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Knob and Tube wiring


What is
"Knob & Tube" Wiring?

Knob & tube wiring was used in most residential construction until the early 1950's. This wiring gets its name from the ceramic knobs to which the wires are secured and the ceramic tubes in which the wires pass through the wood framing.

There are several differences between this type of wiring and current (post 1960) wiring, such as:

The Regulations in B.C.

The regulatory authority for residential wiring in British Columbia is the Electrical Safety Branch. Since "knob & tube" wiring is no longer part of the Electrical Code, it is considered old building technology. It is not necessary to replace it as a matter of course and there are no written bulletins or directives on this matter. There is, however, a requirement that the complete circuit must be upgraded to current standards if any part of it is modified.

Insurance Concerns

The insurance industry appears to be taking a more aggressive approach. Insurers regard this older wiring to be an increased hazard and often refuse to provide insurance even on houses that have been substantially but not completely rewired. This is a concern because the insurer may require that a relatively small amount of the "knob & Tube" wiring be completely replaced in spite of the fact that the older house has been mostly rewired and is "reasonably" safe.

Last updated October 25, 2010

DISCLAIMER: Please note that the information and materials located on our web site is provided free, for general information only, and is not intended to provide or be relied upon as specific professional advice. This information represents the current technical facts as understood at the time published, but is in no way comprehensive and you should not act or rely on it regarding your specific situation -- until you have consulted with a qualified home inspector. No liability is accepted therefore for any errors or losses that may be incurred if it is relied on "as is". The use of information posted on these pages does not create a consultant-client relationship.