Can you measure wall current with a digital multimeter?
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Lewguitar
Guest
Re: Can you measure wall current with a digital multimeter?
I think so...
I'd guess you'd set it to VOLTS and set the range of the multimeter to the approx. voltage you'd expect and then stick the probes in your wall outlet.
Never done it though.
Maybe wait until someone who has done this posts and confirms that this is doable.
Lew
I think so...
I'd guess you'd set it to VOLTS and set the range of the multimeter to the approx. voltage you'd expect and then stick the probes in your wall outlet.
Never done it though.
Maybe wait until someone who has done this posts and confirms that this is doable.
Lew
S
stratobastard
Guest
tone4days
Heel Whacker
Re: Can you measure wall current with a digital multimeter?
you can follow lew's post for measuring the wall voltage ... should be in the ~110VAC to ~120VAC range or so ... be very careful that you do not touch the probes' metal ends or you'll get zapped ... this will give you an idea if your AC source is in a good range or if it is 'browning out' a bit by being undervoltage ...
current is measured in amps ... most residential circuits are going to be in the 15A range (meaning if you try to draw more than that, the circuit breaker will trip) ... measuring AC current is usually done by using an induction probe that goes around the power cord while the device is in operation .. according to kirkoff's law (am i remembering that correctly?), you can not measure AC current by putting the multimeter in series with the device under test (let alone that trying to do that would be hella stupid and potentially lethal)
you can follow lew's post for measuring the wall voltage ... should be in the ~110VAC to ~120VAC range or so ... be very careful that you do not touch the probes' metal ends or you'll get zapped ... this will give you an idea if your AC source is in a good range or if it is 'browning out' a bit by being undervoltage ...
current is measured in amps ... most residential circuits are going to be in the 15A range (meaning if you try to draw more than that, the circuit breaker will trip) ... measuring AC current is usually done by using an induction probe that goes around the power cord while the device is in operation .. according to kirkoff's law (am i remembering that correctly?), you can not measure AC current by putting the multimeter in series with the device under test (let alone that trying to do that would be hella stupid and potentially lethal)
Re: Can you measure wall current with a digital multimeter?
T4D gave you very good advice ...BE CAREFUL
If you are in Europe, be twice as careful...or don't even think of doing this.
Also, if your meter is not autoranging be VERY sure that you have it set up correctly before taking the voltage measurement...or...you will be buying a nice new meter.
Why do you you want to do this? The readings will fluctuate based on several factors.
If you are concerned about poor quality of AC supply from the wall, you might want to look a a power conditioner, or something similar.
Dave
T4D gave you very good advice ...BE CAREFUL
If you are in Europe, be twice as careful...or don't even think of doing this.
Also, if your meter is not autoranging be VERY sure that you have it set up correctly before taking the voltage measurement...or...you will be buying a nice new meter.
Why do you you want to do this? The readings will fluctuate based on several factors.
If you are concerned about poor quality of AC supply from the wall, you might want to look a a power conditioner, or something similar.
Dave
skyydogg01
Active member
J Moose
New member
Re: Can you measure wall current with a digital multimeter?
Truth!
And remember...it's not the volts that kill, it's the amps.
FWIW...I think Radio Shack still sells dedicated testers for this sorta thing...you could probably get one from a "real" electrical supply house too...the kinda place where electricians buy their tools.
Truth!
And remember...it's not the volts that kill, it's the amps.
FWIW...I think Radio Shack still sells dedicated testers for this sorta thing...you could probably get one from a "real" electrical supply house too...the kinda place where electricians buy their tools.
Soujurn
New member
Re: Can you measure wall current with a digital multimeter?
You can use a little ohms law to find out the current being drawn from the wall outlet.
Memorize this little mnemonic. P=IE
Power = Current x Voltage.
Current = Power/Voltage.
If a device is rated at 120 volts, and printed on it somewhere is the power rating, say 50 watts.
