Old-home electrical
Knob-and-tube wiring replacement
Knob-and-tube is the wiring many older houses were built with: individual wires on porcelain knobs, with no ground. We find out how much of it is still in use, and replace it in an order that makes sense for the house.
What it is
Knob-and-tube runs the hot and neutral as two separate wires, held away from the framing on porcelain knobs and passed through joists in porcelain tubes. There is no equipment ground. It was designed to shed heat into open air, which is why it matters when insulation has later been blown in around it.
What we check
- Which circuits are still knob-and-tube, and which were replaced.
- Splices where newer cable was tied into the old wire.
- Insulation packed around live runs in the attic or walls.
- What the circuits now feed, compared with what they were built for.
How replacement works
New grounded cable is run from the panel to each outlet, switch and fixture, and the old circuit is disconnected. In most houses the new wire goes in through the attic and crawl space with small wall openings where needed. The old wire is usually left in place, dead, where removing it would mean opening more wall. Where the panel is a fuse box or too small, it is replaced as part of the job; see panel upgrades.
VoltGen Energy operates under Akopi Builders, CSLB #1112420. Electrical work is performed by licensed C-10 electrical contractors. Check the license at CSLB.
What the price depends on
- How many circuits are still live knob-and-tube.
- How the house is framed, and how much of the route runs through the attic and crawl space.
- Whether the panel is a fuse box or too small and is replaced as part of the job.
You get a written estimate after a walk-through, before any work starts.
What to expect on cost: Knob and tube replacement cost in Los Angeles.
Also see old-home rewiring.
Questions we get
How do I know if my house has knob-and-tube?
Look in the attic or crawl space for single wires running on white porcelain knobs or passing through porcelain tubes in the framing. Two-prong outlets and a fuse box are hints but not proof. An evaluation confirms where it is and how much of it is still live.
Does it all have to come out at once?
No. Many houses have a mix: some knob-and-tube still in use, some already replaced, some abandoned in place. Circuits can be replaced in phases, starting with the ones that carry the heaviest loads or feed kitchens and baths.
Will you have to open the plaster?
Some openings are usually needed where framing blocks a route, but most new wire is pulled from the attic and crawl space. The estimate lists which walls get opened, and who repairs them, before work starts.
Is knob-and-tube dangerous?
Original knob-and-tube in good condition was a sound wiring method for its time. The problems come from age, from insulation packed around it, from splices added later, and from loads it was never meant to carry. That is why it is worth evaluating rather than guessing.
Talk it through before anyone opens a wall
Call with your address, the age of the house if you know it, and what you want to add or fix. We will tell you what the next step is.