DIY Home Improvement Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
I'm trying to measure the current required by my refrigerator. I bought a 10 watt 0.1 ohm resistor and spliced it into one of the wires (not the ground wire) in a short 14 ga. extension cable to the refrigerator. I'm guessing that the refrig requires about 8 amps, so the voltage cross the 0.1 resistor should be about 1 volt. But when I try to measure it, my voltmeter doesn't register anything (and the refrigerator is indeed powered by the extension cord). What am I doing wrong? Or is there a better way to meaure the current (besides buying an expensive AC current measure gauge)?
 

·
Licensed electrician
Joined
·
13,380 Posts
The refrigerator data plate will have the information on it. Look near a door for a sticker.
 

·
Licensed Electrical Cont.
Joined
·
7,829 Posts
I'm trying to measure the current required by my refrigerator. I bought a 10 watt 0.1 ohm resistor and spliced it into one of the wires (not the ground wire) in a short 14 ga. extension cable to the refrigerator. I'm guessing that the refrig requires about 8 amps, so the voltage cross the 0.1 resistor should be about 1 volt. But when I try to measure it, my voltmeter doesn't register anything (and the refrigerator is indeed powered by the extension cord). What am I doing wrong?
You are thinking like an engineer, that's what.
You need to start thinking like a normal person. :whistling2:



Or is there a better way to meaure the current (besides buying an expensive AC current measure gauge)?
Yeah, a $20 Kill-A-Watt like in the link.
http://www.amazon.com/P3-International-P4400-Electricity-Monitor/dp/B00009MDBU
 
  • Like
Reactions: jbfan

·
Master Electrician
Joined
·
1,165 Posts
tfox37380 said:
I'm trying to measure the current required by my refrigerator. I bought a 10 watt 0.1 ohm resistor and spliced it into one of the wires (not the ground wire) in a short 14 ga. extension cable to the refrigerator. I'm guessing that the refrig requires about 8 amps, so the voltage cross the 0.1 resistor should be about 1 volt. But when I try to measure it, my voltmeter doesn't register anything (and the refrigerator is indeed powered by the extension cord). What am I doing wrong? Or is there a better way to meaure the current (besides buying an expensive AC current measure gauge)?
By the time you got a resistor the right size to actually impact the circuit enough. to actually measure the voltage you most likely would accomplish three things.
1. You may drop enough volts to mess up your fridge
2. The current readings won't be right anyways because you've change the resistance of the circuit.
3. Your resistor is going to end up popping unless its the size of a box of baking soda to handle all the wattage. Infact your lucky it didn't already as I doubt the leads are large enough to handle 8amps.
 
  • Like
Reactions: Speedy Petey

·
Banned
Joined
·
5,990 Posts
to measure the current required by my refrigerator.
10 watt 0.1 ohm resistor and spliced it into one of the wires (not the ground wire)
the refrig requires about 8 amps, so the voltage cross the 0.1 resistor should be about 1 volt.
my voltmeter doesn't register anything (and the refrigerator is indeed powered by the extension cord).
What am I doing wrong?
I think your calcs and assumptions are fine, even with a tricky load like a compressor.
Try different things to get clues or have a fresh pair of eyes look at it. The real learning takes place when things don't work as planned.
Keep the resistor in the neutral lead and not the hot lead.

A 100W, 100 ohm, resistor also comes in handy for household elec. troubleshooting (a guy at a hamfest gave me one for free), as does a hair dryer.

Knowing the basics
= less unnecessary purchases = more self-reliance = some slightly increased risk in return for more knowledge = possible fear/contempt/rage/ridicule from others.
 

·
Master Electrician
Joined
·
1,165 Posts
I'm glad I'm not the only one sitting here thinking he's running 8amps through a 50 cent resistor lol. There's a reason they invented the clamp on meter
 

·
Registered
Joined
·
3,923 Posts
What I have done to measure total appliance load is to buy a flat 3 wire heavy duty extension cord and split the hot lead from the rest of the cord. It makes it simple and easy to clamp an ammeter on the hot lead. Very simple and you don't need to take anything apart or "Rube Goldberg" something which may be dangerous.:whistling2:
 

·
Master Electrician
Joined
·
1,165 Posts
stickboy1375 said:
I generally just use the nameplate on the appliance, guess that's way to easy of an idea....
Lol ya seems to be. Although I've found fridges alway draw less than plate amperage. Unless you have the old style with the super chrome handles that lock in place and freeze your beer.
 
1 - 12 of 12 Posts
Top