It is not feasible to develop a single set of hazard controls for energized work that covers every electrical task. The nature and complexity of these controls is dependent upon the combination of the Hazard Class (voltage and power levels) and the Hazard Mode (risk level) of the energized electrical task to be performed. In general, electrical work at LBNL can be organized into eight hazard classifications, according to the degree of energy present, and three hazard modes, according to the operational status of the equipment or system.
There are 7 procedural steps that must be completed before any energized electrical work is performed:
Step |
Description |
1 |
Justify that the task cannot be accomplished in a verified deenergized condition. |
2 |
Determine the Hazard Class. |
3 |
Determine whether you are Qualified and Authorized to perform the task identified in Step 2. |
4 |
Determine the Hazard Mode. |
5 |
Determine the requirements for hazard control. |
6 |
Obtain Energized Electrical Work Approval. |
7 |
Implement hazard control requirements and perform the task per the approval procedure. |
Hazard Classes
The Hazard Class is a function of the potential exposure presented by the voltage, current, power and stored power or energy available while performing the task. Because premises wiring usually presents extremely high fault currents, a separate category is used for Facilities equipment. Experimental or R&D equipment is a second hazard category. Finally, batteries appear in a third hazard category. The four Facilities category Hazard Classes are1A, 2A, 3A, & 4A, and the four R&D Hazard category Classes are 1B, 2B, 3B, & 4B.
These three categories and their associated Hazard Classes are characterized in the following charts:
R&D Energized Hazard Classes
Note: Voltage is line-to-ground or line-to-line, whichever is higher.
Facilities Hazard Classes
Note: Voltage is line-to-ground or line-to-line, whichever is higher.
Battery Hazard Control Requirements
Working on battery installations have further OSHA and NFPA requirements. Contact EH&S for help.
This chart does not release the worker from understanding and following these requirements.
Hazard Modes
The Hazard Mode is determined by what work procedure will be performed. The three task hazard Modes, in order of increasing danger, are:
- Working on or near Deenergized circuits or components. In this mode all operations are conducted in a verified deenergized state. All external sources of electrical energy are disconnected or controlled by some positive action (for example, with a locked and tagged out circuit breaker), and all internal energy sources are rendered safe. See PUB-3000 Chapter 18, Lockout/Tagout.
- Performing Energized Diagnostic and Test procedures on circuits or components. This mode
includes measurements and observation of equipment functions, without
manipulation, which are conducted with the equipment energized and with
some or all protective barriers removed and interlocks bypassed. Some
examples are:
- LOTO verification
- Troubleshooting or diagnostics.
- Normal expected operation of premises wiring connected isolation devices, such as bank switching, rolling out breakers, and disconnecting a load via a switch.
3. Working on energized exposed components.