Electrical Safety Procedures [PDF] in Plants and Refinery

This article is about General Electrical Safety Procedures which used in plants and refineries. We collected golden points for electrical engineers, technicians and managers based on industrial professional experience.

Electrical Safety Procedures

Electrical Engineers who are performing switching operations like operating the isolation mechanism, performing a physical break etc. must ensure following safety procedure in your mind and should apply on your team.

1. Safe Operating Procedures

Performing electrical operations, including switching, requires strict adherence to safety protocols to mitigate risks and ensure the well-being of personnel. Here are essential guidelines for these operations:

1. Personnel Training and Qualification:

All individuals conducting these operations must receive training and be qualified to operate the specific equipment involved.

2. Swift and Confident Actions:

All operations should be executed swiftly and decisively.

3. Vigilance for Unusual Indications:

Personnel should remain vigilant for any unusual smells or visual indications during and after the operations.

4. Caution with Unusual Incidents:

If an unusual smell, sight, or visual indication is observed, it should not be investigated during the operation. Personnel must promptly evacuate the area and report the incident to their supervisors.

5. Preparedness for Equipment Failure:

Operators must be prepared for the possibility of equipment failure during switching operations.

6. Safety Posture:

Whenever possible, personnel should position themselves to the side, extending their arms to limit exposure to the frontal areas of their face and body.

7. Restricted Access During Isolation Mechanism Operation:

Only individuals directly involved in operating the isolation mechanism of the switchgear are permitted in the area during this operation. All other personnel must vacate the switchgear room during this process.

8. Highest Risk During Isolation Mechanism Operation:

It’s crucial to recognize that the most significant risk of equipment failure occurs during the operation of the isolation mechanism of electrical equipment.

9. Troubleshooting Safety:

If personnel must be in the area for troubleshooting purposes, they should position themselves to the side of the equipment. Additionally, they must wear appropriate PPE as specified for their safety.

Adhering to these procedures is paramount to ensure the safety and effectiveness of electrical operations, particularly during switching activities.

2. Safety Interlocks

Equipment incorporates safety interlocks, such as door interlocks and shutters, to prevent accidental contact with energized components. Bypassing these interlocks is strictly prohibited, except in cases where the equipment is explicitly designed to allow access for maintenance or troubleshooting. Only Qualified Electrical Workers (Q-EL) are authorized to perform this activity. For instance, this applies to Motor Control Center (MCC) cubical door interlock access systems.

It is imperative to emphasize the following:

1. Equipment Must Not Be Forced:

Equipment should never be subjected to forceful actions, as this can compromise its integrity and safety features.

2. Avoid Unauthorized Extensions:

Unauthorized extensions or modifications must never be employed on any handle or operating mechanism, as these actions can defeat the purpose of safety interlocks.

3. Keyed Interlock Systems:

Keyed interlock systems should never be bypassed by removing locks. These systems are specifically designed to prevent incorrect switching sequences, and tampering with them may result in injury or equipment damage.

4. Disposal of Spare Keys:

Spare keys associated with keyed interlock systems should be properly disposed of after commissioning and before permanent power energization. This practice ensures that there are no unauthorized means of bypassing safety measures.

Maintaining the integrity of safety interlocks is paramount to safeguard personnel and equipment from potential hazards, and these guidelines should be strictly followed.

3. Access to Electrical Equipment Areas

Personnel in Electrical Equipment Areas:

Electrical equipment supplier representatives, power utility personnel, or electrical service personnel who need access to electrical buildings or rooms must wear the appropriate Personal Protective Equipment (PPE) detailed in Appendix A of this procedure. They should also be accompanied by authorized personnel.
Visitors, tours, or non-electrical personnel are strictly prohibited from entering these areas.

Exclusive Use of Electrical Rooms:

Electrical rooms or areas should only be utilized for operating or maintaining electrical equipment. Any non-electrical activities or equipment required in the same space should be separated by a solid wall to prevent direct access to the electrical equipment area.

Notification and Safety Work Permits:

Entry into switchyards and electrical rooms containing electrical equipment for maintenance purposes requires prior notification to site operations personnel and obtaining a Safety Work Permit for the intended work.

Door Safety Measures:

All doors in these areas must either have panic bars installed or be left fully open whenever someone is inside.

Securing Switchyard Doors:

Doors or gates in switchyards must be kept closed and locked when unattended.

Safe Distance from Overhead Power Conductors:

Maintain a minimum distance or radius of 5 meters (15 feet) for voltage levels up to 200kV, 6 meters (20 feet) for 201kV to 350kV, and 8 meters (25 feet) for 351kV to 500kV between personnel, equipment, vehicles, or structures and energized, unguarded overhead power conductors.
Vehicles in transit must also maintain minimum distances of 3 meters (10 feet) for voltage levels up to 200kV and 6 meters (20 feet) for voltage levels exceeding 200kV from energized unguarded overhead power conductors.
All work within substations or switchyards must adhere to these distances, and any restrictions should be documented on the Safety Work Permit. Repetitive tasks require documentation in a site-specific Job Safety Analysis (JSA) or Safe Work Instruction Manual (SWIM) previously approved by Qualified Electrical Workers (Q-EL).

