Safety Norms: Electrical Power Systems Engineering

1Purpose, Scope, and Safety Principles

These norms protect people who design, build, operate, test, maintain, and study electrical power systems. They also protect members of the public who live or work near overhead lines, substations, generators, and underground cable routes. The norms apply to classroom demonstrations, laboratory bench work, field measurements, protection testing, switching studies that use live operating data, and any hands-on activity on equipment connected to a supply.

Four principles govern all work. First, assume energy is present until a verified isolation proves otherwise. Second, no task starts without a written authorization that names the person, the equipment, and the scope. Third, hazards are controlled in order: elimination, substitution, engineering controls, administrative controls, and protective equipment last. Fourth, anyone may stop work when a hazard is not controlled, and no one is penalized for doing so.

2Roles, Competence, and Authorization

Accountability must be written down and assigned by name. The responsible engineer owns the design basis, study assumptions, and any change to ratings or settings. The authorized person in charge owns the work plan, issues and closes permits, and confirms isolation. Qualified persons perform energized or switching work they are trained and authorized to do. Students and trainees work only under direct supervision of a qualified instructor and within approved laboratory limits.

Competence means more than completing a course. A qualified person must understand equipment ratings, isolation points, approach boundaries used at the site, test instrument category ratings, and rescue and first aid arrangements. Authorization is specific to task and equipment class. It must be suspended after an incident, after a lapse in practice, or when a person changes role.

• Mandatory: confirm qualified person status in writing before assigning any task that involves exposed conductors or energized equipment.
• Mandatory: never allow a single person to perform high voltage switching, testing, or energized work without a second trained person able to summon help.
• Recommended: maintain a matrix showing who may perform which tasks on which voltage classes, and review it after staffing changes.

3Hazards and Risk Assessment

Hazards in power systems are severe and often invisible. The main categories are electric shock from contact with live parts or step and touch potential during a fault; arc flash, which releases heat, light, pressure, and molten metal; arc blast from equipment failure; falls from poles, towers, and elevated structures; struck-by and crush hazards from lifting, cranes, and moving machinery; stored energy in capacitors, batteries, springs, and pressurized gas or oil systems; fire from cable faults and transformer oil; and exposure to hazardous substances such as transformer oil, sulfur hexafluoride, battery electrolyte, and older equipment that may contain PCBs.

Risk is rated by combining likelihood and severity, then confirmed by a competent person. Use three levels for routine planning. Low risk tasks are de-energized, low energy work with verified isolation. Medium risk tasks involve nearby energized parts, test sets, or partial isolation. High risk tasks include any work within arc flash boundaries, any live work, any work near overhead lines, and any work where the isolation status is uncertain. High risk tasks require a written risk assessment, a permit, and senior review before work starts. Unknown conditions are treated as high risk.

Design and study errors are hazards too. Wrong protection settings, incorrect phase labeling, outdated single line diagrams, and incorrect clearance assumptions can create unsafe conditions long after the design is complete. Treat any mismatch between drawings and field conditions as a stop condition until it is resolved.

• Mandatory: arc flash incident energy and boundaries must come from a documented study by a qualified engineer using an approved method. Do not select protective clothing from a generic table alone.
• Mandatory: capacitor banks, cable ends, and large battery banks must be discharged and grounded before hands-on contact, using rated equipment.
• Recommended: maintain a site hazard register listing equipment, voltages, known faults, and special precautions for each location.
• Recommended: review hazards when drawings change, when new test equipment arrives, or when a near miss occurs.

4Preventive Controls and Safe Work Practices

Isolation is the foundation of electrical safety. Identify every source, including backfeeds from generators, customer generation, control power, and stored energy. Open the disconnecting device, lock and tag it under a lockout procedure, and verify absence of voltage with a rated and functionally tested meter. Test the meter on a known source before and after the verification. Apply grounding where the procedure requires it. Establish approach boundaries with barriers and signage before any hands-on work starts. Restoration follows the reverse sequence and is recorded on the permit.

Permits and switching orders convert the plan into a controlled process. A permit identifies the work location, equipment, hazards, controls, personnel, and the person who may release it. Work does not continue after the permit holder changes unless a new handover is recorded. Settings changes to protection relays follow a change control process: written request, simulation or bench test, peer review, scheduled implementation, and verification of the result before returning equipment to service.

Field work carries additional exposure. Keep vehicles, masts, ladders, and excavation equipment outside clearance distances from overhead lines. Protect members of the public by securing substations, fencing open trenches, and placing warning signs and barriers around energized equipment and cable works. Transformer and oil filled equipment work follows the manufacturer's instructions and site procedures; do not open pressurized or sealed compartments, and handle oil samples with gloves and eye protection. Never attempt rescue from a pole, tower, or energized structure without trained rescue arrangements already in place.

