As noted in the first part of this series of articles on Knob & Tube wiring many issues come to the forefront when dealing with this type of wiring. In understanding what can or needs to be done we need to determine if and what the Electrical Safety Authority of Ontario (ESA) has to say to the issue. The ESA has the government mandated authority for electrical safety in our province of Ontario. Their website has pages of information relating to electrical safety and is worth a visit if you have a moment. http://www.esasafe.com/ . ESA has some very specific criteria in regards to Knob & Tube wiring and its safety. The following is a bulletin by ESA stating their position on the issue of Knob & Tube

BULLETIN		12-27-2

 

Knob and Tube Wiring in Residential Installations

Rule 12-200

 

Since January 2003 the Electrical Safety Authority has received an increasing number of questions about the safety of knob and tube wiring.  In particular, purchasers or owners of older homes are finding that many insurers will not provide or renew coverage on such properties. In some cases, the insurance companies are requiring a total replacement of this wiring prior to providing insurance coverage.

 

Knob and tube wiring, more recently referred to as open wiring, was a wiring method used in the early 1900s to 1940s in the residential sector. Over the years wiring installation practices have changed in the residential sector and knob and tube wiring is no longer installed; however, parts continue to be available for maintenance purposes.

Existing knob and tube conductors concealed in walls, floor spaces, etc; supplying general lighting and receptacle circuits are permitted to remain in place if:

 

• They are protected by a 15 ampere fuse or circuit breaker; and
• No additional outlets have been added to the original installation so as to overload the circuit; and
• The conductors, where visible, appear to be in good condition.

 If your home has knob and tube wiring, we recommend that you follow these guidelines:

 Have a qualified electrical contractor check the “knob and tube” conductors in your existing installations for sign of deterioration and damage; or request a general inspection from ESA.  The General Inspection report will identify visible electrical safety concerns in your electrical wiring.

• “Knob & tube” conductors should be replaced where exposed conductors show evidence of mechanical abuse and or deterioration, poor connections, overheating, alterations that result in overloading, or if changes to wiring contravene any section of the Ontario Electrical Safety Code.

 Homes with knob and tube wiring may not have the electrical capacity to meet today’s needs.  As a result, homeowners have modified their electrical system with what the Electrical Safety Authority classifies as unsafe practices: 

 

• Improper use of extension cords – using improperly rated extension cords, or using extension cords as permanent wiring;
• Improper fuse replacement – using 20 or 30 amp fuses to replace15 amp;
• Improper connections - adding receptacles and outlets on existing circuits or improperly connecting to the knob and tube wiring (this work should be done by a qualified electrician);
• Removing ground pins – ground pins on power bars or electrical equipment should not be removed to accommodate the two pin receptacles used in knob and tube wiring. (2 pin to 3 pin are not permitted)

 

Improper replacement of two pin receptacles. If you require a three prong receptacle, only use a GFCI receptacle.

 

 

Where grounding type receptacles (three pin) are installed in existing knob and tube installations to replace the ungrounded type (two pin) receptacle, special caution must be exercised.

 

Rule 26-700(7) requires the installation of a bond conductor to bond the receptacle to ground. This is permitted to be an external bonding conductor that is connected to either the system ground conductor or a metallic cold water pipe that is bonded to ground.  This method may be difficult to accomplish.

 

As an alternative to bonding the Code also states "grounding type receptacles without a bonding conductor shall be permitted to be installed provided each receptacle is protected by a ground fault circuit interrupter of the Class A type that is an integral part of this receptacle; or supplied from a receptacle containing a ground fault circuit interrupter of the Class A type; or supplied from a circuit protected by a ground fault circuit interrupter of the Class A type (a GFCI breaker in the panel, or either a GFCI receptacle or a GFCI dead front mounted in an outlet box next to the panel).

 

Where this option is used, no bonding conductor is permitted between outlets unless that bond conductor is in turn connected to ground.

 

GFCI protection of the receptacles does not provide a ground reference to the U-ground slot of the receptacles. Some appliances require a bond be connected to the U-ground slot in order to function properly. For example, surge protective devices for computer or entertainment equipment will not function without a ground reference.

 

As new electrical equipment is introduced into the dwelling unit there might be a need for additional outlets to be installed. Extension cords are not to be used as a substitute for permanent wiring.  The following shall be followed when installing new receptacles:

 

• Outdoor receptacles shall be GFCI protected,
• Bathroom and washroom receptacles shall be GFCI protected.
• Kitchen receptacles within 1 meter of a sink shall be GFCI protected
• New outlets shall follow the current Ontario Electrical Safety Code requirements for wiring, meaning a new branch circuit shall be grounded and receptacles that utilize the three pin grounded configuration.

 

While knob and tube conductors in good condition and has not been inappropriately altered will not present undue hazards it is worth noting that modern electrical installations contain safety benefits not found in older electrical systems. These include:

 

• Generally larger electrical capacity and more electrical circuits reducing the need to use extension cords
• Splices and joints made in approved electrical boxes
• Dedicated electrical circuits for certain types of electrical equipment or appliances
• Grounded and bonded receptacles, switches and light fixtures
• Ground fault circuit interrupters in bathrooms and outdoor locations, and with the latest edition of the Ontario Electrical Safety Code
• Arc Fault Circuit Interrupters in bedroom receptacle circuits
• And GFCIs near kitchen sinks.

 

Homeowners who are planning to modify their knob and tube wiring, or any other electrical wiring, should have the work performed by a licensed electrical contractor or electrician and arrange for an electrical inspection by Electrical Safety Authority.

 

    To put the ESA's rules into practice the following should be noted-

1. Though still legal in existing situations new installations inside residential buildings are not used or allowed. The above criteria are for wiring already in place.

2. The insulation of the conductors needs to be in good condition were it can be readily seen and inspected. This means flexable and insulation in place around the individual conductors. Often the  insulation can become brittle and frayed and no longer covers the conductor providing no protection from shock if you should accidently contact a live wire.

3. The circuit has not been modified by adding more lights, and receptacles to the wiring circuit.

4. If the circuit has been added to, many times this can lead to the third criteria being broken which is that the fuse or breaker protecting the wiring must be a naximum of 15 amps. This is usually more of a problem with older style fuse boxes. If the Knob & Tube circuit has been added to then more load is added which can cause the protecting device, fuse or breaker, to fail or trip. This is exactly what they were designed to do. With the breaker you reset it and try to not over load the circuit by turning on to many items at once or switching some appliances or lights etc to another circuit. Often though if fuses are the means of protection then a 20 or 30 amp fuse can be used as a replacement for the proper 15 amp fuse. This is an extreamly dangerous situation as this can lead to fire and possible loss of property or life.

5. The other safety issue as noted in the ESA bulletin is tha there are no bond conductors present on any of the circuits. Bonding is one of the ways that electrical instalations have been made safer over the years. The real issue becomes when some one thinks that they are protected because they are on a bonded circuit but are not. The most common situation of this is plugging a 3 prong plug into a 3 pronged receptacle that was used to replace a older 2 pronged receptacle. This can lead to serious injury or death and sould be delt with promptly if discovered.

The next article in this series about Knob & Tube will deal with how to determine if you have this type of open wiring in your house.