When to use a permit-to-work system

A PTW is appropriate for work such as:

• Hot work. Cutting, welding, brazing, soldering and anything that uses a naked flame. Drilling and grinding should also be included where a flammable atmosphere is present.
• Work on non-live electrical systems. An electrical permit to work is mainly a statement that a circuit or item of equipment is safe to work on: it has been isolated and, where appropriate, earthed. Never issue an electrical permit for work on live equipment or to authorise live working. The permit should state clearly which equipment has been made dead and the points of isolation, and the lockout/tagout (LOTO) system should be followed.
• Machinery maintenance. Maintenance adds risk because safety-critical systems are disabled and guards removed to reach dangerous parts. The permit system makes sure the power source is fully isolated, stored energy is released and LOTO is followed.
• Confined spaces. Under HSE guidance, an enclosed or largely enclosed place is a confined space when specified serious risks are reasonably foreseeable. Avoid entry where reasonably practicable. If entry is necessary, an assessed safe system must verify isolation, atmospheric precautions, communication and suitable rescue arrangements before work starts. A permit may coordinate these precautions but cannot make an unsafe atmosphere or engulfment risk safe.
• Work at height. A permit may be appropriate where assessment identifies a need for formal coordination. First avoid height, then prevent falls, prioritising collective protection, and minimise remaining distance and consequences. A harness alone is not an effective fall-arrest system; suitable anchorage, clearance, compatibility and prompt rescue are essential.
• Other high-risk activities, as the organisation decides.

Summary notes for Element 3 · Cheat sheet · Glossary. A study aid, not published or endorsed by NEBOSH.