• Mandatory: live work on energized conductors or equipment requires written approval from the responsible engineer and the use of approved insulating equipment and procedures for the voltage class.
• Mandatory: keep prescribed clearances from overhead lines during ladder, crane, mast, drilling, and vehicle work. Obtain utility confirmation of line status and clearances before work begins.
• Mandatory: laboratory test circuits must be de-energized, with stored charge discharged, before any lead, jumper, or component is changed.
• Mandatory: use barriers and interlocks rather than relying on attention alone, and keep one hand free for measurements in energized low voltage or high voltage areas where practical.
• Mandatory: do not wear rings, watches, metallic jewelry, or conductive items near exposed conductors.
• Recommended: use a second person to check each lock, tag, and grounding connection before work begins.
• Recommended: standardize tool kits so every insulated tool carries a current voltage rating mark and a visible inspection record.

5Equipment, Protective Equipment, Environment, and Information

Personal protective equipment is the last line of defense, not a substitute for isolation. Arc rated clothing and face protection must match the documented incident energy and must be inspected before each use. Insulating gloves and sleeves must be tested and worn with leather protectors when required by the applicable standard, and any glove with damage, moisture, or unknown test history is removed from service. Hard hats, eye protection, hearing protection near transformers and switchgear, and fall protection suitable for the structure are required where the risk assessment calls for them. Verify current requirements with competent authorities and qualified professionals in your jurisdiction.

Environmental controls protect people and the surrounding area. Keep spill kits and absorbent material at transformers and oil handling areas, and report releases according to local environmental rules. Monitor sulfur hexafluoride handling and use leak detection in enclosed spaces where equipment is serviced. Battery rooms need ventilation designed for hydrogen release and no ignition sources. Use fire extinguishers rated for electrical fires and confirm access routes remain clear. Dispose of oil, batteries, and capacitors through approved waste channels and never pour them into drains.

Information is a safety asset. Single line diagrams, protection settings, and network models should be version controlled, and the current copy should be available at the work location. Restrict access to supervisory control and data acquisition systems and protection settings to authorized roles. Use unique accounts, change default passwords, separate engineering workstations from general internet use, and scan removable media before connection. Treat network diagrams, substation layouts, and customer data as sensitive, share them only on a need-to-know basis, and follow applicable privacy and critical infrastructure rules.

6Incidents, Emergencies, and Escalation

Immediate response starts with stopping the energy source safely. If a person contacts a live conductor, do not touch the person until the source is de-energized or the person is clear by means appropriate to the voltage. Call emergency services and the site emergency contact. Start first aid only if trained, and follow local first aid and emergency guidance. Emergency services provide professional medical care; this document does not provide medical instructions.

Treat any downed line as energized. Keep a safe distance as defined by the utility or local rules, keep others away, and call the utility emergency number. For arc flash, move affected persons from the area after the source is isolated, cool burns as trained, and preserve evidence such as damaged equipment and recorded data. For fires and oil releases, evacuate, call emergency services, and use suppression only if trained and safe. Escalate to the responsible engineer when a control fails, when a drawing does not match the field, or when equipment behaves unexpectedly. Escalate to management and regulators where local rules require it.

• Mandatory: report all injuries, electrical contacts, arc events, and near misses immediately, even when no harm is apparent.
• Mandatory: suspend the affected task and isolate the equipment until a competent person confirms it is safe.
• Recommended: conduct a root cause investigation within an agreed review period and share lessons learned with all affected teams.
• Recommended: rehearse rescue from energized structures and first aid response on a schedule set by the site.

7Records, Training, Inspection, and Review

Records prove what was done and enable learning. Keep permits, switching orders, lockout logs, test results, PPE inspection records, authorization records, incident reports, and change requests. Retain them according to local record keeping rules. Training records should show the topics covered, the assessment outcome, and refresher triggers, including when equipment, procedures, or roles change.

Inspection and testing verify controls. Inspect insulated tools and PPE before each use, verify test instruments against their calibration requirements, check grounding equipment condition, and review lockout devices for wear. Audit a sample of permits and isolations against the procedure, looking for gaps rather than blame. Use findings to correct procedures, drawings, and training.

Review closes the loop. Update the hazard register and these norms after incidents, significant equipment changes, new standards, or repeated audit findings. Compare near miss trends over time rather than relying on single events. Replace weak controls with stronger ones where feasible. Each revision should name an owner and be approved by the responsible engineer and the safety lead.

• Mandatory: keep permits and isolation records for every high risk task.
• Recommended: review this document whenever the site, equipment, or applicable rules change.

Implementation checklist

• Confirm qualified person status and task authorization before any work begins.
• Identify every energy source, including backfeeds and stored energy, and record them on the permit.
• Use lockout, tagging, and a tested meter to verify absence of voltage before hands-on work.
• Confirm arc flash boundaries and PPE from the current documented study before entry.
• Maintain required clearances from overhead lines and barriers around energized equipment.
• Inspect insulated tools, gloves, and PPE before each use and remove damaged items from service.
• Restrict access to settings and control systems, and use unique accounts with strong authentication.
• Report every near miss and unsafe condition immediately and stop work until it is controlled.
• Verify current laws, standards, and manufacturer instructions with competent authorities or qualified professionals.