Then, Current = 50/120 or 0.4167 amps, which is 417 milliamps.
You can use a little ohms law to find out the current being drawn from the wall outlet.
Memorize this little mnemonic. P=IE
Power = Current x Voltage.
Current = Power/Voltage.
If a device is rated at 120 volts, and printed on it somewhere is the power rating, say 50 watts.
Then, Current = 50/120 or 0.4167 amps, which is 417 milliamps.
tone4days
Heel Whacker
Re: Can you measure wall current with a digital multimeter?
ohms law doesnt work with AC ... and there are several other problems with your assertion ... knowing the power consumed is no easier than determining the current - the number written on the label is a max power consumption and you have to know which operating conditions must be met in order for those ratings to apply ... and you have to know the power factor (which is 1 in a DC circuit, but NOT 1 in an AC circuit under almost all circumstances)
ohms law doesnt work with AC ... and there are several other problems with your assertion ... knowing the power consumed is no easier than determining the current - the number written on the label is a max power consumption and you have to know which operating conditions must be met in order for those ratings to apply ... and you have to know the power factor (which is 1 in a DC circuit, but NOT 1 in an AC circuit under almost all circumstances)
noth
New member
Re: Can you measure wall current with a digital multimeter?
Of course, usually the term "measuring wall current" is a misnomer. Voltage is usually being measured. A decent auto-ranging digital multimeter is best for that; investing in a Fluke is not cheap but well worth it in the long run, for that and all sorts of guitar electronics measurements.
The actual current depends of course on what's plugged in and running. That's what "pulls" current from the wall. Using the formula is theoretically correct but will probably be wrong because the wall voltage is varying all the time - you can't assume it's 117 or 120. Meters that measure current have a built-in "shunt", but must be measured "in-line", which can be dangerous. I wouldn't recommend it unless you're a tech. There are other ways to measure current with a voltmeter, but they're best left to techs and engineers.
Noth
Of course, usually the term "measuring wall current" is a misnomer. Voltage is usually being measured. A decent auto-ranging digital multimeter is best for that; investing in a Fluke is not cheap but well worth it in the long run, for that and all sorts of guitar electronics measurements.
The actual current depends of course on what's plugged in and running. That's what "pulls" current from the wall. Using the formula is theoretically correct but will probably be wrong because the wall voltage is varying all the time - you can't assume it's 117 or 120. Meters that measure current have a built-in "shunt", but must be measured "in-line", which can be dangerous. I wouldn't recommend it unless you're a tech. There are other ways to measure current with a voltmeter, but they're best left to techs and engineers.
Noth
kmcguitars
GuitarArtologist
Re: Can you measure wall current with a digital multimeter?
Why? One night I was troubleshooting my Princeton. My B+ was way high,Off the charts? I took a reading of the wall jack and it was 132 ACV:werd: As where the rest of the outlets in the house. ALL 132 ACV?? the next morning when I got up , I checked agian... It was 120 ACV. And My B+ was back in range.
Why? One night I was troubleshooting my Princeton. My B+ was way high,Off the charts? I took a reading of the wall jack and it was 132 ACV:werd: As where the rest of the outlets in the house. ALL 132 ACV?? the next morning when I got up , I checked agian... It was 120 ACV. And My B+ was back in range.
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That90'sGuy
DyzaBoyzologist
Re: Can you measure wall current with a digital multimeter?
It was said before, but it bears repeating, the only reading you can get from a wall receptacle while it's live without breaking the circuit is AC voltage. There are three holes on a receptacle, the two slots that are next to each other are the hot and neutral inputs and the distinct, rounder hole is your ground... you want to measure the hot and neutral.
As far as current goes, that's a whole different ballgame. To measure current, you need to break the circuit on one side (neutral or hot) and put the probes in series.
