Wiring the Generator Inlet Without Wasting Watts

A portable generator already regulates voltage loosely — ±5% on a good set, worse as the tank empties. Whatever your inlet circuit drops comes straight out of that already-soft supply, which is why generator hookups deserve tighter wire than their breaker suggests.

The standard configurations

• 30 A / 120-240 V inlet (L14-30): 7,200 W ceiling — 10 AWG copper minimum by ampacity, on an interlock or transfer switch.
• 50 A inlet (14-50 or SS2-50): 12 kW class — 6 AWG copper minimum.

Where the volts leak

The circuit is inlet → panel plus the cord, and cords are the usual offender: a 50 ft, 10 AWG generator cord at 24 A drops about 2.9 V before the building wiring adds its share. Model the cord and the inlet run as segments — under 2% total keeps appliances happy when the generator itself sags under a well-pump start.

Three rules for the install

• Put the inlet close to the panel; spend distance on the cord, not the building wiring — cords are replaceable and upgradeable.
• Buy the 10 AWG cord, not the bargain 12 AWG one, for anything past 25 ft.
• During an outage, sequence the big motor loads — the generator's own regulation plus circuit drop is what trips overloads when the fridge, freezer and pump all start together.

Run your inlet distance through the solver at the inlet's full rating: undersized generator wiring wastes fuel you are buying by the gallon.