08/12/2026
Getting quotes for a heat pump or mini-split and someone mentions your electrical panel might need an upgrade?
A lot of San Francisco and Marin homes, especially anything built between the 1950s and 1980s, were wired for 100-amp electrical service. That was plenty for a house with gas heat and a handful of standard appliances. It wasn't sized with a heat pump in mind.
Here's what actually matters: the panel's age alone doesn't tell you whether you need an upgrade. What matters is a real electrical load calculation, done by a licensed electrician, that looks at what your home is already using and what the new equipment would add. Some 100-amp homes have plenty of room left. Others don't. There's no way to know which one you are without the math.
If you're weighing a heat pump or mini-split, it's worth asking upfront whether a load calculation has actually been done, or whether "you'll probably need a panel upgrade" is just an assumption based on your panel's age. Those are two very different conversations, and you deserve the one based on the numbers.