There is one quote in here that is VERY important and props to JMoose for mentioning it: ...it's not the volts that kill, it's the amps. Remember kids, 1/10th of an amp can kill you given the right situation... that's 100 mA in the right situation (not much, is it?). Most household circuits (in the US anyways) are 15A or 20A unless you're talking circuits for ranges, washers/dryers and the like.
Ohm's law is pretty much the universal way of figuring out the resistance, current and voltage in a circuit. It becomes a little complex when comparing AC to DC because AC stands for alternating current which means current flows both ways in the circuit... DC is direct current which means it only flows in one direction. Ohm's law can be used for AC as well as DC.
Soujurn is correct with the formulas, but for calculating power, a power factor does need to be applied (which is what tone4days was addressing).
It was said before, but it bears repeating, the only reading you can get from a wall receptacle while it's live without breaking the circuit is AC voltage. There are three holes on a receptacle, the two slots that are next to each other are the hot and neutral inputs and the distinct, rounder hole is your ground... you want to measure the hot and neutral.
As far as current goes, that's a whole different ballgame. To measure current, you need to break the circuit on one side (neutral or hot) and put the probes in series.
There is one quote in here that is VERY important and props to JMoose for mentioning it: ...it's not the volts that kill, it's the amps. Remember kids, 1/10th of an amp can kill you given the right situation... that's 100 mA in the right situation (not much, is it?). Most household circuits (in the US anyways) are 15A or 20A unless you're talking circuits for ranges, washers/dryers and the like.
Ohm's law is pretty much the universal way of figuring out the resistance, current and voltage in a circuit. It becomes a little complex when comparing AC to DC because AC stands for alternating current which means current flows both ways in the circuit... DC is direct current which means it only flows in one direction. Ohm's law can be used for AC as well as DC.
Soujurn is correct with the formulas, but for calculating power, a power factor does need to be applied (which is what tone4days was addressing).
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J Moose
New member
Re: Can you measure wall current with a digital multimeter?
Yup...a Boss 9-volt adapter supplies about 200mA at 9 volts.
Lethal dosages are ALL around us...
Yup...a Boss 9-volt adapter supplies about 200mA at 9 volts.
Lethal dosages are ALL around us...
ImmortalSix
John Mayer's Mankini
Re: Can you measure wall current with a digital multimeter?
Hot = Short slot
Neutral = Long slot
Ground = round slot
Hot to neutral = line voltage; should be 110-120 but 105-130 is not the end of the world. Outside these parameters, don't plug in.
Hot to ground should be >= (greater than or equal to) line voltage. This means your path to ground is adequate to handle the load if something goes wrong.
Neutral to ground should be less than 2 volts.
Hope that helps.
-Hunter
Hot = Short slot
Neutral = Long slot
Ground = round slot
Hot to neutral = line voltage; should be 110-120 but 105-130 is not the end of the world. Outside these parameters, don't plug in.
Hot to ground should be >= (greater than or equal to) line voltage. This means your path to ground is adequate to handle the load if something goes wrong.
Neutral to ground should be less than 2 volts.
Hope that helps.
-Hunter
Robert Delahunt
Showmasterologist
Re: Can you measure wall current with a digital multimeter?
Current? That's measured in amps, so unless you have an A and a ~ on your multimeter, no. If you wanted to know how many amps you can push, check your fuse box for the A # (like 25A is 25 amps, etc).
Volts? Sure. Set to V with ~ and there you go (since wall power in USA is alternating current... you're in USA right?).
Watts? Multiply what you get reading volts by the amp fuse that applies, and that's your theoretical max watts.
Why are you reading this stuff?
Current? That's measured in amps, so unless you have an A and a ~ on your multimeter, no. If you wanted to know how many amps you can push, check your fuse box for the A # (like 25A is 25 amps, etc).
Volts? Sure. Set to V with ~ and there you go (since wall power in USA is alternating current... you're in USA right?).
Watts? Multiply what you get reading volts by the amp fuse that applies, and that's your theoretical max watts.
Why are you reading this stuff?
