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The energy efficiency of various kinds of photocontrols can be hotly debated.
However, the real story is in maintenance costs. The data in the histogram
below are taken from unaudited surveys received from more than 300 utilities
in 1992-1993. As you can see, the average cost is $29.04. Since then,
as deregulation gathered steam, utilities have done more analysis of their
maintenance costs. Now figures from $42.50 to $100 per maintenance call
are reported, depending on type of service territory; e.g., congested
cities with short mileage between trouble spots may take longer to service
than distant points in a rural area.
For a system of 20,000 lights, the difference between a 10% failure rate
and a 1% failure rate is 1,800 trouble tickets. At $29.04 per maintenance
call, this additional labor would cost $52,000 annually. For a system
of 150,000 streetlights, the difference between a 10% failure rate and
a 1% failure rate would be $392,000.

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