Emergency Response - Methods of Release, Part 1 of 3
Dave Smith has been an Industrial Maintenance Electrician since 1975. He has taught maintenance, troubleshooting and safety courses to thousands of electricians in mines, mills, refineries, factories, plants, power stations and offshore platforms throughout North America and the Middle East. Dave is a hands-on guy and teache...
Both CSA Z462 [1] and NFPA70E [2] require workers to be trained in emergency procedures. Part of this requirement is that workers or employees "exposed to electrical hazards shall be trained in methods of release of victims from contact with exposed energized electrical conductors or circuit parts".
Even though the regular and continued use of voltage rated rubber gloves and leather covers is mandated in both standards, there will still be instances where mistakes are made, hazards not identified, procedures not followed, practices not practiced, etc. In these instances an electrical rescue may have to be effected.
In addition, both standards include the following as a requirement of a Qualified Worker: "The decision-making process necessary to determine the degree and extent of the hazard and the PPE and job planning necessary to perform the job safely".
It is therefore inherent that a rescuer must meet this requirement to conduct an electrical rescue. The plethora of look-alike electrical equipment in industry makes electrical rescue by a non-electrical worker a highly dangerous task.
The effect of electrical current on our body and various organs is well known. Three causes of immediate death can be current flow through the head, affecting the breathing center of the brain which controls the diaphragm muscle; current flow across the chest causing the diaphragm to constrict, leading to asphyxiation; or current flow through the chest causing the heart to go into ventricular fibrillation or cardiac arrest.
There must be a number of factors in place to receive an electrical shock.
The first must be contact with a source of electrical energy, which can only be caused by a breakdown or bypassing of the insulation system in an energized piece of equipment or part of a system; the second must be contact with another source of energy or ground; and then enough current to affect the person.
If you witness a person in contact with an electrical circuit, you may not even be aware that there's a problem. One of the author's clients had a welder standing beside a steel table that had an electrical outlet on it that had come in contact with the table. As the welder stood beside the table, he put his hand on it and went into muscular paralysis; the others with him did not realize it until someone noticed he was in physical stress.
At that point, they quickly discovered that the table was energized.
Most times it will be evident that the person is receiving an electrical shock. If the current is high enough, there will be such a violent muscular reaction that the body is propelled away from the contact because of the reaction of large muscle groups. Other times, though, a person will be hung up on a system. As current flows through muscle fibre, the fibres will contract. If someone's hand is on an object, current flow will cause the hand to contract making it difficult or impossible for the person to release their hands from the energized object. This natural phenomenon of the hand is the source of the old advice, "Always brush with the back of your hand".
Knowing precisely what to do in an electrical accident is important for both the rescuer and the victim. A common mistake people will make, and continue to make, is to think that a good swift body check is an effective way to release someone from a circuit. Depending on a tremendous variety of factors, it may or may not work.
When Lou Abel was a young roughneck his co-worker was rolling up a power cable and made the mistake of leaving it plugged in under wet and muddy conditions.
Lou's recollection: "He suddenly went completely rigid and a high pitch squeal came out of him!" Lou grabbed his shoulder to release him but was immediately thrown flat on his back. With the energy drained from him, Lou could not even lift himself off the ground, and as his co-worker continued the high pitched squeal, Lou clearly remembers wishing he would die soon so the screaming would stop. Before that occurred, another worker had the presence of mind to unplug the cable that the fellow had been rolling up.
After the fact it is perfectly clear that de-energizing is the correct response but in the stress of an accident you cannot imagine what an untrained response would be.
You must understand that the person's body is an extension of the electrical system and you have no idea what effect touching the person will have. Most workers are trained in hazardous gases and in confined spaces, and know that if someone is down and out in a confined space, regardless of their excitation level, that they must not affect a rescue because it's dangerous.
The same thinking must be learned about a person in contact with an electrical system.
Electric hand tool electrocutions are rare now-a-days but before the 1971 introduction of double insulated (DI), and recent development of battery operated (BO) tools, they caused many deaths. If a person was hanging on to a metal hand tool that became energized and were grounded with the other hand, it would be very difficult to rescue this person, as they would be tightly clamped to both the energized tool and the ground point. In this case swiftly unplugging the tool would be the correct response.
Companies assume their workers all use DI or BO tools but an audit will always discover angle grinders, saws-alls and other metal tools. Contract workers, especially welders, are a concern to be noted during tool audits.
