Substations have their own distinct set of dangers. Personal experience and industry best practices, rules and codes have been used to compile the information on this page on substation safety. Some terrible catastrophes have occurred while working in substations and I hope these lessons will help prevent others from having to go through what I’ve been through.
An Introduction for Newbies
When I first entered a substation, one of the first things I thought was that anyone might be killed there very easily. At 6 feet 8 inches and able to reach 8 feet with my feet level on the ground, I was immediately taught how dangerous substations are, especially for me, a groundsman.
Workers at a factory where I worked in 1980 taught me an intriguing lesson about the dangers of being tall. The first time I arrived at a distribution substation job site, I climbed out of the van and stretched. A journeyman and two apprentices threw me to the ground and told me I needed to stop what I was doing. They didn’t value my services, but they were worried that I may take one of them with me if I blew up the place. In order to ensure that I would never again stretch or carry anything beyond my shoulders while working in a substation, they duct-taped my arms to my chest just above my elbows. The approach employed to make the point was rudimentary, and I strongly advise against its usage in the present day, yet it worked. It’s become a sort of ritual for me to never raise my hand above my shoulder when pointing anything out in a substation.
Put your hands in your pockets when you’re learning about energized substations. Because it’s an industry-standard practice, students who withdraw their hands from their pockets without alerting me will be expelled from class for the day. This is especially true at older distribution stations. Fortunately, changes to the National Electrical Safety Code (NESC) and substation construction requirements have helped lower risks over time.
Security for Employees
There are numerous reasons why it is a good industry practice to notify the dispatch centre or substation owner before approaching and exiting a substation. To begin, the dispatcher will let you know if a changeover is being made. So that you don’t end up bouncing off the fence because someone opened a 500-kV switch over your head or shut a circuit breaker you were inspecting, proper notice is essential. If an event occurs and you require medical attention, your dispatcher will already be aware of your whereabouts or at the very least know where to begin looking for you. Finally, the dispatcher will know not to re-energize the circuit until they verify that you are clear if someone goes into an electrified conductor.
As a refresher, hard helmets, safety glasses, and work shoes must be worn at all times inside a substation. In the event of an arc flash, flame-resistant gear should be worn.
Personnel should be warned of the potential dangers of erecting barricades. Hazardous places such as open control cable ditches or broken wire trough covers should be protected by barriers. On occasion, it may be a good idea to protect workers from high-voltage testing on substation equipment, depending on the risk to them.
Arrival and Departure
At all times, standard substation security should be observed. In order to enter and work in a substation, all of the gates must be closed and locked, depending on your company’s policy. All gates must be locked and closed while departing. The ground linking the gate to the fence must be in place after you’re inside. Also, before you touch any piece of equipment, make sure it is grounded properly. Stop and think about your options if the equipment isn’t grounded: either call in a professional to fix it, or, if you’re well-equipped and trained, install a temporary ground jumper and use correct live-line equipment to treat it like it’s activated at full primary voltage. Using a clamp-on amp meter, I’ve measured 8-12 amps on in-service grounds. Make sure to keep in mind that you are likely standing on a solid base of concrete and solid earth.
Substations are only accessible to skilled and authorized workers. Anyone who enters a substation on a temporary basis, like delivery people, must always be accompanied by a supervisor or crew leader. Three apprentices and I were nearly killed at a transmission substation many years ago. The driver of a flatbed truck belonging to a rental company walked into the substation without being escorted. When his truck’s exhaust stacks were so high, he came within inches of colliding with a 138-kV tap going down from a switch to a breaker while driving down the approved lane. I raced up to the truck driver and stopped him before he made an impact. Like the majority of the population, he had no knowledge about the dangers present in substations.
When driving a car through a power substation, precision is a must. It’s crucial to know where the roads are and whether or not you’re allowed to drive there. Obviously, drivers of high-profile vehicles must be mindful of high-voltage equipment even on signed highways. An observer should accompany high-profile vehicles in electrified regions. The location of raceways and cable/wire troughs where vehicles can cross is also important. It is important to avoid driving on any raceway or cable trough that is not clearly identified as a crossover location. Finally, avoid backing up your vehicle unless you have a spotter because everything in a substation is grey—grey gravel, grey fencing, grey columns, and grey structures. Instead, position your car such that you may exit it without having to back it up.
Guidelines for Occupational Health and Safety
Substations should also follow the following general safety procedures:
Mobile equipment, including aerial bucket trucks, excavating equipment, and cranes, should be grounded to the substation ground grid in compliance with specified norms and regulations. 4/0 stranded copper is the best option for this application.
The substation’s fenced-in facilities, including capacitor banks and reactors, are only accessible to qualified and authorized workers. Some people may not realize that these metal structures are energised.
• Be aware of the dangers posed by live and induced voltages. Make sure all equipment is turned off, tagged out, tested for voltage, and grounded if the situation requires it.
• Be careful around control room equipment, as some of it is quite sensitive to vibration.
Make sure you’re aware of the dangers of battery systems in the substation.
Equipment and materials should not be stored in a substation as a general rule. An untrained individual could get wounded if they are sent to remove the stuff. The substation’s stored equipment may potentially be damaged if any equipment in the substation malfunctions or blows up.
Inhalation and Exhalation Risks
Insects, reptiles, and animals are also potential hazards to keep an eye out for. As a result, the majority of today’s equipment is protected from animals and other species. Do not approach anything that is not covered in this material if an animal is present. Explosions can be caused by even the tiniest animals.
Wasps commonly construct enormous nests in steel structures within 15 feet of the ground in the southern United States. As long as you’re not allergic to wasp or bee stings, this is only an inconvenience. There are also numerous spiders, including as black widows and brown recluses, which can be found in control rooms, wire troughs, equipment cabinets and knobs. It is not uncommon for frogs to be non-lethal. When you open a circuit breaker or transformer cabinet at 4 a.m. and something cold, wet, and slimy falls over your fingers, it elicits an intriguing reaction in humans. Substations have long been plagued by reptiles, and I’ve personally had several close calls with snakes. Several years ago, I was awakened at 2 a.m. by a station alarm. After opening the door to a circuit breaker cabinet, I discovered a 4.5-foot-long rattlesnake slithering around within. I reacted instinctively and jumped back approximately ten feet, which convinced the snake to depart with a switch stick.
In the beginning of this post, I stated that I had sourced the information in this article from a variety of sources. Whether or not factual information is obtained from a reputable source is immaterial in the event that it saves a life. Keep yourself and others safe by sharing your knowledge.