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Thread: Maximum load for a 120V USA wall outlet?

  1. #1
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    Maximum load for a 120V USA wall outlet?

    I'm posting this question here b/c a lot of you have farms setup drawing tons of electricity from your wall outlets.

    1) How many watts can a single 120V USA wall outlet handle?

    I have 2 desktops and 1 CRT monitor that likely draw 900W and I have them all plugged into 1 powerstrip which is then connected to 1 outlet.

    I live in a new place that has electrical wiring not even 1 year old.

    2) Would getting another powerstrip and plugging it into the outlet just above my current outlet be better?

    Thanks guys.

  2. #2
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    Scott is the right person to asnwer this question
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  3. #3
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    Historically, the most common household circuit is capable of delivering 15 amps, or 15a x 120v = 1800 watts. If your home is older, you can be nearly certain all but the specialized outlets in your home are rated at 15 amps (1800 watts).
    In most homes, esp. newer ones, some kitchen outlets are rated at 20 amps, or 2400 watts. These often feed the refrigerator, microwave, or garbage disposal and are dedicated to these appliances.

    If you don't mind turning circuit breakers on and off from the box and seeing what outlets they control, you could find out exactly what the circuit is rated since it is stamped right on the breaker switch.

    A final note, the amp rating on the circuit breaker is for ALL outlets and devices that are part of the circuit. So if you intend to draw close to the maximum, you may need to turn off everything else on the circuit.

    Note:
    One part of the electrical code limits the maximum plugged device to 80 percent of a sockets rating. Thus a 20amp socket can have a 16amp device; a 15 amp socket a 12 amp device. This is usually for devices plugged in for along time. Re "The rating of any one cord-and-plug-connected utilization equipment shall not exceed 80 percent of the branch-circuit ampere rating.

    Since circuit breaker circuit has usually many sockets and lamps; you can trip the breaker with less load than one would normally think.

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    Quote Originally Posted by Danger30Q
    I'm posting this question here b/c a lot of you have farms setup drawing tons of electricity from your wall outlets.

    1) How many watts can a single 120V USA wall outlet handle?

    I have 2 desktops and 1 CRT monitor that likely draw 900W and I have them all plugged into 1 powerstrip which is then connected to 1 outlet.

    I live in a new place that has electrical wiring not even 1 year old.

    2) Would getting another powerstrip and plugging it into the outlet just above my current outlet be better?

    Thanks guys.
    Add up the max amps draw of all devices and make sure it's not more than 80% of the circuit that the outlet is on. This assumes that there is nothing else on that circuit in another room etc..110 circuits are generally 15 or 20 amp..check your breakers in your panel for the size of that circuit.
    I had a dedicated 30 amp 110 line put in for my 2 main systems but thats because I have a large APC-Smart UPS 3000 running that draws 26 amps at startup.
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    You could also easily swap out a 15a breaker and put in a 20a or 30a. I live in a new place and almost all the breakers are 15a for the bedrooms/office. If I get another pc or two, I'm swapping out the breaker for a 30a. The wire should be fine...

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    Quote Originally Posted by Shaotai
    You could also easily swap out a 15a breaker and put in a 20a or 30a. I live in a new place and almost all the breakers are 15a for the bedrooms/office. If I get another pc or two, I'm swapping out the breaker for a 30a. The wire should be fine...

    That all depends on what kind of wire they used when installing all the electric!! most use 14-2 and you don't want to run over 15a breakers because the wires start to heat up above 15a!! you can use a 20a breaker on a 14-2 wire but the wires can get quite hot before the breaker kicks out if your haveing trouble with loads then I would say go get a 12-2 wire and run it from the box to a single outlet for your pc and put it on a 20a or 30a breaker!!!! but never put a 30a breaker on a 14-2 wire unless you want a big house fire!!!!!!



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    Quote Originally Posted by Shaotai
    You could also easily swap out a 15a breaker and put in a 20a or 30a. I live in a new place and almost all the breakers are 15a for the bedrooms/office. If I get another pc or two, I'm swapping out the breaker for a 30a. The wire should be fine...

    Amps for a breaker and wire size are directly related. Too small of a wire and a large breaker is a potential fire or meltdown.

    Have an electrician do the swap...then you are safe and if there is a problem it's his

    General rule of thumb[not a reccomendation]
    15A 14 gage wire
    20A 12gage wire
    30A 10 gage wire.

