200 amps of service... help!!!


Old 07-23-05, 05:11 PM
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200 amps of service... help!!!

i have a question that might be a stupid one but i'll ask anyway. my house has a 200 amp/240 service coming to it. i've asked a couple people and they tell me that i have 200 amps period whether it's 240 volts or 120 volts. now, from a math standpoint that doesn't make any sense to me because 200 amps would allow me 48,000 watts @ 240 volts but only allow me 24,000 watts @ 120 volts.

so my question is this: if i have a 200 amp service can i run 48,000 watts or 24,000 watts at 120 volts?

in my mind, i should have 48,000 watts at 120 volts. in other words, i should be about to run 480 ea. 100 watt light bulbs at 120 volts.

any help will be appreciated.
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Old 07-23-05, 06:36 PM
hornetd's Avatar
Join Date: Aug 2001
Location: Maryland
Posts: 695
Exclamation Watts are a constant in your case

The Service will deliver 48000 watts at either voltage. The nominal size of the service is based on the size of the service entry conductors needed to serve the calculated load. If your service entry conductors are 2/0 copper or 4/0 Aluminum then those conductors will safely carry two hundred amperes on each ungrounded conductor. A 240 volt load will draw current from both ungrounded conductors. A 120 volt load will only draw from one of them. Since each of those conductors can carry two hundred amperes you have two hundred amperes available at 240 volts for a total of 48 Kilowatts or four hundred amperes available at 120 volts for a total of 48 Kilowatts. What you actually draw is some combination of the two that cannot be more than the 48,000 watts that the service can deliver.

I hope that helps.
Tom Horne
Old 07-23-05, 07:05 PM
Join Date: Sep 2000
Location: United States
Posts: 18,497
Probably one source of the confusion is the fact that no single wire can ever carry more than 200 amps. But, as Tom said, you do have access to 48KW, and that's all that really matters.
Old 07-24-05, 05:52 AM
ElectricalMan's Avatar
Join Date: Feb 2005
Location: Harrisonburg
Posts: 744
In simplified terms.......you do have 48KW available to you.....just think of it as 24KW on each LINE.........24KW + 24KW is 48KW

The reason for this is to ensure you keep the load balanced as possible which is why the panel board is staggered.....to give you access to both 24KW lines to get your total 48KW.

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