On Aug 10, 8:40 am, Clark wrote:
wrote groups.com:





On Aug 9, 5:40 pm, "Hilton" wrote:
Hi,

Seems like it is a no-brainer (and easy) for pilots to use LEDs in
various forms. Why then, do miners not use them? Why do those trapped
miners only have a few hours of light available? Heck, the mine
companies could buy al cheapo LEDs for nothing and spread them
throughout the mine for little to no cost. These are give away items
now. One single tiny little LED would be invaluable right about now
and last forever.

Some things just don't make sense.

Hilton

Everything that goes into a mine has to pass the explosion proof test
requirements. LEDs can pass, but it has to be in a tested design.
That adds cost...

With low voltage systems it's fairly easy to meet the requirements for
hazardous area ops. IIRC anything below 5 volts is considered safe.

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It's not just voltage. The housing has to be able to contain an
explosion inside of it without igniting combustible gases in the
surrounding air...

Dean