Safety in Electrolytic Cell Lines:

When working near overhead/open low-voltage bus systems associated with electrolytic cell lines and rectifiers, personnel must exercise caution and wear appropriately rated Personal Protective Equipment (PPE).

Entry into Electrical Manholes or Cable Pits:

Personnel must not enter any electrical manhole or cable pit containing energized cables without prior approval from local site management and GSS Electrical Engineering.
If entry approval is granted and these spaces contain exposed energized parts, protective shields, barriers, or insulating materials should be used to prevent inadvertent contact with these components.
Pits are considered confined spaces and require confined space permits for entry, following the procedures outlined in 25-010533 for confined spaces.

Maintenance of Manholes and Cable Pits:

Regular inspections of manholes and cable pits should be conducted to check for the accumulation of oil and water.
In locations with high water tables or constant water presence, manholes and cable pits should be pumped out as needed for maintenance.
In areas with normal water conditions, pump out these spaces when necessary for maintenance activities or before the first yearly freeze.
Permanent pumps should be installed wherever practical, and caution must be exercised when using temporary or portable pumps to prevent cable insulation damage or contact with energized conductors.

Cable Handling:
- Walking or crawling on cables, whether located on cable trays or in cable pits, is strictly prohibited.
Safety Near Electrical Equipment:
- Personnel should avoid standing in front of or near terminal boxes on motors, heaters, transformers, and other electrical equipment.
Personal Protective Equipment (PPE) During Maintenance:
- During maintenance procedures, all personnel (including non-electrical personnel) within 3 meters or as defined by a specific arc flash boundary label of energized electrical equipment under maintenance must wear appropriately rated PPE.
- Temporary barriers or barrier tape may be used to keep personnel not directly involved with the activity outside the boundary.
- Personnel outside of the 3-meter boundary, or as defined by a specific arc flash boundary label, who are not wearing appropriately rated PPE, must not stand in direct line of sight to the maintenance and/or operating activities.

Strict adherence to these safety measures is crucial to ensure the well-being of personnel and the integrity of electrical equipment during access and maintenance activities.

4. Changes to Electrical Equipment at Existing Facilities

Compliance with Electrical Codes:

Any new additions to existing facilities must comply with all applicable local, state, and national electrical codes.

Review of Changes:

Any additions, removals, or modifications to existing facilities must undergo a thorough review process.

Verification of Circuit Capacity:

Before introducing new equipment to existing circuits, a competent individual must verify that the circuit or its components can accommodate the additional load without overloading.

Documentation of Changes:

All changes, including the introduction of new equipment, must be accurately documented on the most recent revision of electrical drawings (site master).

Adhering to these procedures ensures that changes to electrical equipment within existing facilities are carried out in compliance with regulatory standards and are well-documented for reference and future maintenance.

5. Electrical Jumpers and Bypasses

Adherence to Bypass Procedures:

All electrical jumpers or bypasses applied to electrical or other systems must strictly adhere to the safety procedures, known as the Bypass Policy.

Exemption for Permanently Installed Bypass Switches:

It’s important to note that permanently installed bypass switches that are associated with electrolytic cell line processes are exempt from the requirements specified in the Bypass Policy.

These guidelines emphasize the importance of following established bypass procedures and highlight an exemption for certain permanently installed bypass switches in specific contexts, such as electrolytic cell line processes.

6. Labeling of Electrical Areas and Equipment

Substation Yards and Transformer Areas:

All substation yards and transformer areas must display permanently attached signs with “High Voltage” labels on the fences. These signs should also indicate the highest voltage level present inside.

Arc Flash Labeling for Electrical Equipment:

Electrical equipment must be labeled for arc flash hazards in accordance with national standards and code requirements. Refer to the Engineering Guideline on Electrical Arc Flash Analysis for detailed guidance.

Labeling of Junction Boxes and Terminal Boxes:

Junction boxes, terminal boxes, pull boxes, transformer terminal chamber boxes, and similar removable cover-type boxes should be labeled with the highest voltage level they contain, as required by national codes and standards.

Switchgear Labeling:

Switchgear units must have labeling on both the front (breaker side) and rear (load termination side). The label should include the tag and/or unit number, equipment description, and voltage level.

Microwave Antenna Signs:

Microwave antennas, including dishes, poles, and masts, must have warning signs nearby to alert personnel to radiation hazards. These signs apply to telemetering, control, computer, and video communication systems using microwave technology (excluding land-line communication systems). The signs should convey a message such as “CAUTION – Radiation in this area may exceed hazard limitations, and special precautions may be required. De-energize or obtain specific instructions before working near or looking into the center of the antenna.”

High Voltage Motor Terminal Boxes:

High voltage motor terminal boxes must display a sign stating “Danger – Do not stand in front of cabinet.”

Electrical Room Notices:

All electrical rooms should be labeled with a sign reading “DANGER – Do not remain in switchgear room while High Voltage equipment is being started unless your job absolutely requires your presence.”

Authorized Personnel Only:

The doors to electrical rooms must be marked with a sign indicating “Authorized Personnel Only.”

