Comments on: How to count capacity of electrical service panel? http://www.howto.com.my/2009/answer-this-if-you-can/how-to-count-capacity-of-electrical-service-panel/ Your How To Solution For Just About Everything Fri, 20 Jan 2012 12:43:10 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: wallmeishttp://www.howto.com.my/2009/answer-this-if-you-can/how-to-count-capacity-of-electrical-service-panel/comment-page-1/#comment-19525 wallmeis Mon, 09 Nov 2009 02:31:58 +0000 http://www.howto.com.my/2009/answer-this-if-you-can/how-to-count-capacity-of-electrical-service-panel/#comment-19525 As long as there is a main breaker (which protects the sum of all the other breakers), you can safely add circuits and loads until the main starts popping. The service panel capacity usually matches the utility meter base's capacity. And those tend to match the wires coming into the house. If, for example, the service is 200 amps and you wanted to upgrade, the next step up (at least in the Pacific Northwest) is 320 amps. That is 640 amps of 120 v circuits, or 320 amps of 240 v circuits. To directly answer your question, count the double breakers twice. However, breakers are allowed to total more than the main breaker's capacity. The main will have, for example, a pair of 100 amp breakers. This is a 100 amp service, and provides a total of 200 amps for this counting system. If, however, you have a split bus (like these http://i8.photobucket.com/albums/a8/JohnC1952/Electrical036.jpg http://www.tpub.com/content/construction/14027/img/14027_107_3.jpg http://www.inspect-ny.com/fpe/stlou022.gif ), consider replacing the panel since you can easily overload the service by adding or rearranging breakers. As long as there is a main breaker (which protects the sum of all the other breakers), you can safely add circuits and loads until the main starts popping.

The service panel capacity usually matches the utility meter base’s capacity. And those tend to match the wires coming into the house. If, for example, the service is 200 amps and you wanted to upgrade, the next step up (at least in the Pacific Northwest) is 320 amps. That is 640 amps of 120 v circuits, or 320 amps of 240 v circuits.

To directly answer your question, count the double breakers twice. However, breakers are allowed to total more than the main breaker’s capacity. The main will have, for example, a pair of 100 amp breakers. This is a 100 amp service, and provides a total of 200 amps for this counting system.

If, however, you have a split bus (like these http://i8.photobucket.com/albums/a8/JohnC1952/Electrical036.jpg http://www.tpub.com/content/construction/14027/img/14027_107_3.jpg http://www.inspect-ny.com/fpe/stlou022.gif ), consider replacing the panel since you can easily overload the service by adding or rearranging breakers.

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