3 Phase Power safety and information File uploaded

I have uploaded a file to the DYI-CNC, and Jobshophomeshop groups file
areas. Didn't see a way to upload it here, but most of you are on one of
these groups anyway. The file is called "3 phase power.PDF"

There has been a lot of discussion on 3 phase power on this and other list
over the last couple months. Some of the reply's were good, some not.

Some years back, when I was a Customer Engineer for IBM, and later as a
Service Planner, there were a number of accidents in customers accounts due
to miss-handling of three phase power, both by the customer, and by our
CE's. There was one fatality that I knew of. This was the result of a
power receptacle shell on a 240 three phase line being hot, and as the CE
grabbed the plug and receptacle to plug in a machine, he was
electrocuted. I personally have been knocked on my ass in a like situation.

As a result of these accidents, IBM put together a power safety course that
included all potential hazards in customer's environments, that every
person who might be in contact with primary power had to take once a
year. They made a handbook, "Electrical Safety for IBM Representatives".

I have taken information from this handbook and have put together a PDF
file called "3 Phase Power" that covers all of the types of 3 phase power
you might encounter in the U S. Some are also noted as being common in
Europe. This file includes phase measurements for no-fault conditions, and
also what to expect if a phase ground faults. This all assumes that the
house wiring is correct, which can be verified by the measurements. Always
make your first measurement from the power receptacle shell to ground
without touching the shell. EVEN if it has working equipment plugged into it.

I hope this file will answer the questions on 3 phase power and alert you
to some of the potential problems with it.

Don Rogers