In 2012 I was washing down my Oshkosh Striker USAF P-23 ARFF truck after completing a morning operational check. These checks required us to drive the truck on about an eight to ten minute route on the flight line. The operational check includes testing the operations of the pump and roll, and all turret discharges for proper discharge pressure and pattern adjustment.
The truck was backed into the station and my back up man hooked up the air and plugged in the AC power into the back charging receptacle after I was parked and shut down. The truck was filled via the side 2 1/2″ fill via an 1 3/4″ line with an adapter. As it filled I washed down the dust and dirt from the “ops check” with the hose with no nozzle on the end. During that time, I had felt this strange, yet funny sensation in my hands while holding the hose. It was intermittent and really didn’t pay much attention to it since it was so brief. I finished rinsing the right side and switched to the driver’s side after disconnecting the 1 3/4″ fill line and putting it away.
I traveled from the front wheel wells to the rear wheel well I saw an area of mud that would not come off with the stream of water so I put down the hose and leaned in under the rear wheel well, placing my right hand firmly on the outside of the truck panel and under the top of the wheel well. I was going to rub the mud off with my left hand with the rag I had. My right hand was in a “L” shape right over one of the stainless steel bolts holding the paneling together as I leaned in, and when I did that I got a very nasty electrical “poke.” It felt like a tough kick to my arm and shoulder and down my leg.
Immediately I knew what that earlier sensation was on my wet hands and wet hose. I went to the back of the truck and unplugged the AC shore power to the truck and touched the truck again. No shock. The back of the truck was dry, and the cord was dry too. The puzzling thing was it was all hooked up to a power drop from the ceiling with a GFCI outlet.
I pulled out the rest of the pigtail extension cord from the GFCI outlet and immediately when to our Safety Chief’s office and told him. He came out to the truck and told me to plug it in. I advised him that I got a nasty poke and he doubted that could happen because GFCI’s are designed to trip on micro current. Well, he touched the aluminum ladder assembly and he got a nasty shock from that. He then confirmed that I wasn’t making this up, the hard way. I unplugged it, he touched it again and nothing happened.
The vehicle was then sent to our maintenance facility the next day (we kept it unplugged after that). They plugged it in (yes, a mechanic got shocked) and inspected the truck to fund out that the battery charger unit sat in a pan that had raised sides. Water had gotten into the tray and filled it allowing it to come in contact with the 120VAC feed terminals from the receptacle in the truck. This water in the pan led to the energizing of the whole truck, yet insulated from ground with the tires. The water fill hose had conducted some of that energy away traveling into my hose before it was disconnected, that is why I did not feel anything then. Once disconnected, the full current went through me.
The mechanics drilled a few holes in the tray so that water did not accumulate in the pan. That was the vehicle fix. It is unknown if this design flaw was ever made known to Oshkosh or outside our base.
The Safety Chief contacted out unit safety office who came in and inspected our GFCI outlets. 12 out of 14 ceiling drops failed to trip and were corroded. Also all 14 were the wrong type of outlet. Code required an outlet rated for outdoor use / moisture exposure and these outlets were interior design not designed for inside the apparatus bays. These outlets had no water resistant covers on them as well. This was a flaw never detected after the building was built in 2002.
Some design flaws may never come to light. When they do, and especially when it is energized electrical equipment, these need to be evaluated safely. Touching an energized device, vehicle, or piece of equipment once and getting a poke should be more than convincing enough to others not to do the same. We have volt meters, current detection sticks, and other devices to detect these things after an initial jolt. I am lucky I did not get seriously hurt, and others as well. These faulty devices must be treated with the lock out / tag out protocol.
GFCIs are not perfect. A small installation mistake like this inside a huge apparatus bay and a huge building project went unnoticed during initial approvals and inspections. These degraded over ten years and eventually failed. Personnel need to take note of their work areas, inspect and test out their GFCIs regularly, and make sure they are operational and up to code. No one wants a shocking experience like this.