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Old 07-20-2012, 09:15 AM   #1
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measure current to refrigerator


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)?

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Old 07-20-2012, 09:18 AM   #2
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measure current to refrigerator


The refrigerator data plate will have the information on it. Look near a door for a sticker.

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Old 07-20-2012, 09:30 AM   #3
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measure current to refrigerator


get one of these. They are cheap and much more accurate than you will get the way you're going about it. Sold at many big box stores and online.

http://www.p3international.com/produ.../p4400-ce.html
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Old 07-20-2012, 09:50 AM   #4
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measure current to refrigerator


Quote:
Originally Posted by tfox37380 View Post
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.



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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-Internation.../dp/B00009MDBU
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Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.
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Old 07-20-2012, 10:25 AM   #5
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measure current to refrigerator


Quote:
Originally Posted by tfox37380
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.
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Old 07-20-2012, 11:09 AM   #6
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Some of the questions on here make me gasp at times.
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Old 07-20-2012, 11:17 AM   #7
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measure current to refrigerator


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Originally Posted by tfox37380 View Post
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.

Last edited by Yoyizit; 07-20-2012 at 11:29 AM.
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Old 07-20-2012, 06:02 PM   #8
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measure current to refrigerator


Your meter is faulty !
Or you use the wrong input / setting.

It is dangerous !
Be really careful !
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Old 07-20-2012, 06:51 PM   #9
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measure current to refrigerator


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
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Old 07-20-2012, 06:56 PM   #10
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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
I generally just use the nameplate on the appliance, guess that's way to easy of an idea....
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Old 07-20-2012, 08:05 PM   #11
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measure current to refrigerator


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.
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Last edited by Missouri Bound; 07-20-2012 at 08:08 PM.
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Old 07-20-2012, 08:43 PM   #12
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measure current to refrigerator


Quote:
Originally Posted by stickboy1375

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.

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