# How to Read Labels on Electrical Products



## jamiedolan (Sep 2, 2008)

ElectricallyChallenged said:


> I'm calculating the electricity that I use everyday in my house and needed some clarification.
> 
> Could you break down what 120V/60Hz means?
> 
> ...


Labels are not an accurate way to determine usage. It will vary considerably from what a label reads. 

A Kill A watt device that reads how much current you are using might be what your looking for. 

Are you calculating this just from a cost standpoint?
Jamie


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## Yoyizit (Jul 11, 2008)

ElectricallyChallenged said:


> when a label shows a number like 14W. Does that mean that the product uses 14 watts when powered for an hour?


14W is a measure of power, and power is the rate that energy is expended. A watt is equal to one joule per second. 

14W for one hour is measure of energy, i.e., 14 watt-hours.

A typical house takes 1kW all the time, so for a month this is 720 kWh. At 10 cents per, this is $72/month.

A horsepower is = 746 watts; an average person can generate this much power for a half-minute. A world class cyclist can generate 400W for 20 minutes.


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## joed (Mar 13, 2005)

120v/60hz means 120 volts 60 hertz frequency as opposed to Europe where they use 240 volts and 50 hertz.
14 watts is 14 watts. If you used it for an hour it would be 14 watt hours or .014 kWh which is what you see on your power bill. The value printed on a device is an appoximate.
How much power a device uses depends on how often it runs. A fridge running all day won't be runing 24hours. It iwll be cycling on and off using maybe .3 kwh one hour and 0 kwh the next. The energuide rating helps you determine the actual usage for a day.


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## ElectricallyChallenged (Oct 26, 2008)

hey thanks a lot guys, i'm trying to figure out how many solar panels I would need, that's why i'm trying to figure this out. I looked into that kill a watt device and will most likely pick one up. 

When I've been shopping around for the panels it looks like the have them in watts and not kwh. im just trying to get a rough estimate on how much power i use, doesn't have to be exact. 

but my main question, i'm still not so clear on. so if it says 100W on a label, is this measured on a one hour basis. for example a 60W lightbulb will use 60 watts in one hour? thanks again.


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## jerryh3 (Dec 10, 2007)

ElectricallyChallenged said:


> hey thanks a lot guys, i'm trying to figure out how many solar panels I would need, that's why i'm trying to figure this out. I looked into that kill a watt device and will most likely pick one up.
> 
> When I've been shopping around for the panels it looks like the have them in watts and not kwh. im just trying to get a rough estimate on how much power i use, doesn't have to be exact.
> 
> but my main question, i'm still not so clear on. so if it says 100W on a label, is this measured on a one hour basis. for example a 60W lightbulb will use 60 watts in one hour? thanks again.


Watts do not have a time associated with them (sort of, as it was already pointed out it's one joule per second). It's a measure of current.


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## InPhase277 (Feb 9, 2008)

jerryh3 said:


> Watts do not have a time associated with them. It's a measure of current.


Huh?:huh: Watts is a measure of power which is the time rate of energy. Watts have a time associated with them in that a watt is a joule per second.

Current is measured in amperes.


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## 220/221 (Oct 9, 2007)

120v/60hz = 120 volts, 60 hertz...60 cycles per second "on/off"

Watts is power consumed. 

Volts x amps = watts.

Amps = watts divided by volts

A kilowatt is 1000 watts. 

A kilowatt hour (KWH) is 1000 watts running for one hour.

Solar is great for heating water and powering LED lighting.


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## Speedy Petey (Feb 1, 2004)

I think what Jerry meant was the wattage rating of an item is not related to the time it is used. 


A 60w light bulb uses 60 watts for as long as it is left on.


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## jerryh3 (Dec 10, 2007)

InPhase277 said:


> Huh?:huh: Watts is a measure of power which is the time rate of energy. Watts have a time associated with them in that a watt is a joule per second.
> 
> Current is measured in amperes.


I was trying to explain that the time unit is already factored into the definition of a watt.


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## Speedy Petey (Feb 1, 2004)

ElectricallyChallenged said:


> When I've been shopping around for the panels it looks like the have them in watts and not kwh.


That's because a kW is 1000 watts, and solar panels put out very little electricity. This is why you need so many of them.


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## InPhase277 (Feb 9, 2008)

jerryh3 said:


> I was trying to explain that the time unit is already factored into the definition of a watt.


I got'cha now.:thumbsup: But it still doesn't measure current.


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## jerryh3 (Dec 10, 2007)

InPhase277 said:


> I got'cha now.:thumbsup: But it still doesn't measure current.


How about current times voltage potential? It's late. My brain shut down a few hours ago.


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## joed (Mar 13, 2005)

You are confusing watts with watt-hours. Watts is an instantaeous power measurment. When you add time into it, it becomes a watt-hour or kilowatt-hour.
If you leave a 60 watt light on for one hour it uses 60 watt-hours. If you leave it on for two hours it uses 120 watt-hours.


