Entering Outdoor Substations, Part 6 of 8
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...
Once you’ve established there are no strange smells or sounds in your substation or electrical room, do a visual survey. Look for bulged equipment doors, things hanging from the ceiling, water infiltration, liquids on the floor, or anything else unusual. Look for the emergency lights, which are usually above the doors, and the location of the emergency equipment, such as First Aid kits and emergency blankets. Rescue hooks and fire extinguishers should be readily accessible.
(I believe every substation and electrical room should have a barrel of water with a quick-access top. Some might disagree, saying a substation is no place for water, and I’m not suggesting it should sprayed all over the place; I just know of too many instances where serious burns and amputations could have been reduced or prevented by quickly cooling the victim.)
When there are other workers in the substation, it may not be wise for you to be there. When they are in flash suits with equipment doors open, exit immediately. The flash protection boundary in most substations encompasses the entire substation when equipment doors are open, and the presence of flash suits indicates high incident energy—and you are at risk. When doors are open but the worker is only wearing a face shield and gloves, you are at reduced risk—but you have increased his risk because you are now a distraction.
When there is a fault in a substation, you have mere seconds to react—likely in the dark, with flames and toxic smoke boiling out of the equipment—so always know where the emergency equipment and exits are. Should you ever witness a co-worker caught in an explosion, you need to grab an extinguisher immediately. If the room goes dark, do not worry about calling for help, as people will already be running to see what happened. Get yourself as low as possible, because the smoke is toxic. First spray the equipment bottom-to-top, then your buddy (if he is in flames).
During fire extinguisher training, your instructor would have explained the difference between dry powder and CO2 extinguishers, and how to extinguish a co-worker on fire. It is impossible to miss your buddy’s face, so spray from shoulders to feet, and understand that he will be a moving target as he screams and writhes on the floor.
CO2 extinguishers are not recommended for clothing fires, as they are intensely cold at the trumpet, typically last for about 20 seconds, and hot materials will re-ignite. Always know which you have before you need to use them. When you only have CO2, then it is better to use it on your buddy than let him roast. With both, try to avoid his face and, again, understand your own subsequent trauma as you discover it is impossible—but you are doing as much as anyone could do.
A danger more common than arc flash is electrocution. Prepare for an electrical rescue before it happens by clearly knowing how to respond and under what conditions. Should some poor soul make contact at 2400V or higher, their muscular reaction is usually violent enough to expel them from the equipment. (Also note the presence of junk, as badly managed substations and electrical rooms are often used for storage, creating serious escape hazards.)
Locate the highest-voltage switchgear, which can easily be 2.4kV to 25kV, and the low-voltage switchgear. The law requires an accurate, up-to-date single-line drawing to be prominently displayed in the substation. Never forget which equipment is which. There have been numerous accidents where supposedly qualified workers have mistaken high-voltage switchgear for low—with tragic consequences.
The last safety course you attended probably did not have a final exam; a good instructor will inform you that your final exam starts the moment you leave the class and continues for the rest of your life. Remember that no matter how qualified or experienced you are, you are still capable of making a very stupid human mistake.
Until next time, be ready, be careful and be safe.©
