Subpanel
Also known as: Sub-panelsecondary panelfeeder panelADU panelSubpanelBranch panelSecondary panel
A subpanel is a secondary breaker panel fed from the main service panel via a "feeder" circuit. Used to extend electrical service to a part of the house (detached garage, ADU, basement workshop, addition) without running every individual circuit back to the main panel. The subpanel has its own breakers but no main disconnect (the main disconnect at the service panel covers it).
Subpanels in dwelling units must have a separate neutral and ground bus (they cannot be bonded together at the subpanel — only at the main service panel). This is one of the most commonly miswired things in DIY work; we see bonded-neutral subpanels regularly during inspections and fix them.
ADU construction is booming and almost every ADU needs a subpanel — runs from the main house feed, lands at the ADU exterior, distributes the ADU's circuits. Detached garages getting EV chargers often need a subpanel. Major kitchen + bath remodels sometimes warrant a subpanel.
We install Siemens sub-panels as our default — the same brand we use for main panels — because keeping the panel and breaker brand consistent means UL-listed compatibility, cleaner service coordination, and one warranty chain to manage. Square D or Eaton on request when a specific project has a reason to use one (existing brand match on a partial install, customer preference, or availability). Breakers always match the panel brand — that's UL-listing requirement, not stylistic choice. We don’t publish prices on the site. You get the cost in writing after a free inspection.
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