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## Gigs (Oct 26, 2008)

You looking at grid-tie solar or off-grid?


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## Yoyizit (Jul 11, 2008)

Sunlight puts out 60w/sq. ft and solar panels are 7% efficient so they give 4w/sq.ft., so for 1kw you'd need 1000/4 = 250 sq. ft. of solar panels (that track the sun as it moves).
If you use parabolic mirrors heating pipes to supply hot water you get close to 100% efficiency.


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## joey b (Oct 18, 2008)

quite sure I read recently that solar panels are becoming more and more efficient. They are currently about 12% with the top ones at about 15%. An 18% effecient unit is expected to be available soon.


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## Gigs (Oct 26, 2008)

There's a lot of "press release products" when it comes to solar, especially with oil the way it was. Don't believe it until the "add to cart" link is live.


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## Yoyizit (Jul 11, 2008)

*correction*



joey b said:


> quite sure I read recently that solar panels are becoming more and more efficient. They are currently about 12% with the top ones at about 15%. An 18% effecient unit is expected to be available soon.


Apparently it's 130 w/sq ft if you include visible, ultraviolet and infrared light from the sun. I don't know how much of these wavelengths a solar panel picks up so I guess 130 is a max.


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## LittleLuLu27 (Dec 19, 2020)

ElectricallyChallenged said:


> I'm calculating the electricity that I use everyday in my house and needed some clarification.
> 
> Could you break down what 120V/60Hz means?
> 
> ...


You asked is 120v 60hz = 14watts 

Then you ask if watts is not provided then do you​multiple volts times hertz(sp) which​120v times 60z *IS NOT 14WATTS*​*7200 *sorry I don't know where the decimal goes​​​


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## Jim Port (Sep 21, 2007)

LittleLuLu27 said:


> You asked is 120v 60hz = 14watts
> 
> Then you ask if watts is not provided then do you​multiple volts times hertz(sp) which​120v times 60z *IS NOT 14WATTS*​*7200 *sorry I don't know where the decimal goes​​​


Thanks for contributing, but this question was from 12 years ago.

You do not multiply voltage and hertz. These are simply the characteristics of the electric supply.


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## chandler48 (Jun 5, 2017)

@LittleLuLu27 It's a 12 year old thread. But to clarify how you calculate things electric, here goes:


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## FrodoOne (Mar 4, 2016)

LittleLuLu27 said:


> You asked is 120v 60hz = 14watts
> 
> Then you ask if watts is not provided then do you​multiple volts times hertz(sp) which​120v times 60z *IS NOT 14WATTS*​*7200 *sorry I don't know where the decimal goes​​​


The Frequency of an AC supply is not important in calculating the Watts (Power) involved into a Resistive load.
"Power" is the RATE of doing Work.
One Watt is one Joule per second. 
If one Watt is used continuously for one hour there will be 3600 Joules used.
This Is one Watt-hour, for which you will pay appropriately to your electricity provider.

If you are using 14 Watts at a Supply Voltage of 120 Volts, the Current being drawn will be 0.117 Amps (117 milliamps).- if that is of any importance. (I = W/E or Current = Watts/Voltage)

(Note that, even in the USA, SI [the Metric System] *must* be used for such calculations - because there is no other form of measure for electrical quantities.)


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## Jackofall1 (Dec 5, 2010)

If you are looking a device to measure your usage you already have one, that is if you are buying power from the POCO, as this is how they determine your billing, granted for the entire house for what ever billing period. If you want specific usage per device then you might want to get your hands on a, "Clampon Amp Prode"









Measure amps x voltage of the device = watts/1000 = Kilowatts


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## joe-nwt (Jul 15, 2020)

Jim Port said:


> Thanks for contributing, but this question was from 12 years ago.
> 
> You do not multiply voltage and hertz. These are simply the characteristics of the electric supply.



Not true:

According to the de Broglie equations, for electromagnetic radiation energy is directly proportional to frequency: E = mc² = h·c/λ = h·ν where E is the energy; c = 299 792 458 m/s is the speed of light; λ is the wavelength; ν is the frequency and h = 6.62607015·10⁻³⁴ J·s is the Planck constant. Thus (1 J)/h = 1.509 190 311(67) × 10³³ Hz.


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## Jackofall1 (Dec 5, 2010)

@joe-nwt did you learn that in your first year or second year apprenticeship program? That is some deep crap right there, like a whole boat load of deep crap.


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## Jim Port (Sep 21, 2007)

I don't know if they ever got that deep on Big Bang Theory.


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## joe-nwt (Jul 15, 2020)

Jackofall1 said:


> @joe-nwt did you learn that in your first year or second year apprenticeship program? That is some deep crap right there, like a whole boat load of deep crap.


Nah. I just used google cuz I like to be a smart azz.


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