Knob-and-Tube Wiring in Los Angeles: Risks & Replacement

Plenty of charming older homes in Los Angeles — especially in neighborhoods like Pasadena, Highland Park, and Eagle Rock — still have their original knob-and-tube wiring. It was standard from the early 1900s into the 1940s, but it wasn’t built for the way we use electricity today. If your home has it, here’s what you should know.

What Is Knob-and-Tube Wiring?

Knob-and-tube (K&T) is an early wiring method that runs individual conductors through ceramic knobs and tubes, with no protective ground wire. You can sometimes spot it in an attic or basement as single cloth-covered wires held off the framing by white ceramic knobs.

Why It’s a Concern Today

• No ground wire. Modern appliances and electronics expect a grounded, three-prong system K&T doesn’t provide.
• Brittle insulation. After decades, the cloth/rubber insulation dries out and cracks, exposing live conductors.
• It wasn’t built for modern loads. Today’s homes draw far more power, and overloaded K&T can overheat.
• Insulation problems. Burying K&T in modern blown-in insulation traps heat — a known fire risk.
• Insurance and resale. Many insurers won’t cover homes with active K&T, and it routinely comes up during home sales.

Do You Have Knob-and-Tube?

Look for single cloth-covered wires on white ceramic knobs in the attic or crawl space, two-prong outlets throughout, and no ground wires at the panel. The safest way to confirm is a professional inspection — there are live, ungrounded conductors involved.

Replacing Knob-and-Tube Wiring

The fix is to replace K&T with modern grounded wiring — sometimes a few circuits, sometimes a whole-home rewire. It’s usually done alongside a panel upgrade so the whole system is safe and up to code. A licensed electrician will pull permits, handle inspection, and make sure nothing is left energized.

If you’re seeing the signs of old wiring, our whole-house rewiring guide walks through the process and what affects cost.

Get a Knob-and-Tube Assessment in Los Angeles

911 Construction & Electric is a licensed, bonded, and insured electrical contractor (CA Lic. #1027421) serving Los Angeles and nearby cities. Contact us for a free assessment or call 747-255-8595 — we’ll confirm what you have and lay out your options.