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10-26-2008, 06:47 PM   #1
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## How to Read Labels on Electrical Products

I'm calculating the electricity that I use everyday in my house and needed some clarification.

Could you break down what 120V/60Hz means?

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

if it doesn't show the amount of watts, the label has to atleast contain the amount of volts and amps correct?

If it doesn't show the amount of watts, you get the wattage by multiplying the Volts by Amps correct? and once you determine that number its the number of watts used when powered for an hour?

please excuse the newbie questions, my board name explains it all.

Thanks

10-26-2008, 07:04 PM   #2
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Quote:
 Originally Posted by ElectricallyChallenged I'm calculating the electricity that I use everyday in my house and needed some clarification. Could you break down what 120V/60Hz means? when a label shows a number like 14W. Does that mean that the product uses 14 watts when powered for an hour? if it doesn't show the amount of watts, the label has to atleast contain the amount of volts and amps correct? If it doesn't show the amount of watts, you get the wattage by multiplying the Volts by Amps correct? and once you determine that number its the number of watts used when powered for an hour? please excuse the newbie questions, my board name explains it all. Thanks
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?
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10-26-2008, 07:08 PM   #3
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Quote:
 Originally Posted by ElectricallyChallenged 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.

 10-26-2008, 07:09 PM #4 Member     Join Date: Mar 2005 Location: Welland, Ontario Posts: 12,591 Rewards Points: 11,974 Blog Entries: 11 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. Last edited by joed; 10-26-2008 at 07:16 PM.
 10-26-2008, 07:47 PM #5 Newbie   Join Date: Oct 2008 Posts: 2 Rewards Points: 10 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.
10-26-2008, 08:04 PM   #6
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Quote:
 Originally Posted by ElectricallyChallenged 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.

Last edited by jerryh3; 10-26-2008 at 08:08 PM.

10-26-2008, 08:09 PM   #7
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Quote:
 Originally Posted by jerryh3 Watts do not have a time associated with them. It's a measure of current.
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.

 10-26-2008, 08:16 PM #8 Member   Join Date: Oct 2007 Posts: 2,294 Rewards Points: 1,000 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.
 10-26-2008, 08:19 PM #9 Licensed Electrical Cont.     Join Date: Feb 2004 Location: NY State Posts: 7,757 Rewards Points: 1,864 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. __________________ Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
10-26-2008, 08:20 PM   #10
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Quote:
 Originally Posted by InPhase277 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.

10-26-2008, 08:20 PM   #11

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Quote:
 Originally Posted by ElectricallyChallenged 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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Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.

10-26-2008, 08:28 PM   #12
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Quote:
 Originally Posted by jerryh3 I was trying to explain that the time unit is already factored into the definition of a watt.
I got'cha now. But it still doesn't measure current.

10-26-2008, 09:04 PM   #13
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Quote:
 Originally Posted by InPhase277 I got'cha now. But it still doesn't measure current.
How about current times voltage potential? It's late. My brain shut down a few hours ago.

 10-27-2008, 10:13 AM #14 Member     Join Date: Mar 2005 Location: Welland, Ontario Posts: 12,591 Rewards Points: 11,974 Blog Entries: 11 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.
10-27-2008, 02:05 PM   #15
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