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. We need to develop specific identifiers in the electrical industry for every voltage level, and put placards 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 another. There will also be no indication of the main disconnect means other than a small plastic label.
I recommend the voltage of every system be prominently identified in the top centre 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 class 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 5kV motor starter. He had gone around to the back of the switchgear and was at the back of the cubicle.
The electrician had the door off when Ed arrived and said, “You are in the wrong cubicle”. His electrician said, “No, this is Number 2 pump,” and Ed said, “No it is Number 1. It is the 7th cubicle from the end, and you have locked and tagged the 8th cubicle… I counted them”.
As it turned out, the doors had been inadvertently mixed up during the last maintenance turnaround. This is why you number the concrete in front of your cubicles, and include the necessity to check them in your procedures.
When there is no apparent way to disconnect, you may have to remove the victim from the source of power; the ease with which you will be able to do this depends on how tightly the victim is clinging to it. 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 that someone around you was hung up on a circuit: what could you use to release them while remaining safe yourself?
The reason that fire crews practice regularly is so that, when they encounter a fire, their practice has prepared them and actions become automatic. 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 victim is going to have a difference of potential across his body. Most likely, his body is between one live source and ground, and you will have to get them off the live source. An alternative may be to divert the current. When a person inadvertently has his hand stuck in a panel, the first natural reaction is to pull out, but were they to push in and ground their hand and arm, the current flow may be diverted.
Were someone accidentally 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 also some situations where it is too risky to attempt a rescue and, in those unfortunate situations, you will live with the trauma that every accident witness also has to live with. Hopefully, when you see an electrical accident and a victim needs to be released, following some of these suggestions may be of value.
Until next time, be ready, be careful and be safe.