Driving to work one morning, deep in thought, pondering the many reasons companies use permanent electrical safety devices (PESDs) in their electrical safety programs, I nearly slammed into the back of a bus stopped at the railroad crossing. With a pounding heart and a rush of adrenaline, it hit me like a freight train: Both electrical energy and freight trains yield to no one. I finally stumbled across a perfect analogy for electrical safety principles.
During a blizzard on Dec. 1, 1938, a freight train named “The Flyin’ Ute” collided with a school bus driven by Farrold Silcox in Sandy, UT, killing 25 of the 39 students aboard the bus. In the 1920s, the use of “motor buses” (now just "buses") became commonplace. The public soon realized that a train colliding into a bus could be a disaster. To reduce this risk, laws governing vehicles at railroad crossings were passed; they have essentially remained unchanged today. Original laws required only bus drivers stop at railroad crossings. Over time, improvements were made that required bus drivers to also check their brakes when approaching a crossing, turn on their flashers, come to a complete stop 15 to 50 feet from the tracks, and look both ways before crossing the tracks. Sadly for the 25 students, Farrold Silcox had no idea that “The Flyin’ Ute” was bearing down on his bus at 60 mph – the train was largely unseen because of a howling blizzard and an unmarked rail crossing, and Farrold did not hear the train because of the bus’s closed windows and doors. Shortly after this tragedy, the laws changed in order to give bus drivers better visibility of an approaching train by requiring them to open the passenger door and driver-side window and wait at all rail crossings.
In many ways, this train story parallels the challenges of locking and tagging out unseen and unheard electrical energy because the latter task carries the same risk—instantaneous death. Isolating electrical energy in lockout/tagout (LOTO) is considered the riskiest task we perform daily. A bus stopping at the rail crossing is like the first step of a LOTO procedure: identification of the source and the opening of an isolator. Next, it must be verified that “no train is coming” – i.e., verify that there is zero voltage. Interestingly, the minimum OSHA compliance requirement for this task essentially involves having a qualified worker who is wearing personal protection equipment (PPE) carry and use a voltmeter – the mandatory 3-point voltmeter test. This is like a bus driver stopping at a rail crossing that is not outfitted with flashing lights and a gate. Installing Permanent Electrical Safety Devices (PESDs) into electrical equipment is akin to adding a gate and flashing lights at a rail crossing. This additional safety measure or secondary indication adds extra insurance that unseen and unheard electrical energy is identified before it potentially snatches lives. Opening the passenger door and the driver's window, checking both directions for a train is the final procedural step that bus drivers perform before crossing the tracks. Likewise, PESDs used in LOTO also need procedures that bring everything together.
With millions of school buses on the road today, one rarely hears of train-bus collisions like what happened years ago in Sandy, UT. Why? The safety examples discussed here have a common thread: Each requires multiple sequential failures occurring at the same time for an accident to happen. It is statistically improbable for a bus driver not to stop at the right place, a gate to malfunction, a warning light to fail, and the bus driver not to see an oncoming train.
For more than a decade, PESDs also have improved the safety record of thousands of companies that have deployed them in their electrical safety programs. For an accident to occur, there would have to be a failure of the isolator, a failure of the PESD device, and the a failure of the worker to correctly perform the mandatory voltmeter test. Most likely, each of these safety scenarios will evolve, but two things will never change – buses stopping at rail crossings and workers doing the mandatory voltmeter test, preferably in the presence of the energy verification provided by PESDs.