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Electrical Wire and Cable

Upgrade Old Knob and Tube Electrical Wiring

Can I upgrade circuit wiring and outlets and still keep the lighting circuit in tack? How to Fix Old Electrical Wiring Problems: Guide for Repairing Old Wiring, Upgrading Knob and Tube Wiring and a Fuse Box

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Electrical Project: Can I upgrade circuit wiring and outlets and still keep the lighting circuit in tack?

My 1907 house has a 200 amp service, and the kitchen has been upgraded with new circuits.

Any help will be greatly appreciated!

Background: Rebecca, a Handy-woman from Jackson, MO.

Additional Comments: Thanks for your site, and thanks for your help!

Dave’s Reply:
Thanks for your electrical wiring question Rebeca.

home electrical rewiring

How to Fix Old Electrical Wiring Problems

Upgrading Knob and Tube Wiring and a Fuse Box

  1. Replacing the Fuse Box
    When upgrading the existing knob and tube style wiring it is important to disconnect the existing portion of the circuit that has been replaced with new wiring, and it is best to remove any old or abandoned wiring.
  2. Replacing the existing fuse box with a new sub-panel with circuit breakers would be advisable, and most likely necessary to eliminate the possibility of complications with fuses and connections within.
  3. The sub-panel must have a separate ground wire that is bonded back at the main electrical panel.
  4. The sub-panel ground wire must not be bonded with the neutral wire inside the sub-panel, the two must be separate and isolated from each other.
  5. The ground and neutral wires are only bonded together at the main electrical panel where the ground bond is required.
  6. While your at it, I would strongly suggest that consider installing smoke detectors in the home that are hard-wired with battery back up and inter-connected together so that if one goes into alarm, they all do.

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FAQs Frequently Asked Questions and Comments

2 Responses to “Upgrade Old Knob and Tube Electrical Wiring”
  1. Dave Rongey says:

    Hi Bob,
    The size of the wire or cable would depend on the size of the panel that would be installed, and this can only be determined by knowing what the load will actually be. If you are just replacing the bedroom circuits as mentioned then the actual loads of these circuits will need to be evaluated. The loads should also take into consideration all appliances that are plugged in during the year, including space heaters and room air conditioners. Also consider any additional loads or dedicated circuits that may be added. After this is known then the panel size and cable size may be determined.

  2. Bob says:


    I was told that pulling a wire for a sub panel would be the best way to get power above the rooms that presently have knob and tube wiring. I need to know how do I determine what size wire to buy for this run. I have a Cutler Hammer 100 amp CH7 and 4 of the breakers, one 20 amp and three 15 amp are wired with knob and tube. The local inspector said that I could leave the knob and tube and that there isn’t any reason to install Romex unless I really want to.