Permissible Electric Cap Lamps and Ventilation in Certain California Mines and Water-Tunnel Construction Page: 1
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PERMISSIBLE ELECTRIC CAP LAMPS AND VENTILATION IN
CERTAIN CALIFORNIA MINES AND WATER-TUNNEL CON-
STRUCTION'
By S. H. As 2 AND J. H. RANKIN
INTRODUCTION
HAZARD OF OPEN LIGHTS IN GASSY MINING OPERATIONS
Records of mine disasters and fatal accidents that have occurred
in mines of all kinds in the United States show that the majority of
deaths that resulted from explosions and fires before the adoption of
electric cap lamps were due to the use of open lights. Explosions
resulted when open-flame lights were used in mines or tunnels that
liberated explosive gas and in blasting operations when black
powder, fuse, detonators, or other explosive material was handled in
the presence of open lights. Fires are also caused by open lights and
the use of smoker's articles in all types of mining.
The use of open lights underground is always dangerous; and in
many instances no change was made, although they were considered
dangerous, often because a suitable lighting medium was lacking.
Flame safety lamps did not afford adequate illumination, and the
handicaps they presented for general mine lighting prompted the
use of open lights or mixed lights to be continued in many dangerous
situations. With the introduction of permissible cap lamps,4 coal-
mining people in large part have recognized their advantages, not
only in safety, but also in greater efficiency.
Because explosive gas is usually absent from metal mines and tun-
nels, persons engaged in these branches of the mining industry have
so far failed to recognize the economic advantages to be gained by
the more general use of up-to-date permissible electric cap lamps.
The reasons given are that these lamps are not necessary, that
they are believed to be costly, and that they offer handicaps to
workmen. In spite of the fact that thousands of permissible electric
cap lamps are in use in coal mines (a reliable estimate places the
figure at 350,000 for mines of the United States) many of our coal-
mining people continue to use open lights not only in so-called open-
light mines but also in some mines officially designated gassy, as well
as in blasting operations which require the use of black powder, fuse,
and detonators, or squibs.
SWork on manuscript completed January, 1932.
2 District engineer, U. S. Bureau of Mines Safety Station, Berkeley, Calif.
a Superintendent and senior civil engineering inspector, water department, city of San
Francisco, Calif.
l Usley, L. C., and Hooker, A. B., Permissible Electric Cap Lamps: Bull. 332, Bureau of
Mines, 1930, 39 pp.
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Ash, S. H. (Simon Harry), b. 1889 & Rankin, J. H. Permissible Electric Cap Lamps and Ventilation in Certain California Mines and Water-Tunnel Construction, report, 1932; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc12528/m1/3/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.