Q. I’ve been hearing a lot about arc flash protection lately, but I’m not sure if it applies to our operation and, if so, what the requirements are for providing personal protective equipment under this standard. I know it has something to do with our electrical power supply and equipment. Can you help clarify? S.V.
A. Due to the seriousness of shock and burn injuries associated with arc flash incidences from electric power, there has been a growing awareness and regulatory enforcement of facility electrical safety programs by the Occupational Safety and Health Administration (OSHA). OSHA’s electrical standard is 29 CFR 1910, Subpart S. In addition to the OSHA requirements, facilities should also be aware of the National Fire Protection Association’s electrical standard, NFPA 70E. Based on OSHA’s inspection history over the last several years, it is very likely the agency will use the NFPA 70E standard to determine whether or not you meet its electrical standard.
All attempts should be made to use lockout/tagout procedures and to never work on energized parts. However, there most likely will be situations in which a facility’s electrician will need to perform minor tasks on energized parts such as power panels, circuit breaker panels, motor control centers, disconnect boxes and equipment. One example of justification would be performing diagnostics or testing of electric circuits that can only be performed with equipment energized. In these circumstances, an electrical safety program is critical.
In accordance with NFPA, a proper electrical safety program includes provisions for:
The evaluation, documentation and determination of proper PPE necessary for “qualified” electrical staff when performing work on a piece of energized equipment can be achieved using the following four-step process:
Step 1 – Electrical Equipment Inventory
Start by conducting a plant survey and create an inventory of all the electrical equipment with voltages of 50V or greater. Note that the survey is not limited to panelboards, motor control centers and similar equipment. Items such as control panels on process equipment and anything else that may require energized work must be included. I recommend that you develop a spreadsheet that contains, at a minimum, the equipment location, a specific equipment ID, equipment type and voltage. This information will be needed to complete a hazard/risk category evaluation.
Step 2 – Determine Hazard/Risk Category
There are two approaches that may be taken to establish the hazard/risk category. One option is to have a detailed arc flash study conducted (NFPA 70E 130.3.A), including calculations performed by a qualified electrical engineer. These types of studies are very specific to your electrical equipment. A second option is to use the tables located in NFPA 70E. It is my experience that the tables in NFPA are more conservative, typically requiring significantly more PPE than a detailed study would. The cost in having engineering studies performed may lead some employers to rely more on the NFPA tables. If your facility wishes to have the more detailed engineering study performed, you could rely on the NFPA tables in the interim.
At the end of this evaluation, you should have identified the following:
In verifying that you have chosen the proper protective clothing, refer to Table 130.7(C)(11) (Protective Clothing Characteristics) for the definition of the minimum arc rating for the applicable hazard/risk category.
Step 4 – Electrical Equipment Inventory, Labeling and PPE
Now that you have evaluated and categorized all the electrical equipment at the facility with voltages of 50V or greater, finalize the initial inventory identified in Step 1 (Electrical Equipment Inventory) to include work description, hazard category and the required PPE. It may be somewhat challenging to complete the table in that there may be several job tasks (work descriptions) associated with each piece of electrical equipment that will require various PPE depending upon the hazard category ranking. If you do not manage to complete such an inventory, at a minimum have your “qualified” personnel understand how to use the NFPA tables prior to each job task requiring work on energized equipment.
Unless a power panel is for a piece of equipment is located on the equipment or next to it and obviously connected, labeling is required to clearly identify what it energizes. While not required by OSHA, a number of facilities label all their electrical equipment with voltage, hazard class, PPE and clearance distance.
By using the four-step approach outlined above, you will have evaluated and determined what PPE is needed for the qualified personnel to work safely at your facility. Remember to refer to OSHA and NFPA 70E electrical standards for additional information related to justification of work, energized electrical work permit, training and labeling.