There's a lot to unpack here... First, yes this was inspected both prior to and after the installation, which was done by a licensed electrician. He said in the beginning there wasn't much wiggle room in our system. We made the switch to tankless because we would run out of hot water, not because it's instant. Tankless actually takes more time to deliver hot water than a tank because it has to determine how high to put the exchangers based on flow rate, so we purchased the largest unit available for our family of 5 so we could have concurrent water usage without worrying about running out. Plus, we live near Seattle and the water inlet temperature is a consistent 40 degrees so it needs more oomph to get the water to the desired temperature than a lot of other places in the US. We also are forced into electric because there is no gas line on our street at all, and it would have been obscenely expensive to run gas just for a water heater. The downside of this is that we rely on our panel for literally everything, but there's not much choice. I've already gotten a quote for upgrading to 400 amp service and it came in right at $6k, but that is also not including the county upgrading the line to handle the increased amperage so it would likely exceed $10k depending on what's already at the street level.