Facility managers have reacted by trying to comply with standards that require Electrical Hazard Assessments and Arc-flash Hazard Analysis. Unfortunately, the standards can be confusing and misconceptions abound.

This article reviews the top five mistakes that facility managers who use in-house staff for assessments or who have hired some engineering firms have made and how to avoid them.

Mistake 1: Conducting an incomplete assessment. Many companies stop the assessment at the first 480V drop off the bus, because they wrongly assume there is no risk of Arc-flash below that point. This not only compromises worker safety, it is a violation of OSHA and NFPA 70E regulations that require all equipment to be assessed down to 50V for shock and Arc-flash hazards.

One example of this mistake is stopping the assessment at the main switchgear or a motor control center (MCC). The MCC may feed 277/480V power panels or a 480/120-240V transformer that in turn feeds an additional panel. Some motors fed from the MCC may also have a disconnect switch that must be assessed (and labeled per the 2008 edition of NEC 110.16).

Another frequent mistake is stopping the assessment at the first piece of equipment that achieves a Hazard Risk Category 0 rating. If the equipment supplies power to other equipment where workers may be exposed to energized parts, the other equipment must be assessed for arc-flash hazards as well. The severity of a potential arc-flash depends on the available fault current where the arcflash occurs and the opening time of the upstream over current protective devices.

Long cable runs or bus ducts can reduce the maximum available fault current, which increases the time it takes the upstream fuse or circuit breaker to open. This can escalate the incident energy possible at the equipment or panels downstream of the protective device and with it the Hazard Risk Categories and PPE requirements.

Never assume Hazard Risk Categories. Always confirm the possible incident energy at all equipment supplied from panels or equipment assessed at Hazard Risk Category 0.

Mistake 2: Using the NFPA 70E Table Method improperly. NFPA 70E provides a table for determining Hazard Risk Categories, but the Table’s footnotes state that it may be used only if the available fault current and the over current protective device clearing time are known to fall within certain limits. Many people overlook these footnotes, and use the Table Method as a short-cut without doing the required analysis. For example, for panelboards or switchboards operating at 240 or 480V, the available fault current cannot exceed 25kA and the clearing time of the overcurrent protective device cannot exceed two cycles or 0.03 second. These values must be calculated and verified in order to use the table.

Know the difference between IEEE 1584 and NFPA 70E calculations for arc-flash. Often it is wise to calculate using both methods.

Mistake 3: Trying to do an assessment with in-house staff. An electrical hazard assessment is a complex, labor-intensive endeavor. A typical company electrician may not have the required engineering background, experience or time needed to do the job. Many in-house efforts have to compete for resources and never get very far.

Hiring an outside engineering firm to do the assessment ensures that the job will get done, but not all outside engineering firms may be qualified. The assessment firm must show that it can gather data safely and provide a written protection plan. It must provide documented proof of its own workers’ safety training in equipment and tool usage, demonstrate that it uses NFPA 70E safe work practices and PPE, and that it will follow OSHA rules (including 29 CFR 1910.331 – Scope; 1910.332 – Training; 1910.333 - Selection and Use of Work Practices; 1910.334 - Use of Equipment and 1910.335 - Safeguards for Personnel Protection) while gathering data.

When evaluating vendor firms, the areas to consider include:

• Adequate resources;

• Specialized software;

• Experience at eliminating or reducing hazards;

• Ability to train workers and correct deficiencies;

• General business considerations such as experience, reputation, insurance coverage and a proven track record.

Mistake 4: Not correcting deficiencies after the assessment. OSHA provides severe penalties for failure to correct known deficiencies, not to mention the risk of liability. A 1999 EPRI study1 estimated the overall cost of an incident involving a death at anywhere from $3 million to $15.75 million. And even when a death does not occur there is still the cost of lost production and scrap caused by damage to equipment and possible plant shutdown.

Be sure to make all required equipment repairs and adjustments to correct improper interrupting capacity of protective devices and short-circuit current ratings of equipment. Implement all of the assessment firm’s suggestions to improve overcurrent coordination problems, as well as any other recommendations that could reduce or eliminate hazards or need for PPE and FR clothing.

It’s wise to upgrade to current limiting fuses or circuit breakers, which reduce the risk of arc-flash by limiting let-thru current and reduce incident energy during a fault.

It’s important to label equipment per NEC and NFPA standards. Both the NEC and NFPA 70E require equipment that may be worked on while energized to be field marked with arc-flash warning labels.

Mistake 5: Not changing work procedures after the assessment. OSHA 1910.132 and OSHA 1910 Subpart S require that managers identify electrical hazards and select proper PPE to protect their employees, train and qualify employees, and enforce safe work practices.

Workers must be informed about the potential hazards and the proper PPE for each task, and they must be trained in the knowledge of the equipment and tools necessary for maintenance and repair of equipment. NFPA 70E states that employees “shall be trained in and familiar with the specific maintenance procedures and tests required.” This training should be repeated annually.

The same engineering services firm hired to perform the Electrical Hazard Assessment of the facility will often be a good choice to do the employee safety training, as well as conduct continuing audits.

All electrical safety programs must include documented safety training and self-certification for qualified and unqualified employees. Training must be conducted by professional instructors (either in-house personnel or outside consultants), who can train employees on how to identify electrical hazards, how to assess and minimize hazards, and how to utilize specific safe work practices and procedures.

All test equipment as well as hand tools must be insulated and rated for the voltage of the circuits where they will be used. All tools and equipment used for maintenance must also be periodically inspected to ensure they are not damaged (i.e. torn insulation) and are still in good working condition.

According to NFPA 70E, Energized Work Permits must be used when work is performed on energized equipment. Oneline drawings must be updated when equipment moves or buildings are renovated.

Documenting all Safe Work Procedures is critical once all hazards are identified. Avoiding the five mistakes described here can go a long way towards ensuring worker safety and reducing the likelihood of lawsuits, regulatory penalties, and downtime caused by electrical hazards.

But none of this will mean anything unless management is fully committed to it, and does the necessary follow-through to make sure it happens. FSM

Larry Altmayer is a services manager for POWR-GARD, Littelfuse, Inc., and co-author of the Littelfuse Electrical Safety Handbook.