| quotient of the emergency luminous flux of the electric lamp supplied by the emergency ballast and the luminous flux of the same electric lamp operated with the appropriate reference ballast at its rated voltage and frequency Note 1 to entry: The emergency mode ballast lumen factor is the minimum of the values measured from the point of failure of the normal power supply continuously to the end of the rated time duration. Note 2 to entry: The emergency mode ballast lumen factor has unit one.
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