How do you find the source of static electricity?
Here's the situation:
Our forklift operators can open and close an elevator door by using a pendant control that hangs near the elevator (so they don't have to get off of the lift). Frequently, but not always, the operator will get zapped by electricity as he grabs the control. We have also seen a spark when the pendant control bumps the roll cage as the forklift is driven up to the elevator (before the operator grabs it). It seems to be static electricity because there is just one zap (I suppose it could also be a capacitor discharging?)
Details:
The elevator is big enough to lift/lower 2 forklifts (side by side) with loads. It has one hydraulic cylinder and only goes up/down 1 floor.
Both elevator doors (upstairs & downstairs) have controls on a wall panel and controls hanging from the ceiling on a pendant (just like crane/hoist controls). The upstairs pendant is covered with plastic and rubber with no exposed metal parts. The downstairs pendant is covered with metal. Both pendants will zap a forklift operator.
The forklifts are propane powered, have solid rubber wheels, and ground straps that drag on the floor (some are rubberlike, some are metal chain, some wirelike). Our plant is clean with epoxy covered concrete floors.
The operators say they only get zapped at the elevator (pendants and wall panel controls) and not at other pendants like roll up doors.
I'm trying to figure out what the source is: The epoxy floor, the forklift, faulty controls, hydraulics, etc.
What meters are available to measure static charges?
After I find the source, I should be able to fix this.
Thanks for your help.
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