Pinpoint Electrical Problems & Hazards When Working On Infrastructure
By Mitch Frazier
By shutting off power, arc flash and shock hazards are eliminated when working on electrical systems. For safety reasons, OSHA states that work should not be performed on live panels.
In some facilities, however – including higher-education institutions – taking the electrical system offline may not be possible (or at least not very desirable). Colleges and universities often prefer to stay up and running instead of shutting down an entire building to complete necessary electrical work.
In cases like these, qualified electricians are requested to work on energized systems. To do this safely, it’s important to:
- Understand potential hazards including arc-flash risks.
- Take preventive measures to reduce them when possible.
- Understand the types of personal protective equipment (PPE) that should be worn for protection in case of an arc flash event.
Arc Flash Assessments: Meet OSHA Requirements & Reduce Liability
OSHA currently requires arc flash assessments to be completed or updated when a building’s electrical infrastructure is being replaced, upgraded, or newly installed and if an assessment was not completed when the system was installed. Many older college and university facilities weren’t designed to with today’s modern electrical systems and components; an arc flash assessment can help to pinpoint potential problems and hazards before work begins.
These assessments not only ensure a safer working environment, but they also help you select the appropriate level of PPE that workers should use while working on or near the electrical system for sufficient protection.
Arc flash assessments can also help reduce your institution’s liability if an arc-flash incident occurs (or if OSHA conducts an onsite inspection). In these cases, OSHA may ask to see arc-flash assessment results, including arc-flash risk calculations, correct PPE recommendations, and expect to see proper equipment warning labels installed.
Significant penalties may apply if those results can’t be provided. For example, the fine for a panel that is not correctly labeled can be up to $13,260 per panel.
What is an Arc Flash?
An arc flash is a spontaneous electrical explosion that reaches an extremely high temperature; it occurs when electrical contacts are bridged with a conducting object on an energized system. A release of electrical energy occurs between the two components, causing an explosion. This could result from improper installation, equipment failure, exposure to moisture, a dropped tool, or even dust or corrosion build-up.
Arc flashes can cause equipment damage, unexpected downtime and data loss, and even severe injury or fatalities if people are working on or near the electrical system.
The Six Steps of an Arc-Flash Assessment
Conducting an arc flash assessment can help determine the likelihood and potential size of an electrical explosion in a given situation based on:
- Size of electrical service
- The age, type, and condition of electrical components
- The surrounding environment
Each piece of equipment is categorized based on incident energy (released thermal energy) and the arc flash protection boundary (a boundary indicating where a worker would be exposed to a second-degree burn in an arc flash). This process follows a series of six steps.
The first step in an arc flash assessment is gathering information about your building’s electrical system and utility data for the system feeding it (operating voltage, available fault current, etc.), information about each panel, protective device, equipment loads and conductor specifics area all obtained. Qualified electricians will assess each of your system’s panels by opening the covers, determining conductor sizes, and gathering information about breaker settings and types.
The second step in an arc flash assessment is making sure that electrical system design documents are up to date. Especially in older buildings, you may not know what your electrical system encompasses if information wasn’t appropriately recorded and documented throughout the years. If the documents are outdated or no longer correct, they should be updated accordingly.
An electrical system model is developed (or updated, if it already exists) using the updated one-lines and the information gathered on the electrical equipment configuration from the main breaker(s) or fuses on down to each panel and to large motors.
The model is then used to determine the maximum available fault and the coordination of protective devices at each piece of equipment. The maximum available fault level is compared to the rating of the device to confirm that the equipment is designed to handle the fault if one were to occur. Also the protective device settings are compared to confirm the devices are coordinated to ensure the correct device operates in the event of a fault.
Incident energy is determined from the arc flash model to indicate the amount of energy that would develop in an arc flash if one were to occur at that location. Having this information helps determine proper PPE. In addition, it can identify locations where the arc flash rating (or calories per square centimeter, which is how arc flashes are measured) is higher than 40. In these cases, the electrical equipment is deemed dangerous and must be de-energized before work is performed. PPE won’t offer adequate protection from an electrical explosion at this level.
After calculations are complete, the findings are presented, along with an explanation of the implications and potential changes that may need to be made. Arc flash warning labels are then created and applied to electrical equipment as required per NFPA 70E. The labels convey the arc flash assessment results, including PPE requirements, arc-flash distances, and incident energy potential.
Getting Ready for an Arc-Flash Assessment
If your higher-education institution has an electrical project in the works – or you want to better understand how your electrical system looks and functions – following these steps can ensure you’re your workers and equipment will be protected, even when work is being done on live systems.
Use the Most Current IEEE Standards for your Arc Flash Assessments
New 2018 version of Institute of Electrical and Electronics Engineers (IEEE) standards are now being used to base arc flash hazard calculations. IEEE 1584 has remained mostly unchanged since its original publication in 2002, with two minor amendments in 2004 and 2011. Make sure the consultant your working with is utilizing these new calculations (IEEE 1584-2018) for your arc flash assessment! Learn more about these updates:
- Updated IEEE Guide for Performing Arc Flash Hazard Calculations (IEEE 1584-2018)
- IEEE 1584-2018 produced in collaboration with the National Fire Protection Association (NFPA) to better protect employees and contractors in the working environment.
- After analyzing more than 1800 tests, the IEEE 1584 working group constructed a new arc flash model that is significantly more accurate, though equally more complex than those in its predecessor.