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How many watts are there in a standard outlet?

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April 4, 2012 7:37:09 AM

What is the maximum output of a standard electrical outlet?

If I have a PC with a 1,500 power supply, do I need to plug it into two separate circuits? Or a 220V outlet?

Such a PSU could result in blown circuit breakers and electrical problems.

The only things that use that kind of power are household appliances such as washers, dryers, refrigerators, etc..

More about : watts standard outlet

a b ) Power supply
April 4, 2012 7:57:00 AM

It will probably be 1500w (6.81A @ 220V) at peak usage, normally outlets are marked in amps, just devide watts with voltage to get the ampage rating (W/V=A).
Typically a standard UK power outlet is rated at 240V and at 13A which works out to 3120W, I've never seen a standard plug type appliance (Fan Heaters and Air Cons ) rated at higher than 3000W.
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April 4, 2012 1:42:35 PM

Assuming you're in North America, a 120V receptacle is going to be on a 15A breaker; so ~1800W.

Edit: My mistake, 20A is as common or more so than 15A. Therefore ~2400W if this is the case. Easiest way to check is to go to your breaker panel and locate the breaker your computer is on (keeping in mind several outlets could be on one breaker so tread lightly.)
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a b ) Power supply
April 4, 2012 3:41:13 PM

You're right to consider the capacity of the outlet. Bear in mind a couple of other things.

1. Whatever the maximum wattage rating of the PSU, that is NET power available to the computer. But the PSU has an Efficiency rating, which is the % of power consumed actually available. A good PSU will have 80% or slightly better efficiency. One rated for 1000W would actually consume from the wall outlet 1250 watts IF the computer were actually using all 1000W available.

2. Consider also any other device plugged into the same circuit, such as printers, speaker amps, monitors, etc. And I said "circuit", not just "outlet". Many circuits have more than one outlet connected into them. A "circuit" is one power line fed from a single breaker (or fuse) in the main panel. The circuit's limit, as MightEMatt said, is set by the circuit breaker (or fuse) rating.

3. In designing circuit wiring for a house, a rough rule of thumb used is that the planned use of the circuit (its regular load) should not exceed 80% of the circuit breaker rating. So, one would plan that a 20A circuit should normally have a maximum steady load of 16 amps. Now, that is NOT a strict requirement. It is used mainly to avoid having the breaker trip off unnecessarily because of some transient surge when it is already operating near it limit. But the breaker AND the wires in the walls are designed to operate continuously and safely very close to the amp limit stated. In fact, most breakers will not trip right at their rated limit unless the load is kept there for a long time.
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April 4, 2012 3:50:07 PM

ambam said:
What is the maximum output of a standard electrical outlet?

If I have a PC with a 1,500 power supply, do I need to plug it into two separate circuits? Or a 220V outlet?

Such a PSU could result in blown circuit breakers and electrical problems.

The only things that use that kind of power are household appliances such as washers, dryers, refrigerators, etc..


A 1500w PSU will fit into a normal house outlet. But I'd reccomand having that outlet on a seperate breaker then everything else. Also you might consider using an isolated outlet but its not required (just be sure to use a good powerbar to prevent damaging your system).

Some poeple use a 3wire cable (will requier 2x 15Amper breaker) on the outlet so they can have both slut to get 1800w (this is the set-up I'm going on the house I'm building next summer). That way you can fit your system + speakers a lamp etc into the same outlet with no worries.

I'm an electrician so you can rely on me for that.

Edit: Don't do the msitake to change your 15amp breaker for a 20amp. If you do just don't be surprised if your house is on fire someday.
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a b ) Power supply
April 4, 2012 4:45:59 PM

The three-wire cable and duplex breaker system that venur suggested also requires that the outlet in the wall be modified slightly when installed, so that it becomes what's called a "split duplex receptacle". This is common in North American 110 / 220VAC systems, especially in kitchens, but I'm not sure about Europe or elsewhere - depends on where OP lives. OP, if you are not good a wiring houses, consult an electrician about that option. But, maybe you don't need that. After all, your original post was worded as a hypothetical, sounding like, "Suppose I had a 1500W PSU, could I run it off a standard wall outlet?" I do not expect you actually do have such a power supply. If you do, why?

