basic electric theory #4

Thread Starter


Joined Oct 30, 2011
Please help with this question.You are an electrician installing the wiring in a new home.The homeower desires that a cealing fan with light kits be intalled in five rooms.Each fan contains a light kit that can accommodate four 60 watt lamps.Each fan motor draws a current of 1.8 amperes when operated on high speed.It is assumed that each fan can operate morethan thre hours at the time and,therefore,must be considered a continuous duty device.The fans are to be connected to a 15 ampere circuit.Since the devices arecontinuous duty,the circuit current must be limited to 80% of the continuous connected load.How many fans can be connected to a single 15 ampere circut?How many circuit will required to supply power to all five fans? PLEASE TELL ME HOW YOU GOT THE ANSWER SO THAT I CAN DO THIS PROBLEM!


Joined Nov 25, 2009
It depends on where you are from. European-style power supply networks run on 220V whereas US-style ones run on 110V.

You already know the fan current draw, you now need to know the lamp draw to find the fan kit current need.
Each lamp will have a standard current draw, specified by the formula I=P/V, where I is the current draw, P is its power rating.

Find each lamp's current and then the whole kit's current. Once you know that, you can find how many fan kits can fit in the 80% capacity of a 15A fuse.