1898 - Trouble in Utah
The Telluride Power Transmission Company built a 35-mile line from
Provo Canyon to the Mercur mining area. The line was put in service at
40kV, which was a world record. It was heralded as a great achievement:
“a happy and fitting consummation of the high-tension tests” performed
at Telluride CO. But trouble soon developed. The No.1 Provo insulator
was only 7 in. diameter and was not up to prolonged service at such a
high voltage. Interruptions to electrical power service ran as high as
14 per month. Within a year the mine at Mercur installed a steam engine
and discontinued the use of electrical power. All failures were due to
the line – some due to the insulators and some due to poor line
construction. Pins, crossarms and even entire poles would burn to the
ground during foggy weather. The affair was a devastating setback to the
power industry as a whole.
It did focus attention on the need to develop better
insulators for higher voltage service. Mercur was the first of many
high-visibility disasters caused by overconfidence in the insulator and
lack of respect for the demands of high voltage. The Journal of
Electricity called it "An inexcusable failure."
The Telluride Company’s response to the disaster was to boil the pins
in paraffin, treat the crossarms to exclude moisture and forbid the use
of metal anywhere in the construction except for the copper wires. The
all-wood approach worked until higher-voltage insulators were developed.
The Provo insulator itself was an excellent design when operated
within its limits. It was used at 22kV throughout the American west.