ECN Forum Forums General Topics of the Trade General Discussion Area Twin breakers or Sub-panel?

The subpanel next to the main panel is for the circuits that are displaced for the feeder connections. If the main panel is full, you need to move four poles to the subpanel, freeing four poles in the main panel. Then, two of those poles feed the new subpanel, and the other two feed the remote subpanel with all the new circuits.

You can, of course, also put some of the new circuits on the subpanel next to the main panel.