Addendum to Safety at 600 volts [RE-wrenches]

[Phil Undercuffler, Positive Energy]

Sometimes, the greatest fear is the unknown.

In the fire training I mentioned in the earlier post, the aspect that really
caused concern was a power source that could not be disconnected--the high
round number just added to the alarm.  I just spent some time on the line
with John Berdner, who helped me fill in some of the blanks of what we might
expect in a failure mode.

Yes, systems are getting larger.  As systems have grown, we've moved from 12
to 24 volts, then on to 48v--each time, safety devices and methods used
before have become no longer listed or safe .  Suddenly, a company presents
a product that is a quantum leap, and it takes a little time to adjust--to
know how a system is going to work, and how it could fail.

I was caught thinking that because the voltage is 10x what I'm accustomed
to, the hazards must be linearly related.  From a property protection point
of view, John points out that at higher voltages/lower current, the energy
in an arc is smaller than lower voltage/high current--reducing wire heating
and insulation destruction.

Yes, becoming the current path on an array operating at 400+ volts can kill
you dead.  But so can the same on an array operating at a fraction of the
voltage, multiple of the current.  The lesson, of many learned, is
respecting both and ensuring that neither we or the public are exposed to
either.

For firefighters, I'll recommend horizontal ventilation whenever an array is
on the roof, and to focus their attention on whether there is a battery bank
involved--a truly scary scenario.

By the way, Doug, "handyman skills" was a direct quote from the guy on the
other end of the phone.  While I have fully rewired a Victorian home under a
homeowner permit in my years before solar and am extremely thankful for the
opportunity, I did not take the responsibility lightly.  I searched out
training far beyond what I would consider "handyman skills."

Thank you all for the patience

Enjoy the Sun!

Phil Undercuffler
Positive Energy

"The most beautiful experience we can have is the mysterious....
the fundamental emotion which stands at the cradle of true art
and true science"  --Albert Einstein

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