US Homes Face Costly Retrofits for Induction Stoves, EV Chargers | New homes in the US may not be “electrical ready” after an international standards agency excluded building electrification measures
More backstory they are an electrician and he has installed several chargers already. They were not intoxicated during the process, least as far as I can tell for drinking 2 bud lites for an hour+ of work
Coming as someone who did the same themselves, basically all mains wiring is good up to 600v in the US, and all main and sub panels have breakers precisely because you can overload them just by using a decent portion of your circuits to their fullest.
Putting in new circuits or plugs isn’t exactly uncommon or particularly difficult. The biggest thing to watch out for being the extra 20% safety margin the NEC requires on top of a circuits rated capacity that if I remember correctly puts you a gauge up from what the circuit itself requires, but if the state certified inspector signed off on it then it’s almost certainly good to go.
There's no difference between two 20A 120V circuit and one 40A 240V circuit. Two 12/2 vs one 10/3. Two breaker slots vs 1. Each conductor in the 240V circuit is the same volts as the hot of the 120V circuit. All fire risks and such are essentially identical.
You should not do home repair beyond your comfort zone, especially electrical. That said, there's nothing particularly spooky going on here.
Wiring up 240V circuits with 60A fuses was literally something many British and Irish kids did before their teens before the 90s. You had to wire plugs for every new item you bought as they were sold separately. Plugs has 13A fuses, so current was more limited... Unless you wired it wrong...
The 2 main basics that you need to be safe are these: Turn off the correct breaker, and doublecheck that it is turned off with a voltmeter before you touch anything.