    Most wall circuits are either 14 or 12 gage depending on local/NEC codes.

    BE SAFE
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    Thanks a lot for the info. As it currently stands, I think having only 2 desktops and monitor connected to 1 outlet should be just fine. I doubt I will ever draw more than 1100 watts from a single outlet.

    I just bought a nifty gadget called the Kill-a-Watt that plugs into your wall outlet and then you connect your power cord to it. It then displays current volts, amps, or watts. It can also then help calculate total power consumption for the month based on a single day average:

    http://www.amazon.com/gp/product/B00...857436?ie=UTF8

    Found it on eBay for $25 shipped.

  10. #10
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    Follow mike047 advice. You do not want to fool around with overloading an electrical circuit.
    A Father and his young son were killed in a house fire less than 6 miles from me.
    Fire origin according to Fire Marshall: Electrical overload in room converted to home office with several computers and other electical devices. Be safe!
    Ask Serlv his electrical situation is exactly what prompted me to upgrade to a dedicated circuit. Thanks Serlv for bringing this to our attention.

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    Quote Originally Posted by mike047
    Amps for a breaker and wire size are directly related. Too small of a wire and a large breaker is a potential fire or meltdown.

    Have an electrician do the swap...then you are safe and if there is a problem it's his

    General rule of thumb[not a reccomendation]
    15A 14 gage wire
    20A 12gage wire
    30A 10 gage wire.

    Most wall circuits are either 14 or 12 gage depending on local/NEC codes.

    BE SAFE
    This guy knows his specs..perfect!
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    They just passed a law here, making it illegal to change anything in the house wiring except if via an electrician. And rightfully so.

    It is not about who to blame. It is about poutting your family life in danger. There is more to it than just the wire size and the breaker. Things like number of wires in condwit, short circuit capacity, derating due to insulation, voltage drop, etc.


    So guys, no MODDING of house wiring to boost the extra amps, pleeese
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    Quote Originally Posted by Movieman
    This guy knows his specs..perfect!

    yes he does!!!! and if you google it you will find the same chart that he wrote down to show everyone here!!



  14. #14
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    hehe.. last lan party I was at a bunch of morons plugged into my powerstrip without me knowing (couple hundred people in attendance) and it darn near caught fire !

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    some people just don't use there heads!!!! If your not sure about something then learn google is your best friend!!!!!



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    Quote Originally Posted by littleowl
    yes he does!!!! and if you google it you will find the same chart that he wrote down to show everyone here!!
    Nah google, I know wiring. I will tell you a funny story of when I was doing the electrical for my cabinet shop many many years ago. I had a Delta Cabinet saw.2hp 220V..Used a 20 amp 220 line. I decided to use 10/3 in case I wanted to upgrade the saw to the 5hp version. Also thought that since I would be running the line near the saw and saws will on occasion grab a piece of wood and launch it, that I would run the 10/3 through conduit. The only conduit that I'd ever personally seen was 1/2 inch EMT so I bought 30 feet of it and proceeded to "try" and run the 10/3 Romex through it..Yea, you got it, 2 nights and 4 million curse words later it was done using almost 1/2 a gallon of wire lube..Funny now, not then..All I needed to do was to have bought 1" EMT..
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  17. #17
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    Not much I can add here that hasn't been covered.

    Yes, it is dangerous to overload, obviously. We upgraded many of the circuits in the house to 20A, just to have the headroom. In otherwords to stay well within the 80%. When I say we I mean a good friend who is a master electrician and me.

    We also added 5 dedicated circuits. I had a circuit that had been seriously overloaded ( they stretched it from one end of the house to the other. I wasn't aware of that. Then I came along and threw a ton of machines on it ( before I started finding out about all this ). Over time I killed some receptacles, strained some wire, etc. Definitely created a fire hazard.

    Luckily I caught it in time.

    Things I found out. 9 machines ( and 2 monitors ) on a duplex is not good.
    If you are going to run 25 machines in your house you might want to check the load on each circuit.
    It is better to have 20A circuits then 15, and yes 12 guage is the right spec for 20A lines. Also, the receptacles for 20A lines are beefier ( and obviously, different then those for 15A lines ).

    We got out an ammeter ( not sure if that is what it is called ) and tested a few circuit's load with a few typical congig/loads for me.

    Found 3 OCed PCs (DX, 2 DCs), a switch and a monitor, on one circuit, pulled just under 7 Amps. Checked out some other loads, too, and, now, I am well under on any given circuit.

