I want to add a sub panel 100’ from my main 110 panel to power my new addition to my house. Question can I use a #2 wire on a 80amp breaker to my sub panel and have the wire in place for upgrade later to a 220 service and sub panel to a 100 amp will I run in to problem in the year between projects?

1 Answer 1


2 AWG copper with 75C rating will get you over 100A. However, 2 AWG aluminum is a lot cheaper and will only get you to 90A when used this way. (As I understand it, there are main service feed calculations which allow higher service on 2 AWG aluminum, but not on a subpanel feed.) So the question then is whether you will really need 100A or whether 90A is enough. Which depends on:

  • Size of building
  • HVAC requirements
  • Large built-in appliances
  • Type of water heating (gas is no or minimal electric, tanked water low electric, on demand electric can use 100A all by itself)

and a bunch of other factors.

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