I heartily agree with venur on the warning about changing to a higher-capacity breaker. DON'T!! The wiring in the wall MUST match the breaker rating, or as venur says, you are asking for flames!
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April 4, 2012 9:03:56 PM

Paperdoc said:
The three-wire cable and duplex breaker system that venur suggested also requires that the outlet in the wall be modified slightly when installed, so that it becomes what's called a "split duplex receptacle". This is common in North American 110 / 220VAC systems, especially in kitchens, but I'm not sure about Europe or elsewhere - depends on where OP lives. OP, if you are not good a wiring houses, consult an electrician about that option. But, maybe you don't need that. After all, your original post was worded as a hypothetical, sounding like, "Suppose I had a 1500W PSU, could I run it off a standard wall outlet?" I do not expect you actually do have such a power supply. If you do, why?

I heartily agree with venur on the warning about changing to a higher-capacity breaker. DON'T!! The wiring in the wall MUST match the breaker rating, or as venur says, you are asking for flames!


http://www.tomshardware.com/forum/341422-31-recommend-c...

Will the silverstone 1.5KW power everything that's in this rig?

I've spent YEARS saving up many thousands of dollars for my dream PC.
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April 4, 2012 9:31:44 PM

ambam said:
http://www.tomshardware.com/forum/341422-31-recommend-c...

Will the silverstone 1.5KW power everything that's in this rig?

I've spent YEARS saving up many thousands of dollars for my dream PC.


4x sli 680gtx isn't realy a great idea I'd say. It show realy minor improvement over 3x sli/CF. You'll probably be upgrading your GPUs for the same game a 3x sli user will but you'll spend 700-800$ more.

In the case you still want to go with a 4sli well we could send each other a few parse later on. I went with this case + PSU combo: http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

And I'm waiting for ivy bridge and 680gtx 4G to go the exact same build as you (but only 8GB 1600Hz since its a gaming rig and 3x sli) and you'll probably end with 5% FPS increase over me in a eyefinity set-up.

But I suggest you do some research on the net to see by yourself the minor gain 4x get over 3x for gaming. I was going for a 4x sli myself at first untill I've seen how poorly it is performing. I have an illimited budget for my PC but I won't spend my money on a useless feature.
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April 4, 2012 9:42:34 PM


15amp/14ga circuit: 120x15x.8 = 1440w

20amp/12ga circuit: 120x20x.8 = 1920w

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April 4, 2012 10:05:02 PM

venur said:
4x sli 680gtx isn't realy a great idea I'd say. It show realy minor improvement over 3x sli/CF. You'll probably be upgrading your GPUs for the same game a 3x sli user will but you'll spend 700-800$ more.

In the case you still want to go with a 4sli well we could send each other a few parse later on. I went with this case + PSU combo: http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

And I'm waiting for ivy bridge and 680gtx 4G to go the exact same build as you (but only 8GB 1600Hz since its a gaming rig and 3x sli) and you'll probably end with 5% FPS increase over me in a eyefinity set-up.

But I suggest you do some research on the net to see by yourself the minor gain 4x get over 3x for gaming. I was going for a 4x sli myself at first untill I've seen how poorly it is performing. I have an illimited budget for my PC but I won't spend my money on a useless feature.


So should I go with x3 GTX 680 instead of four?

What about two GTX 690's when they come out?
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April 4, 2012 11:57:23 PM

venur, last I looked, a 115V, 20Amp outlet and power cord have a completely different socket/plug than a standard 115V, 15Amp household outlet.
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April 5, 2012 12:26:28 AM

(North America)
Putting the computer on its own circuit is a great idea but it may not be easy to do. For example, around where I live the houses that are maybe 40 years old, and possilbly even the new ones, have all the outlets of the bedrooms on the same circuit. So if your computer is in a bedroom and someone fires up a hair dryer in another bedroom pop will go your breaker. Older houses can be much worse. It would be a good idea to determine what else is on the same circuit as your computer outlet. Lights and outlets are normally on separate circuits.

I'm working my way through a new build and had just come across the idea that it would be nice to have the new, and much more powerful, pc on its own circuit. Luckily my pc is in the living room and my breaker box is in a utility room immediately under my desk so it won't be too difficult to bring in a new 20 amp circuit.
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April 5, 2012 5:53:57 AM

Finally I have an unlimited budget to build my dream PC.

I'm waiting for the 4GB Kepler cards and the Intel Ivy Bridge.
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!