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The Dangers of Working Hot

The Dangers of Working Hot

An electrician dies after working on an energized 277V circuit. Find out why his employer wasn't held responsible. If you routinely grab exposed conductors barehanded by their insulation to install wire nuts, you're putting yourself at high risk for electrocution. If it's a 277V circuit, chances are you won't be able to let go. And without GFCI protection or someone present to administer CPR right

An electrician dies after working on an energized 277V circuit. Find out why his employer wasn't held responsible.

If you routinely grab exposed conductors barehanded by their insulation to install wire nuts, you're putting yourself at high risk for electrocution. If it's a 277V circuit, chances are you won't be able to let go. And without GFCI protection or someone present to administer CPR right away, you may end up dead. The following case demonstrates the dangers of working hot.

Dispatched from a construction labor supplier, an electrician worked several days for an electrical contractor. He was found dead, dangling from his ladder, after his foreman asked him to “safe-off” a 277V circuit and then left him alone. (The task of safing-off involves insulating and securing the exposed ends of hot or potentially hot conductors.)

After the accident, the victim's family sued the employer (electrical contractor) under the Serious and Willful (S&W) Misconduct exception to the workers compensation exemption that normally shields employers from big lawsuits. They claimed the electrician hadn't been properly instructed or equipped to work on energized wiring above 300V, as required by Cal-OSHA (California Code of Regulations Section 2320.2). The plaintiff alleged that 277V was part of a 480V system and confirmed OSHA's requirement that workers must use insulated gloves when working on energized circuits above 300V.

In addition to his contention that 277V presents additional danger not present in 120/208/240V circuits, the family's attorney tried to prove this seemingly “routine” procedure was, in fact, complicated and dangerous because the victim was: 1) on a ladder; 2) working above a “T-bar” ceiling with many exposed grounds; 3) working from the back side of the metal box; and 4) working in a low light/poor visibility area. Considering these facts, the plaintiff maintained that the supervising contractor should have been on-site to enforce the OSHA Energized Wiring Regulation and therefore was negligent.

The plaintiff's expert witness presented calculations to demonstrate why 277V circuits present extra danger. Human external body resistance is accepted to be around 10,000 ohms. At 120V, this allows a 12mA current to flow through the body. A 277V circuit allows a current of 27.7mA. The threshold of perception is about 1mA, and the inability to let go (the “lock-on” threshold) begins at about 15mA.

The plaintiff alleged that allowing the electrician to work hot under these circumstances (combined with the absence of lockout/tagout kits in the contractor's trucks) constituted S&W misconduct.

According to the presiding judge, to receive S&W benefits an applicant must prove: 1) the employer knew of a serious, dangerous work condition; 2) the employer knew the probable consequences of its conduct concerning the condition would cause a serious injury; 3) the employer acted with reckless disregard for its employee's safety; 4) the employer deliberately failed to take corrective action; and 5) the misconduct was the proximate cause of the employee's injury or death.

He further wrote: “An applicant cannot establish serious and willful misconduct by showing the employer acted with negligence, even gross negligence. Citing prior case decisions: The applicant must prove an exceptionally high degree of employer fault, surpassing even gross negligence… Serious and willful misconduct, within the meaning of Section 4553, is an act deliberately done for the express purpose of injuring another, or intentionally performed whether with knowledge that serious injury is a probable result or with a positive, active, wanton, reckless and absolute disregard of its possibly damaging consequences. In sum, the provisions … were designed to penalize intentional misconduct of an employer.”

After reviewing the evidence, the judge ruled against the plaintiff. “The dangers in the work the decedent was performing were open and obvious, and should not have needed explaining …The scope of the job was simple and the work techniques and hazards obvious to an experienced electrician,” he wrote. “Subsection (a)(3) [of Section 2320.2] did not require using insulated gloves when working below 300V.” He added, “It is worth emphasizing that at the time of decedent's accident, Cal-OSHA deemed it safe to work on exposed 277V energized electric systems without insulated gloves. Applicants suggest the failure to supply insulating blankets over the T-bar ceiling violated Subsection (a)(4). However, that subsection requires barriers to prevent contact with energized parts, not to prevent contact with grounding materials such as the T-bar ceiling.” Finally, an employer “could not be found guilty of Serious and Willful Misconduct for assigning an experienced, skilled journeyman to perform a potentially risky job that was part of a journeyman's normal duties.” Thus, he ordered the plaintiff “take nothing by reason of their claim.”

Although some of the judge's opinions might convince us that lawyers shouldn't be responsible for assuring safe electrical wiring practices, his decision was legitimate within the legal standards for this case. However, a consistent practice of working on energized 277V systems resulted in a contractor spending a lot of time and money in court. More importantly, it resulted in an unnecessary death.

What can we learn from this case? Technically, you “work a circuit hot” even when you merely connect an appliance. In other words, an electrician should always assume a circuit is energized — even if he knows otherwise. At one extreme, fully insulating yourself and making sure you have a solid footing may be overkill for “wire-nutting” two stripped 120V wires. At the other end of the spectrum, a wiring scenario such as the one presented in this case has all the tenets of a lethal situation and shouldn't be treated as routine, despite the ruling of this judge.

Any time you're on a ladder and above a T-bar ceiling, particularly working with live 277V, you should consider yourself in grave danger of imminent death. You shouldn't work alone in the event you should accidentally come in contact with the circuit. Although it's easy to become distracted while doing routine tasks, this case demonstrates the importance of taking the small amount of extra time it takes to watch over yourself and your coworkers, making sure to use “hot-circuit” safety practices at all times.

If your client balks at shutdowns, ask him if he's willing to be responsible for the death of an electrician. Then ask if he thinks the client's employees in this case were less disrupted by the death of a worker and the resultant presence of police, paramedics, and numerous investigators than they would have been by a brief disruption in production had the electrician performed the task with the power off.

Crawford is a forensic electrical engineer and electrical contractor living in Sandpoint, Idaho.

Sidebar:Electric Shock 101

One important factor that determines the severity of body damage from electric shock is the length of contact time a person has with an energized circuit. Contact time also affects the point at which fibrillation (erratic heartbeat) occurs.

Duration of contact and current path also greatly influence the effects of shock. Secondary factors include age, physical condition, and size of the victim. The lethal element of electric shock is current, although voltage, resistance, and frequency are also contributing parameters. The Table below lists the effects of AC current flowing through the trunk of a 150-lb adult male. (Current levels are approximate because of the many factors affecting the severity of the shock.)

AC 60 Hz

Perception level


No-let-go level


Fibrillation level (0.2 sec)


Fibrillation level (0.5 sec)


During electric shock, your arm muscles flex and become rigid, making it impossible for you to release your grip. The minimum amount of current causing this inability is the let-go current, which varies with frequency. Another important aspect of electric shock is the pathway a current takes through your body. This determines which tissues and organs suffer damage.

Source: “Working Hot: How to Avoid Disaster,” written by Jean-Pierre Wolff, Ph.D., Vice President, Electro-Test, Inc., May 1999.

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