Christopher Coache

NFPA 70E Series: The burden of being protected from harm (Part I)

Blog Post created by Christopher Coache Employee on Oct 13, 2016

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Are you a craps player? You toss the dice and get a random outcome. Some outcomes have better odds of occurring than others. Sometimes it pays and sometimes you roll craps. Think of what you do at work. Are you rolling the dice to determine if you will be going home at the end of the day? Some of you consider the requirements in NFPA 70E® to be a burden especially if you are the one performing the energized work. NFPA 70E is intended to keep you reasonably safe from an electrical injury. The primary method which is to not have you exposed to electrical hazards in the first place. As the worker, think about what NFPA 70E requires of you.  It requires that you be able to perform a task on the equipment in a safe manner from the hazards you will be justifiably exposed to. I hope that working safely so that you can return home at the end of the day is not a burden.

 

What does NFPA 70E require for any scheduled electrical work? If you didn’t answer that the equipment be placed into an electrically safe work condition (ESWC) please look into what that means. There is no electrical hazard when equipment is in an ESWC. You will not be harmed by electrical energy. You can wear whatever you choose. Wouldn’t you be more comfortable wearing a t-shirt, shorts and flip-flops? (Note that this only applies to the electrical hazard.) Is it a burden to ask why the assigned task must be done while energized? Management’s or your own decision to have you perform energized electrical work is what burdens you to wear more gear. Is it a burden to find out why you are being put in harm’s way? If your employer is following federal regulations and NFPA 70E requirements there are only three justifiable reasons to expose you to risk of an electrical injury. These are greater hazard, greater risk and infeasibility. If revenue (in any form) is the improper justification for the energized work, your safety has been given a monetary value. I hope it is a high one since that will be your wager when the dice are thrown.

 

Assuming that energized electrical work is justified, what are the hazards that NFPA 70E is written to protect you from? Currently, it is to protect you from two hazards. The first is electric shock. During a shock, electrical current may travel hand to hand or hand to foot. Sometimes it is hand to head, chest, back or buttocks. When an electrical current is passing through your body you are rolling the dice. If it takes a critical path, hits at just the right cycle of the heartbeat sequence, lasts just a little too long, is on a high line circuit rather than low line, or enters through a cut in the skin that shock could become an electrocution. The level could also be high enough so that it just doesn’t matter what the conditions are or the path it takes. Electrocution is just a stone’s throw away rom an electrical shock. Electrocution has occurred at 120 volts. To my knowledge no one has ever survived an electrocution (check the definition). When you ignore NFPA 70E requirements for shock protection you are betting your life that you will only get a shock (this time).

 

Here are some generally accepted thresholds for a 60 Hz current passing through a 150 pound, healthy male:  Painful shock – 9 mA; Let-go threshold (start) – 16 mA; Impaired breathing and loss of muscle control – 23 mA; Possible ventricular fibrillation – 100 mA (3 second shock); Heart muscle failure – 500 mA, Burnt tissue and organs – 1500 mA.  The resistance of dry, undamaged, outer layer of skin ranges between 1,000-100,000 ohms. A typical human body model uses 500 ohms per limb and 100 ohms for the core.  Calculate the anticipated current levels at 120 volts. Are they higher than you thought? You probably perform energized work on 208 volt or higher systems. What do the numbers come to for your justified, energized work environment? The circuit current limiting device is most likely rated at least 20 amperes. Do you still want to gamble that you will not accidentally make contact?

 

My father was an old school electrician who was taught to test by touch and work bare-handed. One day he got “hung up”. Lucky for him, a co-worker realized that he had not moved for what seemed to be a long time. By my father’s account being helpless while feeling a painful, burning sensation made it seem like an eternity. He tells it that the co-worker could see it in his eyes that something was wrong. There was no other communication method for him. That co-worker most likely saved my father’s life. What would have happened if that co-worker did not notice? My father’s body could have stayed there until he went unconscious and fell away. He might have silently agonized until the electrical system opened the circuit for some other reason. He may not have survived. Almost every electrical worker knows someone who has rolled the dice and luckily only experienced a shock if they themselves did not. Several of you know someone who tossed the dice and lost. Hopefully, the next generation of electrical workers will not have the same experience.

 

So, the burden that you perceive to be put upon you by NFPA 70E are the requirements intended to save your life. You have to use tools anyway so why not use properly rated, undamaged, insulated tools? When you schedule the work you should know what is necessary to protect you from shock hazards for the specific task. You should not be modifying the energized electrical work permit in the field. It may be difficult to perform some tasks while wearing gloves so that must be one of your perceived burdens. Gloves are not the only method that can limit the risk of a shock injury but if they are necessary use them. The additional protection would not be necessary if the equipment were in an ESWC as primarily required. There should be no need to return to the truck to get the correct tool for a properly scheduled task but if that trip is necessary it should be taken rather than rolling the dice once again.

 

Next time: The burden of being protected (Part II).

Outcomes