Knob-and-tube wiring
What knob-and-tube is, and what to do about it
It is the wiring most Providence houses had before about 1940, and many still do.
Two single wires run apart from each other, held off the framing on porcelain knobs and passed through joists and studs in porcelain tubes. There is no ground wire. In open attics it can stay sound for a long time. Behind plaster, under insulation, or spliced into newer cable, it needs a closer look.
What it looks like
Single wires in pairs, spaced apart on white porcelain knobs
Porcelain tubes where the wire passes through framing
Cloth-wrapped, rubber-coated wire and no ground wire
Often found beside newer cable in the same wall
From the owner
Carmine at an open wall
Where the wire runs, how to tell old from new, and what he would ask any electrician before signing.
Knob-and-tube wiring at an open wall
Carmine Palumbo, owner and master electrician
Cost drivers
What decides the price of a knob-and-tube rewire
We give no price here because two houses of the same size can differ by a lot. These are the reasons.
Access
An open attic and basement make runs short. Finished plaster means longer fishing and more patching.
How many circuits
Every room, floor and appliance that has its own line adds work. The survey counts them.
What is behind the wall
Mixed wiring, buried splices and insulation around old wire take time to trace.
The panel and service
A fuse box or a small service usually changes with the rewire, and that is a separate line on the estimate.
Permit and inspection
Fees are set by the city or town and passed through at cost.
Patch and paint
We patch the holes we make. Skim coats, paint and wallpaper are not in the estimate.
Questions
Insurance, rebates and the rest
Short answers for the questions that come up most. Your survey will cover your house.
Is knob-and-tube dangerous?
It was safe when installed, in open air with room around each wire. Age, insulation packed around it and later splices are the problem. The survey separates the runs that are a risk from the ones that are only old.
When is it urgent?
Burning smell, sparks, a hot or scorched outlet or panel, water near wiring, or shocks. For fire, call 911. If it is safe to reach, turn off the breaker, then call us.
Will my insurer care?
Some insurers ask about wiring age before they write or renew a policy, and some ask for proof of work done. Ask yours what it needs. We can describe the work, its date and the permit in writing, and we can't speak for your insurer.
Will my insurance cover the work?
Almost never. A rewire is an upgrade, not a loss. Ask your agent about your own policy.
Are there rebates?
Programs change, and we don't promise one. Some utility programs ask that knob-and-tube be dealt with before insulation goes in. Ask Rhode Island Energy what is open now, and tell us the program name so the estimate lines up with its rules.
Do I need a permit?
Rewiring needs one, and we pull it. The inspector comes after the work and before we patch.
How long will it take?
The estimate gives a schedule, floor by floor. A house with an open attic goes faster than one with finished plaster on every floor.
Can you rewire only part of the house?
Yes. A common plan is the kitchen, bath and any room with insulation going in, with the rest later. We write the plan so the later work joins up.
Find out what is in your walls
A survey maps the old wire and ends with a written estimate, room by room.