Electrical systems must be grounded so that electricity can be harmlessly discharged into the earth. Grounding is an essential safety precaution to minimize shocks and prevent damage from lightning, short circuits and faulty wiring. Without grounding, the electricity is live and will transmit a charge to a person or object that comes in contact with it. This can result in an electrical fire or electrocution. The ground wire is the biggest electrical safety feature in a house. It services all of the electrical outlets and should also ground all of the light fixtures.

 How Do You Ground an Electrical System?

The most common way to ground an electrical system is by attaching the grounding wire to the cold water pipe. In order to ground an electrical system, all of the white neutral wires are connected in the main service panel to a metal strip called a neutral bus bar. A 100 amp service requires a bare #6 copper grounding wire which runs from the neutral bus bar to the metal cold water supply pipe that goes into the ground.  According to 2018 CEC 10.114, a 200 amp service calls for #6 CU (#4 AL) conductor for grounding conductor, and bonding 100A-200A (table 16). The wire is attached to the pipe with a ground clamp made of copper, bronze or brass. The copper grounding wire is bare because it has no need for insulation since it is already grounded. When the water supply pipe is plastic, the ground wire runs from the neutral bus bar to a pair of metal rods outside driven four feet into the ground. This is referred to as a double ground. It is quite common in older homes to find the grounding wire connected to a metallic copper or galvanized plumbing supply pipe that is close to the electrical panel. Under today’s standards it is to be connected before the first shut-off valve leading into the house.

Costs and Cautions

When a house needs an electrical upgrade or if the system needs to be grounded, a qualified electrician should do the work. It is important to ask for proof of certification from the province of Ontario. Electricians belong to the Hydro Authorization Program. A tag on the service panel indicates who did the electrical work, and verifies that it has been inspected and approved by Ontario Hydro. When plastic piping enters into the house with a 100 amp service, double ground rods are required connected by a continuous wire uncut. The cost of upgrading an electrical service from 60 amp to 100 amps starts at around $800.00 which includes permits.

That cost can increase depending on how far the incoming wires are from the main panel and how close the water pipe is to the main panel. In most situations grounding a 200 amp service simply involves adding a second ground clamp where the ground wire attaches to the water pipe.

A hydro inspection fee of $96.00 is required on any electrical work. This fee varies from one city to another.

About Receptacles

The most common type of outlet in older homes is the two-hole outlet, which can accommodate two separate plugs. This type of outlet is not grounded and cannot safely accommodate a three-pronged plug unless it is equipped with a properly installed grounding adapter.  Grounded receptacles were first introduced in the 1950’s. As the industrial revolution introduced new appliances and electrical technology, houses required larger electrical services. Overloaded receptacles caused power surges that blew fuses and tripped circuits. The grounded receptacle was introduced to prevent the failure of the entire system because of an overload on one receptacle.

New homes must be equipped with three-hole grounded receptacles. These receptacles have an opening for the grounding prong whereas the two-prong slots are different sizes. This is so that the plug can only be inserted the right way, ensuring proper polarization. Polarity is achieved when the hot and neutral wires of the power supply circuits are connected to the corresponding hot and neutral wires of an appliance.

Insurance Requirements

Many homes over 40 years old have a 60 amp service that uses knob and tube distribution wiring. Knob and tube wiring was the first type of electrical wiring used in homes. Though it may work, the insulation may be brittle and this type of wiring has no ground conductor. Most insurance companies will not insure a home that has a 60 amp service or knob and tube wiring. They will request a minimum upgrade of this wiring system in the basement where it is exposed.