    By spreading out the loads to dedicated circuits we've given me a large margin for safety and taken the strain off theelectrical.

    I don't run 25 anymore, either.

    2 rigs on a circuit should be fine, as long as there is not a ton of other stuff on it, too.
    Last edited by [XC] serlv; 07-18-2006 at 05:43 PM.
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  18. #18
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    Quote Originally Posted by Movieman
    Nah google, I know wiring. I will tell you a funny story of when I was doing the electrical for my cabinet shop many many years ago. I had a Delta Cabinet saw.2hp 220V..Used a 20 amp 220 line. I decided to use 10/3 in case I wanted to upgrade the saw to the 5hp version. Also thought that since I would be running the line near the saw and saws will on occasion grab a piece of wood and launch it, that I would run the 10/3 through conduit. The only conduit that I'd ever personally seen was 1/2 inch EMT so I bought 30 feet of it and proceeded to "try" and run the 10/3 Romex through it..Yea, you got it, 2 nights and 4 million curse words later it was done using almost 1/2 a gallon of wire lube..Funny now, not then..All I needed to do was to have bought 1" EMT..
    Well, some of us do like it real tight. But, Dave, that's getting carried away!
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    Quote Originally Posted by Danger30Q
    I'm posting this question here b/c a lot of you have farms setup drawing tons of electricity from your wall outlets.

    1) How many watts can a single 120V USA wall outlet handle?

    I have 2 desktops and 1 CRT monitor that likely draw 900W and I have them all plugged into 1 powerstrip which is then connected to 1 outlet.

    I live in a new place that has electrical wiring not even 1 year old.

    2) Would getting another powerstrip and plugging it into the outlet just above my current outlet be better?

    Thanks guys.
    One outlet for me.. hmm. Rig in sig, plus Dell 900MHz, a 19" CRT, a 17" CRT, Altec Lansing 4.1 THX Speakers, Ext. HDD, mouse charger, camera charger, and printer. Never had any problems .
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  20. #20
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    Quote Originally Posted by serlv
    Well, some of us do like it real tight. But, Dave, that's getting carried away!
    LOL, I only had it THAT tight once..It was back in 1967 and..oops..I can't tell that story here..
    Crunch with us, the XS WCG team
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    Quote Originally Posted by Movieman
    LOL, I only had it THAT tight once..It was back in 1967 and..oops..I can't tell that story here..
    oh you brought it up now you must spill those beans or that magic beanstalk will be dead by morning

  22. #22
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    Quote Originally Posted by Mr_Slinky
    oh you brought it up now you must spill those beans or that magic beanstalk will be dead by morning
    Would love to but the PG rating of XS would be an XXX by the time I finished!
    And there was this Sicilian girl back in 1972..I was 20, she was 23..5'2" maybe 95 gorgeous pounds. Her twin brother didn't want me dating her,
    The guy was like 5'6" and 140lbs..I was 5'10" and 190 and solid back then.
    The guy called me outside one night..I looked at him and laughed..
    What I didn't know is that he was a pro boxer..Yea.. and me a street figher from Lynn.Mass....
    You know that old expression: He hit me with so many left's that I was begging for a right"...I'm here to tell you it's true. Thank god for a good chin.
    I finally got to him,but it took 10 mins to get him and my face looked like a watermellon the next day. Got the guy off his feet and nailed his kidneys till he stopped moving..
    I'll never underestimate a small guy again.
    Crunch with us, the XS WCG team
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  23. #23
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    ok that seems preaty decient granted you didn't have the morals or knowledge you have today. you were being lead around by soemthing else in those days wernt you

  24. #24
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    Quote Originally Posted by Mr_Slinky
    ok that seems preaty decient granted you didn't have the morals or knowledge you have today. you were being lead around by soemthing else in those days wernt you
    Moi? John, she was a doll, I mean a 10 pal..I probaly still have the marks on my back from that lady!
    I was an innocent child of 20 She was a worldly woman of 23
    Yea, good old Tommy Testosterone..He could really run your life at age 20..
    Crunch with us, the XS WCG team
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    Quote Originally Posted by Frisch View Post
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  25. #25
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    lol @ movieman!!!!!!!

    The only conduit that I'd ever personally seen was 1/2 inch EMT so I bought 30 feet of it and proceeded to "try" and run the 10/3 Romex through it..Yea
    I would have loved to seen that LOL



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