It would be simple and inexpensive to have a tool and appliance tester set up at the tool crib and ensure that all metal cased electrical tools - drill presses, chop saws, etc, are insulation resistance (IR) tested at regular intervals. In 31 years, this author has only met one company that also set aside one day a year for workers to bring personal tools to the plant to be IR tested.
If you are an electrical worker, you want to make sure that everyone around you knows how to effectively rescue you. The author was teaching in a facility and a young student was pleased as punch because, a week earlier, he had saved an electrician hung up in a panel.
He said that even though he had "saved the electrician", the electrician was furious because, when he hit the electrician's arm with a 2 by 4, he broke his arm.
So if you're an electrical worker, and you don't want somebody applying a 2 by 4 piece of lumber to your body in your moment of need, you want to ensure that everyone around you understands clearly how to properly perform an electrical rescue.
When you are in a substation you should always know where the electricity is being fed from and where the main disconnects are. You should also know the various voltage systems; for instance an indoor substation could have 25kV, 15kV, 5kV, 600V, 480V and below. Most of these should be shown on a single line diagram that is required to be prominently posted in the station. If you do not know what is there, and where it is, you are not qualified to be in the station alone.
You should know how to disconnect each of these systems as well; these disconnect points will be identified on the single line but not their actual locations in the substation. You should always note where these are in case of an emergency.
If you're working in an electrical room with panels and MCC's, you should always know how to disconnect them. If you're working around a piece of machinery, you should know where the main disconnect for the machine is.
Astute companies will have main disconnects clearly identified so if an electrical rescue has to be performed any worker can quickly and immediately go to the source of power. They will also have electrical rescue hooks beside all panels.
Our electrical industry also needs to adopt concepts from the dangerous goods industry. In that industry there is a detailed list of every hazardous material and a specific placard for it. In the electrical industry we need to develop specific identifiers for every voltage level and placards to be put on every panel.
Enter into many indoor substations or electrical rooms and you will be faced with multiple sets of electrical grey look-alike cabinets with nothing apparent to distinguish one voltage level from the other. There will also be no indication of the main disconnect means other than a small plastic label.
This paper recommends that the voltage of every system be prominently identified in the top center of all accessible sides in 16" high letters and the main disconnect door be identified with fire engine red paint.
There are many ways that even experienced workers can find themselves in trouble. One of our senior instructors, Ed Rideout, relates a story in his classes, of an incident that happened when he was maintenance supervisor in a generating station. One of his electricians had de-energized, locked out and tagged a five KV motor starter. He had gone around to the back of the switchgear and was at the back of the cubicle. He had the door off when Ed arrived and said "You are in the wrong cubicle". His electrician said "No, this is number two pump" and Ed said "No it is number one. It is the seventh cubicle from the end and you have locked and tagged the eighth cubicle because I counted them". It turns out that at the last maintenance turnaround that the doors had been advertently mixed up. This is the reason to number the concrete in front of your cubicles and include in your procedures the necessity to check this.
If there's no way to disconnect (that you can see), you may have to remove the victim from the source of power. Depending on how tightly they're clenched to it will determine how easy it is for you. Every one of us carries insulators on us. At low voltage, a leather belt whipped around someone's arm can be used to pull them away. Your shirt can be used in the same way to pull someone away. Imagine right now if someone around you was hung up on a circuit what you could use to release them and remain safe yourself. The reason that fire crews practice regularly is so that when they encounter a fire, their practice has prepared them. You need to do the same mentally for electrical accidents. Firefighters can run into a thousand different situations; their training is general so it can be applied to all situations. Prepare yourself and your workers as well.
We know that in an electrical rescue, the person is going to have a difference of potential across their body. Most likely, their body is between one live source and ground and will you have to get them off the live source. An alternative may be to divert the current. If a person inadvertently has their hand stuck in a panel, the first natural reaction is to pull out, but if they push in and ground their hand and arm, the current flow may be diverted.
If someone was accidently connected to a remote piece of equipment because of an internal insulation fault and a failure of the ground system to function properly, then finding a way to short the cabinet to ground with something as simple as a pry bar or crowbar may divert the current to ground and reduce the voltage across the victim.
There are some situations where it's too risky to attempt a rescue, and in those unfortunate situations you will live with the trauma that every accident witness before you has also had to live with. Hopefully, by following some of these simple suggestions, if you see an electrical accident, and a victim needs to be released from a live electrical, then these suggestions may be of value.
Till next time, be ready, be careful, and be safe.
