By Jack Smith
While attending an arc flash seminar several years ago, I had the pleasure of meeting Rich Kragh, P.E. of Kragh Engineering Inc. Kragh is a consulting engineer who specializes in forensic investigations after incidents that involves electricity. I recently had a conversation with Kragh and asked him some questions relating to arc flash.
When Kragh gets involved it’s usually because there has been an injury or fatality. Although the majority of cases Kragh has investigated are not related to arc flash, he said that around 5 percent of his cases are.
Kragh works in the Midwest primarily. He has not seen a lot of evidence of companies having arc flash hazard analysis performed at their facilities. He said he has not seen labeling on equipment that would indicate results of an analysis. The labeling describes the amount of energy likely at specific arc flash boundaries and the appropriate level of personal protective equipment (PPE) at that specific location.
Kragh suggests that too many companies are still not having the analysis done. “I don’t think a lot of people recognize just how serious the situation could be,” Kragh said. “I’m still hearing, ‘We’ve done it this way for the last 30 years and we didn’t get hurt, so we’ll keep doing it this way.”
According to Kragh, some insurance companies are not insisting that an arc flash hazard analysis be performed, and electrical inspectors are not enforcing it. “Before it’s acceptable to go online, equipment should be checked out,” said Kragh. “It should be part of the installation process to have the analysis done and have the equipment marked. It’s what the NFPA-70E requires.”
The High Cost of Saving Money
Companies are either unfamiliar with the NFPA-70E requirements for a hazard analysis, or they lack the resources to do the analysis, according to Kragh. “To do it right, you almost have to have a computer program where you can plug everything in and let it do the calculations to give you fault currents at different points,” Kragh said. “Larger companies tend to have the analysis done because they can afford it.
“Smaller companies probably have a higher risk factor because some of them have fewer well-trained employees,” Kragh continued. “Many small companies figure they can’t afford to do the hazard analysis. They fail to realize what a death or a serious injury could cost them.”
Kragh said that one of the main reasons that arc flash incidents continue to occur is the failure to de-energize equipment before working on it. “That seems to be pretty common,” he said. “If you work on equipment energized, the full available fault current of the system is available. Then, if you make a mistake, you’re pretty much dead.”
Another preventable cause of arc flash incidents is the use of test equipment that is not suitable for the task at hand, according to Kragh. He said there have been arc flash occurrences where workers did not have test equipment with the proper category rating. Typically, an arc inside the test equipment—or even the test equipment exploding—can be enough to start the arc flash process. Once the arc plasma begins, that’s enough to sustain the arc until an upstream device clears the fault. “You have to have test equipment that’s suitable for the available voltage and current levels,” Kragh said.
Kragh also emphasized the importance of PPE. Those who get hurt the worst are typically the ones who are not wearing PPE, or are not wearing sufficient PPE.
Companies that make electrical protection devices have continued to improve their products. Breakers are available with quicker trip times. Some of them have quick trip maintenance modes and adjustable trip times that support selective coordination. Some are available with network communications that enable “smart breakers” to send signals to upstream or downstream devices to coordinate zone selectivity. Current limiting fuses are available as well.
These electrical protection devices are designed to reduce the I²t, which minimizes let-through energy and shortens the flash boundaries. “They minimize the damage and reduce the potential of injury,” said Kragh. “But they won’t eliminate the arc flash.”
An Ounce of Prevention…
Regardless of the size of the company or its budget, taking steps to prevent arc flash incidents is of primary importance. “They have to realize the seriousness of not having the [arc flash prevention] program,” Kragh said.
Kragh offers several recommendations. “I would say for them to get educated on NFPA-70E, which is the standard for what needs to be done. They also need to have energized work permits. And they have to be enforced.”
Kragh also suggests that companies work with their insurance company. Asking if the insurance company has a proactive arc flash hazard prevention program is a good place to start. Some insurance companies are requiring higher degrees of compliance with NFPA-70E. Companies that are non-compliant could face increased premiums or cancelled policies. Some offer discounts on premiums for compliance. “If they get a break on their insurance, they might take the steps to do the right thing,” Kragh said. “They may be able to offset the cost of the analysis.”
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