Can I use a multimeter to measure the watts used by a 220-volt electric dryer?

Question

Would like something like a 220v, functionally simpler, DIY version of the kill-a-watt. Working with folks running an electric dryer by venting it into the small room containing the dryer. Though the window is open, the door is closed. I am betting not venting to the outside is making the dryer use about 1/3 more electricity, or more! (I think this because the intake air is so humid.) But I'll need hard numbers to bring about change.

Please include references if possible.  

I know to respect 220v current...

helpful · Accepted Answer

Here is the only thing that I found in a reasonable price range. You would have to put it in a meter box and add male and female plugs to it. It really that is all I found for 220 V.

http://www.hialeahmeter.com/siphwame.html

ADDITIONAL
This is $17 plus shipping, scrounge a box off an tear down or something but they are not that much new. You will have it for the rest of your life. and it will do up to 200 amps and 120v too.

Graeme · Answer

Watts = volts x current (amps)

The cost of a amprobe that can give you the current reading of the electric dryer would be more expensive than a kill-a-watt meter.  The energy used at a given moment will not be affected by the humid air as the current drawn is related to the resistance of the wires.  (Ohms law)
What you could measure is how long the dryer runs when vented inside compared to running when vented outside.

I suspect that there will be no difference.

Yvonne · Answer

you can get a amp meter for your multimeter if you have a higher quality multimeter like a fluke most models have amp meter options. buy the amp meter at sears, auto parts stores. the price can vary from 100 bucks to 400 bucks for one. simply read the amps in each hot wire. then multiply amps and volts. the volts will be (220v in ur case but voltage does range it could be 210 volts - 240 each) what you get = the watts so 1 amp is 220 watts.  but you also must read both legs of the wires, one at a time with the amp meter on the cord. there's two hot wires and a neutral and a ground on a four wire cord; or two hot wires and a neutral on a three wire depends how old it is!

briggs451 · Answer

Recycling hot humid air will require more power because it will require longer dryer running time to achieve the same result. The electricity need to operate the machine will not change.

You don't need a power meter. If the dryer runs 30% longer on recycled air, it has used 30% more power. If you want to know the power needed to run the dryer,  look for the UL label somewhere on your machine, usually near where the power cord enters.  It will tell you the power consumption

Can I use a multimeter to measure the watts used by a 220-volt electric dryer?

4 Answers