Purpose
A Permit to Work (PTW) system is a formal, documented procedure that authorises specific people to carry out specific work in specific conditions within a defined timeframe. It ensures that high-risk activities are properly assessed, controlled, and monitored.
Activities Requiring a Permit
| Permit Type | Activities | Key Hazards |
|---|---|---|
| Hot Work Permit | Welding, cutting, grinding, brazing, soldering | Fire, burns, fumes, UV radiation |
| Electrical Permit | Work on live or isolated electrical systems | Electrocution, arc flash, burns |
| Confined Space Permit | Entry into tanks, ducts, pits, manholes | Asphyxiation, toxic gas, engulfment |
| Working at Height Permit | Work above 2m — ladders, scaffolds, roofs, MEWPs | Falls, falling objects |
| Excavation Permit | Digging, trenching, boring | Buried services, collapse, flooding |
| Roof Access Permit | Any work on or access to building roof | Falls, fragile surfaces, weather |
| Crane/Lifting Permit | Mobile crane, hoist, heavy lifting operations | Crush, drop, structural overload |
PTW Process
| Step | Action | Responsibility |
|---|---|---|
| 1. Request | Contractor/technician submits PTW request with scope, method statement, RAMS | Performing Authority |
| 2. Risk Assessment | Review hazards, controls, PPE, emergency plan. Site visit if needed. | Issuing Authority |
| 3. Issue Permit | Complete permit form. Both parties sign. Define valid period (max 24hr typically). | Issuing Authority |
| 4. Toolbox Talk | Briefing at worksite: scope, hazards, controls, emergency procedures. | Performing Authority |
| 5. Execute Work | Work within permit scope and conditions only. Permit displayed at worksite. | Performing Authority |
| 6. Monitor | Periodic checks that permit conditions are being maintained. | Issuing Authority / Safety |
| 7. Close Permit | Work complete, area safe, site restored. Both parties sign closure. | Both Authorities |
Hot Work — Specific Requirements
- Fire watch: Dedicated person with extinguisher during and for 60 minutes after hot work.
- Combustible clearance: Remove or cover all combustibles within 11m (35ft) radius.
- Sprinkler impairment: If sprinklers are impaired for hot work, notify fire alarm monitoring and insurance.
- Detector isolation: Specific detectors may be isolated (document which ones) — restore immediately after work.
- Hot work area: Non-combustible surfaces, fire blankets for protection of adjacent combustibles.
Confined Space — Specific Requirements
- Atmosphere testing: O₂ (19.5-23.5%), LEL (<10%), H₂S (<10ppm), CO (<25ppm) — test before entry and continuously during work.
- Rescue plan: Never enter to rescue without SCBA and rescue equipment. More people die in confined space rescue than in the original incident.
- Standby person: Dedicated person outside the confined space at all times — their sole job is to monitor and summon rescue.
- Communication: Continuous visual or voice communication between entrant and standby person.
References
- ISO 45001 — Occupational Health and Safety
- NFPA 51B — Fire Prevention During Hot Work
- OSHA — Confined Space Entry
- BNBC 2020 Part 7 — Construction Practices and Safety
Insights & Guidance
- 7 permit types: hot work, electrical, confined space, working at height, excavation, roof access, crane/lifting.
- Permits are time-limited (max 24hr typically), scope-specific, and require both issuing and performing authority signatures.
- Hot work requires fire watch for 60 minutes AFTER work completion — most hot work fires start after the welder leaves.
- Confined space: atmosphere test before entry, continuous monitoring, dedicated standby person, rescue plan without entry.
- No permit = no work. Permit conditions must be maintained throughout — any change requires permit re-issue.
Hot work, electrical work, confined space entry, and working at height are the activities that kill people in buildings. A permit to work system ensures these risks are assessed, controlled, and monitored every single time.
- Unpermitted hot work — leading cause of construction and maintenance fires.
- Confined space entry without testing — invisible gases cause rapid incapacitation.
- Expired permits — conditions may have changed since the permit was issued.
- PTW procedure document
- Completed permit forms (filed and retained)
- Risk assessments and method statements
- Training records for permit issuers and users
- Are contractors working with visible permits at the worksite?
- Is there a fire watch during/after hot work?
- Do confined space entries have standby persons?
- Do you have a formal permit to work system?
- Who is authorised to issue permits?
- How are permit conditions monitored during work?
- PTW system design — occupational safety consultant.
- Confined space assessment — industrial hygienist.
- Training — certified safety trainer (NEBOSH/IOSH).