Purpose
This SOP establishes the Lockout/Tagout (LOTO) procedure for controlling hazardous energy during electrical maintenance. LOTO prevents unexpected energisation of equipment that could cause electrocution, burns, or equipment damage. Electrical contact is one of the top causes of workplace fatalities in building maintenance.
Applicable Standards
- NFPA 70E — Standard for Electrical Safety in the Workplace
- IEC 60364 — Low Voltage Electrical Installations
- OSHA 29 CFR 1910.147 — Control of Hazardous Energy
- BNBC 2020 Part 8 — Electrical and Communication
When LOTO Is Required
- Any maintenance on electrical panels, switchgear, or distribution boards
- Replacing circuit breakers, contactors, or electrical components
- Working on motors, pumps, fans, or any electrically-driven equipment
- Any work where unexpected energisation could cause injury
- Cleaning or servicing equipment with electrical components
- Working on UPS systems, batteries, or generator connections
LOTO Procedure — Step by Step
| Step | Action | Responsibility | Critical Detail |
|---|---|---|---|
| 1 | Identify all energy sources | Authorised Person | Include stored energy (capacitors, UPS batteries). More than one source is common. |
| 2 | Notify affected persons | Authorised Person | Inform all occupants/workers who may be affected by the shutdown. |
| 3 | Shut down equipment normally | Authorised Person | Use normal operating controls. Do not just trip the breaker. |
| 4 | Isolate all energy sources | Authorised Person | Open breaker/switch. Physically verify the operating mechanism is in OFF position. |
| 5 | Apply lock and tag | Authorised Person | Each worker applies their OWN lock. Tag shows name, date, reason, expected completion. |
| 6 | Verify zero energy state | Authorised Person | Test with rated voltage tester. Test the tester on a known live source before and after. This is the most critical step. |
| 7 | Release stored energy | Authorised Person | Discharge capacitors, bleed pressure, block mechanical energy. |
| 8 | Perform work | Authorised Person | Work within scope. If scope changes, re-evaluate isolation. |
| 9 | Remove tools and verify | Authorised Person | All tools removed, guards replaced, area clear of personnel. |
| 10 | Remove lock and tag | Lock Owner ONLY | Only the person who applied the lock may remove it. No exceptions without formal procedure. |
| 11 | Re-energise and test | Authorised Person | Confirm all clear before re-energising. Test equipment operation. |
LOTO Equipment
| Item | Requirement | Standard |
|---|---|---|
| Padlocks | One per authorised person, individually keyed, durable, identified (name/photo) | Dedicated LOTO locks only — never use general-purpose locks |
| Tags | Durable, weather-resistant, show: name, date, contact, reason | Must withstand 22.7 kg (50 lb) pull force |
| Hasps | Multi-lock hasps for group lockout (accommodates multiple locks) | One hasp per isolation point |
| Voltage tester | Rated for the voltage being tested, properly maintained and calibrated | CAT III or CAT IV rated for panel work |
| Lockout devices | Circuit breaker lockouts, valve lockouts, plug lockouts as needed | Device must physically prevent operation |
Common LOTO Violations That Kill
- "Quick job, no need for lockout" — the most common last words. Every task on energised equipment needs LOTO.
- Using someone else's lock — only the person who applied the lock may remove it.
- Skipping verification — assuming isolation worked without testing with a voltage tester.
- Not identifying all energy sources — dual feeds, UPS backfeed, generator backfeed, capacitor stored energy.
- Tag-only without lock — tags can be removed by anyone. Physical lockout is required.
Arc Flash Awareness
Arc flash is an explosive release of energy from an electrical fault. Temperatures reach 20,000°C — four times the surface temperature of the sun. In buildings, arc flash risk exists at any panel rated ≥208V.
- Arc flash analysis — required for all panels to determine incident energy level and PPE category.
- Labels — arc flash hazard labels on every panel showing incident energy (cal/cm²), working distance, required PPE.
- PPE — arc-rated clothing and face shield per NFPA 70E for any work on or near energised panels.
References
Insights & Guidance
- LOTO is required for ANY maintenance on electrical equipment. "Quick jobs" without LOTO cause fatalities.
- 11-step procedure: identify sources → notify → shutdown → isolate → lock/tag → VERIFY zero energy → work → re-energise.
- Step 6 (verify zero energy) is the most critical — test with a rated voltage tester, and test the tester itself on a known live source.
- Only the person who applied the lock may remove it. No exceptions without formal management procedure.
- Arc flash risk exists at any panel ≥208V. Arc flash labels and PPE per NFPA 70E are required.
Electrical contact kills instantly. LOTO is the single most important safety procedure in building maintenance. Skipping it, shortcutting it, or assuming isolation worked without verification has killed experienced electricians worldwide.
- Unexpected energisation — equipment re-energised while worker is in contact.
- Arc flash — explosive energy release at panels, causing severe burns.
- Multiple energy sources — dual feeds, UPS backfeed, or generator backfeed not identified.
- LOTO procedure document
- LOTO equipment (locks, tags, hasps) available and maintained
- LOTO training records for all electrical workers
- Arc flash analysis and labels on panels
- Are LOTO locks and tags available at the electrical room?
- Are arc flash labels on electrical panels?
- Do technicians carry personal LOTO locks?
- Do you have a formal LOTO procedure?
- Are all electrical technicians LOTO-trained?
- Has an arc flash analysis been conducted?
- Arc flash analysis — electrical engineer with NFPA 70E qualification.
- LOTO programme setup — safety consultant with electrical safety experience.
- Training — certified NFPA 70E trainer.