House has old knob-and-tube wiring

Symptoms

• Visible ceramic knobs and tubes in an attic or basement with cloth-covered wire
• No ground wire present at outlets on these circuits
• Insurance company asking about wiring type

Likely causes

• CommonOriginal wiring never replaced since the home was builtMany older homes still have some or all of their original knob-and-tube circuits.
• PossibleInsulation added over knob-and-tube wiring, which isn't rated for itModern insulation placed over these circuits can trap heat and is a recognized fire risk.
• PossibleSplices or modifications made without proper junction boxesDIY additions to old wiring sometimes weren't done to code.

What to do

1. Do not add or blow in insulation over any area with knob-and-tube wiring without addressing the wiring first.
2. Avoid connecting knob-and-tube circuits to modern high-draw devices, dimmers, or many smart switches.
3. Check with your insurance company, since some companies require this wiring to be replaced or won't insure homes that still have it.
4. Have an electrician inspect the extent and condition of any knob-and-tube wiring still in use.
5. Prioritize rewiring circuits that show damage, have been spliced improperly, or are covered by insulation.
6. Budget for a full rewire if you plan major renovations or additions, since it's often required by code at that point.
7. Never attempt to repair or extend knob-and-tube wiring yourself.

When to call a pro

Have a licensed electrician evaluate any home with knob-and-tube wiring, especially before insulating, renovating, or adding major appliances.

Safety