I think my first experience working with 480 volts was at a Strammit plant.  A Strammit plant would cram straw under high pressure between two sheets of asbestos.  Though for awhile the product had popularity, it cannot be used today.  Probably there are few people who have ever heard of Strammit.

Another electrician and I were sent out to the Strammit plant.  I don’t believe either of us realized how dangerous 480 volts can be.  The location where we were to work on one of the circuits was across the building from the panel location.  We determined which circuit we were going to be working on and shut it off.

As we were working, we accidentally touched two wires together.  Doing so caused a huge, unexpected arc.  The other fellow went back to the panel and discovered that after we shut off the breaker to the circuit, someone had turned it back on.  Boy! Did he read those people the riot act!

We learned a valuable lesson that day.  If you are working on a circuit, control the environment by putting a padlock on the breaker in the off position, open up the panel board and disconnect the wiring to the circuit, or even hang a big sign on it.  Today that particular circumstance has all kinds of safety measures to adhere to.  I support all of them.

My last experience with high voltage was at the Spokane Airport where we were assigned to change the oil in two big transfer switches.  The two switches we were working on ran the whole airport.  For planned redundancy, the power at the airport came in from two different power sources.  If the power went down on one source it could be switched to the other, so that energy is always available.

Today, the oil used in those transfer switches has been outlawed because of environmental pollution.

I wonder how many of those transfer switches and transformers in the country, using that particular oil, have never had their oil replaced.