, but nothing prevents the user from ignoring it.
• –Electrical wiring with colour-coded insulation. The colours guide correct connections, but nothing prevents crossing wires.

Safety Assisted

The device has designed-in features that prevent errors or reduce harm automatically; for example, parts that only fit one way, or mechanisms that cushion consequences. However, misuse is still possible during normal operation.

Examples

• –A power drill with electronic brake, torque limiter, and insulated casing. These features reduce injury risk, but the operator can still slip or drill into something they shouldn't.
• –A car with seatbelts and airbags. The safety systems help significantly in a crash, but reckless driving can still cause serious harm.
• –An assisted-braking belay device, whether passive or active. The device helps catch a fall automatically, but incorrect technique can still cause the rope to slip through.
• –A child car seat with ISOFIX connectors. The seat can only click into the correct anchor points, but the harness straps can still be adjusted too loosely.
• –A gas cylinder regulator with a reverse thread fitting. The connector physically won't attach to the wrong gas type, but once connected the operator can still open the valve too fast or use incorrect pressure.

Fail-Safe

The device has designed-in mechanisms that enforce a safe state the operator cannot override during normal operation. Edge cases or external hazards may still exist, but the device's primary hazard is fully controlled.

Examples

• –A microwave oven with redundant door interlocks. The magnetron physically cannot energise unless all switches confirm the door is sealed. The operator cannot run the microwave with the door open.
• –A lift with door interlocks and slack-rope brakes. The car cannot move unless the doors are closed, and it will stop automatically if the cable fails.
• –A climbing gym auto-belay. The device automatically takes up slack and arrests falls mechanically. The climber cannot override the braking system during normal use.
• –A lawnmower with a two-hand operator presence control. The blade only runs while both hands grip the handles, so the operator cannot reach into the blade area during normal use.

Inherently Safe

The hazard has been designed out entirely. The device simply cannot cause serious harm through normal use.

Examples

• –A plastic letter opener instead of a metal blade. It can open envelopes but cannot cut skin.
• –Safety scissors with rounded tips. They can cut paper but cannot cut skin.