Electric Cap lamps

       Different models of lamps used in the Bisbee mines

 In February of 1938 electric miner’s cap lamps were introduced underground in Bisbee.  This dramatic change in mine lighting first occurred in the Campbell and Junction divisions. Phelps Dodge provided the lamps to the miners , with a initial setup cost of $ 6,711.67.  The original miners cap lamp was approved in 1915 for use in underground mines.  Miners through the West resisted the change from carbide lamps to electric cap lamps, just like when  mines changed from candles to carbide’s. This is partly why they were introduced so late in Bisbee along with cost and poor battery technology in early lights.  
 

Edison Model K electric cap lamp

Edison Model K electric cap lamp

Edison Model K
      The first type of electric cap   lamp used in Bisbee was the Edison model K.  Made by the Storage Battery Division of Thomas A. Edison, Inc. the model K was approved to use underground by the U.S. Bureau of Mines 1931. The model K used a wet cell alkaline battery, sodium hydroxide was the electrolyte.  These lamps were notorious for leaking causing chemical burns on the legs of miners using them. There were incidents where a miner was buried by a cave in and the most severe injuries that the miner received was from the lamp. The leaking problem would continue with model P and R4 lamps made by Edison.   The lamps were made of stainless steel for the battery case and Bakelite for the lamp head. Charging was done through the battery. The battery top had to be removed with a special magnetic opener to expose the electrical contacts.
 

 Edison Model P cap lamp

 Edison Model P cap lamp

Edison Model P
   The Model P was approved for underground use in 1939 and again 1941 by the Bureau of Mines. The Model P would replace the Model K by the mid 1940’s in Bisbee. This model saw several improvements with a rigid battery case, smaller lamp head, better blub socket . The lamp’s major fault was the battery leaking a sodium hydroxide solution if tilted very far beyond vertical.    This dependable design would allow Edison to dominate the North America miner’s lamp market.  Most Bisbee mines would continue to use Model P until the 1960’s when they were replace by the Wheat Mark II.
 

edison R 4 miners cap lamp

 Edison R4  miner’s cap lamp

 Edison R4
   A few mines in Bisbee like the Cole saw the Model P replaced by the Edison R4. The R4 was approved for use in mine’s in 1949. It was first used in Bisbee in the 1950’s and it had limited usage. The battery had changed to plastic with stainless steel reinforcements . Charging was still done through battery and had to be opened with another type of special magnetic opener.  The lamp head size was increased and the bezel changed to a non-sparking metal. The battery design still leaked. This model only last a few years before it was phased out.
 

Wheat Mark II cap lamp

Wheat Mark II cap lamp

Wheat Mark II
     In the 1960’s the Mark II was ushered into Bisbee’s mines.  Made by the   Koehler Mfg. starting in the late 1950’s, this lamp would last until mining ceased in Bisbee. This type of lamp is commonly referred to as a ‘Wheat lamp” in the mining community. The battery was a lead acid type’ it would rarely leak and if it did only small amounts of acid would come out.  The charging was done through the head piece. This well design lamp is still made today and is often called a model 5100.  The bulbs have now changed from incandescent to halogen. Battery top went from being made of stainless steel to plastic in about 2000. In 2010 they stopped making the lead acid battery and switched to Lithium. 
 

Wheat Mark V lamp

Wheat Mark V lamp

Wheat Mark V

This lamp never saw actual service in mining operations at Bisbee. The Queen  Mine Tour used this type of lamp from its conception until 2012-early 2013 these lamps were stopped being  used due to a extremely high replacement cost of the new lithium batteries versions.

References
Approval and Certification Center Electric Cap lamps Approved under part 19 Pdf
C.E. Mills Notations from Annual Reports years 1909 through 1950July ,1958, p49 Phelps Dodge     Corporation
L.C.Isley, A.B. Hooker, W.H. Roadstrum, Investigations of Permissible Electric Mine lamps 1930-40., bulletin  441 pp 15-17 Bureau of Mines
J. Sammarco, J.Carr Mine Illumination: A Historical and Technological Perspective p.2
Richard Graeme IV 2012, pers. comm., 5 July
Richard Graeme III  2012, pers. comm., 2 July

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© 2013 by Doug Graeme