This morning I was in a soon-to-be parking lot reparing some 2" pipes the
asphalt company's grader had mangled. The 2" sweeps were buried about 3 feet
deep so my coworker and I dug them up and were using a borrowed Rigid shop-vac to clean
out the mounds of fill dirt and concrete dust that had clogged the first few
feet of the pipe. To get past the bend of the sweep we duct-taped a three foot
length of 1" pvc to the end of the shop vac's hose, and then duct taped about 2" of 3/4"
smurf tube on the end of the 1" pvc and were poking it in like a giant
aardvark's snout down the sweep to get the dirt out. I was standing outside the
hole, and my co-worker was in the hole on his knees, hunched over the pipes
while the shop-vac did its work. Suddenly his shoulders jerked the way your
body jerks when you touch a live wire. I shut the shop-vac off and he told me he
just got shocked and saw a five inch electrical arc inside the sweep between the
wall of the sweep and the 1" pvc pipe stuck down it (it was about 7:45 am, broad
daylight). He said, "you take a
turn", so I got in the hole and continued on with the vacuuming. The shop vac
hose was hanging right next to my arm, and after about 5 seconds all the hair on
my arm started to stand on end. Shut the vac off, my hair lies down.. Turn it
on, hair stands right back up. I never got my shock or 5" arc, but thought it
was kind of interesting that a shop vac could build up that much static charge.
The weather wasn't particularly dry and the soil was damp. My guess is that the
dry cement powder filling the pipe might have helped things, but still, a first
for me.
