Measuring Ceiling Fan Power Usage

Rkg76

This may be a dumb question, but how would I go about measuring the power usage on a hardwired ceiling fan...measure it somehow at the electrical panel? My assumption is a Kil-a-watt meter is useless for this as there is nothing to plug-in?

Thanks
Russ

Cariboocoot

Re: Measuring Ceiling Fan Power Usage

Rkg76 wrote: »

This may be a dumb question, but how would I go about measuring the power usage on a hardwired ceiling fan...measure it somehow at the electrical panel? My assumption is a Kil-a-watt meter is useless for this as there is nothing to plug-in?

Thanks
Russ

You are correct: the K-A-W is useless unless you can get at the wiring to (just) the fan and put a plug and socket in. Otherwise if you know precisely what circuit it is on and can access the wiring for it you can use a clamp-on AC Ammeter to measure the power draw. That "access the wiring" is the difficult bit; often the only place you can get to it is inside the main panel box and that will be full of live wires when you run the test.

BB.

Re: Measuring Ceiling Fan Power Usage

Plus to "properly" measure power usage, you need access to both the circuit voltage and current (some sort of current tap/current transformer) to measure both the amplitude and the "phase" of the voltage and current...

Otherwise you can only measure the current and estimate:

VA = Voltage * Current (AC power measurements--As separate readings).

To actually measure power:

Power = Voltage * Current * cos (phase angle) = Voltage * Current * Power Factor (one meter, same time, volt+amp measurements).

That is what the KaW meter does--It measure both at the same time.

Somebody here made up an "outlet" where they could wire the KaW meter into their AC panel Branch Circuits--Can be done, but you have to know what you are doing or you could cause some real havoc.

-Bill