# NCEES 123, Power



## allafra (Feb 8, 2011)

I am confuse, they are asking for the luminous flux (I), but the answer they give is for ilumninace (L). Can some one clarify or they just made an error?


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## papa j (Feb 9, 2011)

allafra said:


> I am confuse, they are asking for the luminous flux (I), but the answer they give is for ilumninace (L). Can some one clarify or they just made an error?


My understanding is that Luminous Flux (measured in Lumens) is the total perceived light emitted from, in this case, a lamp.

Illuminance is total luminous flux on a surface. The Unit is lumens per unit area (Square meter or square foot).

Hope that helps.

IIRC (Don't have test in front of me) You would multiply the design Foot-Candle by the area then divide by the Coefficient of Utilization.


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## allafra (Feb 10, 2011)

Thanks, that helps


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