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Wiring codes and there origin

    Wiring codes are intended to protect people from electrical shock and fire hazards .The very first electrical codes started in 1881 in New York to regulate the installations of electrical lighting. Since 1927 , the Canadian Standards Association also know as ( CSA ) has produced the (Canadian Safety Standards for Electrical Installations ) which became the basis for all provincial electrical codes.

    The Canadian and the U.S. National standards differ occasionally in technical detail however they deal with the same physical phenomena and have similar objectives. As part of the North American Free Trade Agreement (NAFTA) program, U.S. and Canadian standards are slowly converging toward each other, in a process known as harmonization.

The difference between electrical insulators and conductors

     In many materials, the electrons are tightly bound to the atoms. Wood, glass, plastic, ceramic, air, cotton -- these are all examples of materials in which electrons stick with their atoms. Because the electrons don't move, these materials can't conduct electricity very well, if at all. These materials are  electrical insulators..

    Most metals, however, have electrons that can detach from their atoms and zip around. These are called free electrons . The loose electrons make it easy for electricity to flow through these materials, so they're known as electrical conductors . They conduct electricity. The moving electrons transmit electrical energy from one point to another.

How circuit breakers/fuses work

    Circuit breakers ( or the alternative , fuses )  may be one of the most important safety devices in your home. Whenever the wiring in your home or building has too much current flowing through it these devices cut the power until the problem can be fixed. Without these devices the potential for fires and other accidents resulting from simple wiring problems or equipment failures would be huge. The problem with fuses is they only work once . When you blow a fuse, it burns up the wire inside the fuse and you have to replace it with a new one. A circuit breaker on the other hand , closes the circuit when the current climbs to unsafe levels, but it can be reset and used over and over again.

GFCI  ( Ground Fault  Circuit Interrupter )

    GFCI receptacles were designed to protect you from electrical shock. A GFCI monitors the amount of current flowing from the hot wire to the neutral wire.  If the receptacle detects any imbalance in the current , it trips the circuit. They are designed to react as quickly as one-thirtieth of a second and can sense a mismatch as small as 5 milliamps.  Building codes are now requiring that receptacles in potentially wet areas ( IE. Around bathroom/kitchen sinks or outside ) be GFCI protected for safety reasons. So let's say you are outside with your power saw and it is raining. You are standing on the ground, and since the saw is wet there is a path from the hot wire inside the saw through you to the ground . If electricity flows from hot to the ground through you, it could be fatal. The GFCI can sense the imbalance in the current because not all of the current is flowing from hot to neutral as it expects -- some of it is flowing through you to the ground. As soon as the GFCI senses that, it trips the circuit and cuts off the electricity.

Aluminium wiring

    Aluminium wiring became popular in North America from the late 60's to the mid 70's due to the rising cost of copper. Aluminium wiring requires a lager conductor than copper due to the fact that it has greater resistance. For example , on a typical 15 amp circuit you would use a 14 gauge copper wire ( used for most lighting circuits ) where you would need a 12 gauge aluminium wire although local building codes may vary. Aluminium conductors were originally used with wiring devices intended for copper wires. This could cause defective connections unless the devices were designed to address problems in joining dissimilar metals.

    Because of improper installation and design, some of the wiring junctions overheated under heavy current load and caused fires. Revised standards were designed to reduce these problems nonetheless aluminium wiring for residential applications has acquired a bad reputation and is no longer in use. Aluminium conductors are still used for power distribution and large feeder circuits, because they cost less than copper wiring, and weigh less, especially in the large sizes needed for heavy current loads. Aluminium conductors must be installed with compatible connectors.

Nathan Pile
Barrie Home Inspector

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