Knob and tube was the standard way to wire homes for decades before the 1950s, and plenty of older Bay Area homes still have some. You can often spot it in an attic or crawl space: single wires running on white ceramic knobs and passing through the framing in ceramic tubes.
Why it matters now
- It has no ground wire, so it cannot safely serve three-prong outlets.
- The original insulation gets brittle with age and can crack where it has been disturbed.
- It was designed to shed heat into open air, so insulation packed around it can trap that heat.
- It was built for far less load than a modern home uses.
Insurance and selling
Many insurers ask about knob and tube, and some will not write a policy until it has been inspected or replaced. Buyers and their inspectors ask about it too.
Your options
It starts with an inspection to find out how much is left and what shape it is in. Sometimes that means replacing a few circuits. In other homes a full rewire makes more sense. Either way you get a free written estimate first, and the work is permitted and inspected.
Think you have knob and tube? Call or text us and we will take a look.