Welcome
Controlling high-risk engineering work
Welcome to Lesson 06 of Component 12. Today you will explore how engineers use safe systems of work to control activities that cannot be made safe by simple instructions alone.
The lesson focuses on permit to work and lock out, tag out (LOTO), both widely used when machinery, stored energy, electricity or hazardous work creates serious risk.
How do we make sure dangerous equipment cannot be restarted while somebody is still working on it?
Learning Outcomes
What should you know by the end?
Prior Knowledge Check
Quick recap before the main learning
Why This Matters
Maintenance work can expose hidden hazards
Servicing, repairing or inspecting machinery may expose workers to electricity, pressure, gravity, rotating parts, hydraulic systems, pneumatic systems or other stored energy.
A normal operating control such as a stop button is not always enough. Safe systems are used to make sure the work is planned, authorised, isolated and communicated properly.
A maintenance engineer is inside a guarded machine enclosure. What could happen if another worker restores power without knowing?
Main Learning Content
Safe systems, permits and isolation
Safe System of Work
A safe system of work is a formal method for carrying out a task safely. It sets out the hazards, precautions, responsibilities, sequence of work, equipment required and emergency arrangements.
Permit to Work
A permit to work is a formal written or electronic authorisation used for specified high-risk activities. It confirms that required precautions have been completed before work starts.
Lock Out, Tag Out (LOTO)
LOTO is used to isolate hazardous energy and prevent equipment from being energised or started while maintenance or other work is taking place.
- Identify all energy sources.
- Shut down the equipment safely.
- Isolate the energy source.
- Apply a personal lock and warning tag.
- Release or restrain stored energy.
- Verify that isolation is effective.
- Complete the work safely.
- Remove locks only through the authorised procedure and restore the system safely.
Never assume that “off” means “safe”. Isolation must be verified before work begins.
Lesson Presentation
Teacher-led learning • PowerPoint 6
Safe Systems
Use PowerPoint 6 for the teacher-led explanation of safe systems of work, permit-to-work procedures and lock out, tag out.
▶ Open Lesson PresentationYour Lesson 06 PowerPoint or PDF will be connected here when it is uploaded.
Engineering Case Study
Unexpected machine restart
Maintenance Scenario
A technician isolates a conveyor using the normal stop control and begins removing a jam. Another operator sees the conveyor stopped, assumes it is available and attempts to restart it.
Discuss
- Why is the stop control alone not a safe isolation?
- What energy sources should be identified?
- Where should locks and tags be applied?
- Who should be responsible for removing the lock?
- How should isolation be verified?
Explain the sequence of control. Do not simply write “use LOTO”; describe how it prevents unexpected energisation.
Class Activity
Design a safe system of work
Permit-to-Work Scenario
Contractors need to carry out welding close to stored combustible materials in an engineering facility.
Check examiner-style mark guidance
Indicative marking points:
- Identifies fire/explosion risk from hot work.
- Recognises nearby combustible materials as a hazard.
- States that work should be formally authorised.
- Includes removal/protection of combustible materials.
- Includes suitable fire prevention/fire-fighting arrangements.
- Explains communication, supervision and cancellation/close-out of the permit.
Higher-level response: link each control to the specific hazard and explain why formal authorisation is necessary.
Lesson Summary
Key safe-system principles
Safe System
A structured method for completing work safely and consistently.
Permit to Work
Formal authorisation for specified high-risk work.
LOTO
Isolation, locking and tagging prevents unexpected energisation.
Verify
Isolation must be checked before maintenance or intervention begins.
Exit Ticket
Show what you can now explain
Check answer guidance
Q1: A planned and documented method for completing a task safely, including hazards, controls and responsibilities.
Q2: Examples include hot work, confined spaces, electrical work, work at height or maintenance on hazardous plant.
Q3: LOTO isolates hazardous energy, secures the isolation with a lock, warns others with a tag and requires verification before work starts.
Complete Worksheet 9: Safe Systems.
Worksheet 9
Safe Systems • Component 12 Practice
Worksheet 9: Safe Systems
Complete the worksheet to practise safe systems of work, permit-to-work requirements and lock out, tag out procedures.
Worksheet Resource
Make sure you can explain when a permit to work is needed, describe LOTO and justify why isolation must be verified.
AI Lesson Companion
Future VITHAAA learning support
Ask VITHAAA AI
Students will eventually be able to ask questions about safe systems, permits to work, LOTO and engineering isolation procedures here.