Can a home backup generator power an EV charger, and do you need an interlock kit?

Yes, if the generator's continuous wattage rating covers the charger's current setting plus everything else drawing power at the same time. A Level 2 charger's draw is arithmetic, not a mystery: at 240 volts, a charger set to 16 amps draws 3.84 kW continuous, 24 amps draws 5.76 kW, 32 amps draws 7.68 kW, and 48 amps draws 11.52 kW. Almost every Level 2 charger sold today lets you set that current lower in software, which is the cheapest lever available if your generator's continuous rating doesn't clear the charger's factory-default setting.

The number that matters is the generator's continuous or running watts rating, not its peak or surge rating -- a spec sheet's larger, more prominent number. A generator rated for 8,500 running watts can comfortably carry a 16-amp or 24-amp charger setting alongside a refrigerator and some lighting; the same generator asked to also carry a 48-amp charger setting plus a well pump and a furnace blower will trip on overload. Turn the charger down before you assume you need a bigger generator.

A generator interlock kit is a mechanical device fitted to a home's breaker panel that physically prevents the main utility breaker and a generator-feed breaker from both being switched on at the same time. NEC Article 702 governs optional standby systems -- the category a portable or non-emergency backup generator falls into -- and requires suitable transfer equipment designed to prevent inadvertent interconnection of the utility and generator sources. Interlock kits are widely used as that transfer equipment for a residential panel, in place of a separate automatic or manual transfer switch, when the kit is listed for the exact panel model it is installed in and installed per its listing instructions.

That listing requirement is not a formality worth skipping. Multiple interlock kits on the market are lab-tested to a UL safety standard without carrying the UL Listing mark itself, and some electrical inspectors will not approve a kit that lacks that mark for your specific panel model, regardless of how it tested. Confirm with your AHJ and buy the kit made for your panel's exact make and model before wiring anything.

Because it sends power backward through the house wiring and out through your utility meter onto the grid, with no mechanical safeguard stopping it. Multiple electric cooperatives describe the mechanism plainly on their own safety pages: a generator connected this way can re-energize the line a utility crew believes is dead, and the neighborhood transformer that normally steps voltage down for your house steps a backfed generator's output back up onto the primary distribution line, at a voltage that can kill a lineworker without warning.

A dryer or range outlet also has no overcurrent protection sized for that use and no interlock stopping both sources from being live at once -- it is the same hazard an interlock kit or transfer switch exists specifically to prevent, done without the safeguard. This is the reason an interlock kit or transfer switch is not an optional convenience for backup power; it is the thing standing between a generator and a live utility line.

Either can satisfy the NEC's transfer-equipment requirement; they solve the same problem two different ways. An interlock kit is a mechanical block at the panel, cheaper and simpler, but it requires you to manually flip breakers in the right order every time you switch sources, and it only works with a portable or manually-connected generator. A transfer switch, manual or automatic, is a dedicated piece of equipment wired to specific circuits and is what most permanently-installed standby generators use, at a higher cost.

Add up the continuous wattage of everything you actually intend to run at the same time as the charger, then choose the charger's current setting so the total fits comfortably under the generator's continuous rating, not its peak rating.