High Voltage Substation Gates or Doors:

Gates or doors leading to high voltage substations should carry a caution sign indicating the potential presence of high magnetic fields and their potential impact on pacemakers or similar implanted cardiac devices. Signs may vary regionally and are not applicable to switchgear or electrical rooms unless specified by equipment warning labels.

Arc Flash Hazard Warning:
- All AC electrical equipment containing circuit breakers, switches, fuses, contactors, or isolating devices must display a sign warning of the presence of an arc flash hazard.
Electrolytic Cell Area Designation:
- Permanent signs should clearly designate electrolytic cell areas within the facility.
Cell Line Working Zone (CLWZ) Marking:
- The CLWZ, which encompasses exposed energized surfaces of the electrolytic cell line and its attachments, must be marked on the cell room floor with 4-inch-wide yellow striping (tape or paint). This boundary extends 42 inches horizontally from energized surfaces or structural elements, including aisles between cell lines. Signs indicating “Cell Line Work Zone – Authorized Personnel Only” should be stenciled at visible intervals. The plant layout drawing should be posted in each control room.
High Magnetic Fields Warning (If Applicable):
- If magnetic flux density testing reveals levels exceeding 10 Gauss, permanent signs warning of high magnetic fields and potential effects on implanted cardiac devices are required.

These labeling requirements are essential for safety and compliance, ensuring that personnel are aware of potential hazards and protective measures in various electrical areas and equipment.

7. Discharging Capacitors and HV Cables

7.1 Capacitor and HV Cable Discharge:

All capacitors within power systems, both High Voltage (HV) and Low Voltage (LV), as well as HV cables, must be safely discharged by a Fully Authorized person before commencing any work on electrical systems containing them. Temporary authorization for non-discharge may be granted by Electrical Engineering under specific circumstances.

7.2 Discharge After Diagnostic Testing:

Electrical equipment, including motor windings and cables, can become charged during diagnostic testing procedures. After performing such tests, it is imperative to ensure that the equipment is properly discharged to eliminate any residual voltage. Reference the associated test equipment and procedure for the correct discharging times, methods, and related instructions.

Properly discharging capacitors and HV cables is critical to prevent electrical accidents and hazards when working on electrical systems. These safety measures help safeguard personnel and equipment during maintenance and testing activities.

8. Changing Electrical Current-Carrying or Grounding Brushes

8.1 Safe Brush Replacement Procedures:

When dealing with electrical current-carrying or grounding brushes on rotating equipment, it is essential not to change these brushes while the equipment is in operation unless the brush holder assembly is explicitly designed to be replaced during operation. Such a system must have prior approval from Electrical Engineering, and a valid work permit must be issued to authorize this task.

8.2 Scheduled Brush Maintenance:

All brushes, commutators, and slip rings should undergo thorough inspection during scheduled equipment downtimes to ensure their proper functioning.

8.3 Off-Time Brush Replacement:

In cases where brush replacement is necessary and falls outside scheduled maintenance outages, the equipment must be securely shut down before initiating any brush replacement procedure.

8.4 Excitation System Ground Verification:

Prior to and after a downtime brush change-out, it is crucial to verify that the DC excitation system is not grounded. This precautionary measure helps ensure the safety and reliability of the equipment.

Observing these procedures for changing electrical brushes enhances safety and minimizes the risk of electrical accidents or equipment damage.

9. Anticipating Failure of Defective or “At Risk” Equipment

9.1 Managing Electric Equipment at Risk:

When there are clear indications that electric equipment is at risk of failing and potentially causing harm to employees, the equipment should be promptly deenergized. However, exceptions may apply when deenergizing the equipment introduces additional or heightened risks, or when it is not feasible due to equipment design or operational constraints.

9.2 Protecting Employees During Equipment Risks:

In cases where deenergizing the equipment is not immediately possible, or when it would create more hazards, employees must be safeguarded against potential risks associated with the impending equipment failure. This protection can be achieved through the use of barriers, barrier tape, warning signs, and other suitable preventive measures.

Prioritizing employee safety in the face of potentially failing equipment is paramount, and these procedures aim to mitigate risks effectively.

10. Reclosing Circuits after Protective Device Operation

10.1 Ensuring Safe Reenergization:

Following the deenergization of a circuit by a circuit protective device, the circuit must not be reenergized until a thorough assessment confirms that it is safe to do so. Reclosing circuit breakers repetitively or reenergizing circuits by replacing fuses or resetting protective relays is strictly prohibited. However, when it is evident from the circuit’s design and the operation of overcurrent devices that the automatic device operation resulted from an overload rather than a fault condition, a detailed examination of the circuit or connected equipment is not required before reenergization.

10.2 Specific High Voltage Switchgear Procedures:

For detailed guidelines regarding protective device operation on high voltage switchgear, please refer to EH&S Operation of High Voltage Switchgear.

These procedures emphasize the importance of ensuring safe reenergization after protective device operation, prioritizing the well-being of personnel and equipment.

Electrical Safety Procedures [PDF] in Plants and Refinery – 10 Rules