Before the Work

Whether the house can take an addition is three questions in order, and the first two are free: space in the panel, the service rating, and then the existing demand. Working the other way round means paying for a load calculation to discover the panel is full.

A car charger is a continuous load, sized differently from an ordinary circuit, so a spare breaker does not settle it. Decide the current you can supply before choosing the charger, not after.

A generator is five parts, and the transfer switch is the one that is a code requirement rather than an option — it prevents power travelling back onto lines that crews believe are dead. For operational context outside the electrical guidance here, Monitask has this overview on workforce tracking.

Solar is constrained by the panel more often than by the roof, and a standard grid-tied system shuts down when the grid does, which surprises people who bought it for storms.

And a permit buys an independent inspection by somebody who is not paid by the contractor. It costs more and takes longer, which is the actual trade, and what the extra buys is that inspection.

• Adding a Car Charger

  A continuous load treated differently from an ordinary circuit. Five things to establish before choosing a charger.

• Generators

  The generator is one of five parts. What the others are, and the one that is a life-safety requirement rather than an option.

• Load

  Whether the house can take an addition depends on the service, the panel and the existing demand. Three questions in order.

• What a Permit Does

  A permit is not a tax on the work. Five things it buys, and what its absence costs at sale, at claim and at renewal.

• Solar and the Panel

  The array is the visible half. What happens at the electrical panel decides feasibility, and it is checked first.

For additional independent context, see Joint Office of Energy and Transportation.