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# How much power is supplied to average household?

## How much power is supplied to average household?

#1
05-04-17, 09:40 AM
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Join Date: Jul 2016
Location: USA
Posts: 53
How much power is supplied to average household?

I have a few questions for you all. I'm trying to find out how much power is being supplied to an average home from the power line.

How many watts are supplied to a home and at what frequency?

How many amps typically? 200a?

How many volts are typically needed at once and how many total volts throughout an entire day? (Average or round about idea)

What size transformer? Phase 1?

What gauge wire brings power into the house to the breaker box?

#2
05-04-17, 09:50 AM
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Typical residential services in the US range from 60A to 200A with modern code for new homes requiring a minimum of 100A. Large homes can have up to 320A. The service is a single phase split into two legs which provides both 120V and 240V. At any given time a home only draws the power it is actually using by lighting and appliances. This is almost always much less than the maximum service rating.

Typical voltages generally vary about +/- 5% from nominal with fluctuations throughout the day and from season to season depending on system load. In the US and Canada, the frequency is 60Hz. The size of the wires and transformers depend entirely on the policies of the local power company, with consideration to the fact that in a populated area several homes will share a single larger transformer whereas in rural areas a single home may have it's own small transformer just due to length of cable runs between homes.

#3
05-04-17, 09:51 AM
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Location: NC, USA
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Look at the breaker panel. The top large main breaker will have a number on it. That is usually what's available to the house. 200 amp is common on more modern homes but older homes may only have 60 or 100 amps.

There are two 120 volt legs which when combined provide 240 VAC in The United States. Individual legs are used for the 120 volt circuits in the house while both are used for appliances like a stove and clothes dryer which need 240.

The transformer is sized for the load. Sometimes one transformer supplies more than one home or each home could have it's own. Most residential service is single phase.

The gauge of wire leading to the house depends on the size service. Older homes with 60 or 100 amp service often have smaller wires from the power company than a modern home.

Last edited by ray2047; 05-04-17 at 11:51 AM.
#4
05-04-17, 11:55 AM
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Join Date: Mar 2006
Location: USA
Posts: 29,711
It is a common misconception your home is supplied with two 120 v legs and they are combined to make 240 but this is not true. Your home supplied with 240 volts. 120 volts is derived from either of the 240 volt legs and the neutral which is really a center tap on the secondary of the transformer supplying your house.

#5
05-05-17, 11:02 AM
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Join Date: Jul 2016
Location: USA
Posts: 53
So basically there are 240v lines coming into the breaker box and then divided to 120v on the smaller breakers inside the box? Or are 120v lines divided somewhere else?

Thank you for the great answers

#6
05-05-17, 11:38 AM
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Location: NC, USA
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There are two lines carrying power into the house. Then the breaker panel is set up to one leg feeds alternating breaker slots and the other leg feeds the others. So, one 120v leg feeds all the even numbered slots while the other hot leg feeds all the odd numbered slots. When you plug in a single pole breaker it connects with only one hot line and you get 120 volts. When you install a double pole breaker it connects to two spots and it hooked up to both hot lines giving you 240v.

In addition to the two hot leads (black) coming into the breaker box there is a neutral (white). The Neutral (white) connects to the neutral buss bar in the panel which is also where the ground wires from the house wiring connect.

#7
05-05-17, 02:16 PM
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The legs on the panel are not left and right. They alternate ABABA from top to bottom.