4. Accommodating the Electrical Load

If you are planning to heat with electricity, it may be necessary to upgrade or adjust your home's electric service in order to cope with the additional load. Two basic approaches are described in this chapter.

Electrical Service Panels

Usually, a house that is not heated by electricity has a 60A or 100A electrical service output. To install an electric heating system, you may perhaps need to upgrade your home's electric service to 200A or more.

To do this, you should replace:

the electrical service panel (fuse box or breaker panel)
the three heavy wires that supply electricity to your home and their housing
the meter base and receptacle

Figure 14: Typical electric service installation

Typical electric service installation

If you are building a new house, consider installing a 200A service for whatever type of heating system you choose. This could avoid costly service upgrading in the future. In general, a representative from your electric utility can evaluate your consumption of electricity and future needs, and take the final decision regarding your home's required electric service.

Your local electrical utility representative should be consulted before any work begins. Either you or your electrical contractor must obtain a permit from the appropriate authority before any alteration to wiring is undertaken. Some utilities also provide precise information on the cost and installation of a new electric system. The installation must be inspected upon completion.

Load Management Devices

Equipment is now available to manage the extra load placed on a standard (100A) electric service when an electric heating system is added to a household. These load management devices are compatible with any electric heating system, but are used mostly when plenum heaters are added to an oil furnace. A sensor on the wires supplying electricity to the house monitor the amount of electricity used.

If the amount of electricity used in the house is heavy–say when the water heater, the stove and dryer are all in operation at the same time–the device restricts the amount of current allowed to reach the heating elements of the heating system. This prevents an overloaded demand on the house's electricity supply. In oil furnaces using plenum heaters, the load monitor compensates for an increased household demand by temporarily switching off one or more of the plenum heater's elements. Then, as appliances are turned off, the sensor responds by allowing more electricity to flow to the heating system (or by switching the plenum heater's elements back on) up to the full capacity allowed. Except for water heaters and dryers, nearly all the electricity used by household appliances ends up as heat–which compensates somewhat for the slightly lower output by the heating system.

Load monitors may eliminate the need for upgrading to a 200A service. In some provinces, however, electrical utilities may find these devices unacceptable. Check with your electrical utility if you are considering using this kind of equipment.

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Source: Natural Resources Canada (NRCan) - Office of Energy Efficiency