Knob-and-Tube Wiring

Knob and tube wiring is an outdated electrical system still hidden in many older San Francisco homes. This ultimate guide explains what it is, how it works, why it’s considered risky today, and what homeowners should know about safety, insurance, and planning a professional rewiring.

Knob and tube wiring is common in many of San Francisco’s historic homes — but this outdated system poses serious safety and insurance risks. Replacing it can cost anywhere from $10,000 to $30,000+, depending on the home’s size, layout, and accessibility. In this guide, we break down what affects the total price, how the rewiring process works, and why investing in a modern electrical system is one of the smartest upgrades for your San Francisco home.

San Francisco’s iconic housing stock — Victorian, Edwardian, and pre-war homes — carries a certain charm that continues to attract buyers from all over the world. But alongside the bay windows, ornate staircases, and original woodwork, there often hides a serious problem: knob-and-tube (K&T) wiring. While some owners view this early electrical system as a

Just found out your house has knob-and-tube wiring? Don’t panic—this friendly guide explains what it means, when you should replace it, and how to handle it without losing your mind (or your historic charm).