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Household Electrical Circuits 110 Volt and 220 Volt

Understanding Electrical Circuits and Standard Household Voltages

When discussing any type of electric heat you are generally dealing with high voltage and care must be taken to avoid working with high voltage appliances while they are energized. Always turn off the power and always check for voltage with an appropriate electrical meter to be sure all power is off.

Another note is that you may be dealing with more than one power circuit for an electric furnace so be sure to check everything. The electric furnace is supplied with 220 volt AC to power the electric heating elements inside the furnace. On most electric furnaces this also powers the blower motor. 220 Volt AC is best described as two 110 Volt circuits utilized together or combined to provide a higher voltage. Most electric driers, stoves and water heaters are powered using 220 Volt circuits.

Like all electrical systems the basic thing to understand is that the circuit must be complete in order for the electricity to flow and do work. A simple example would be a standard light bulb which we all understand as having a filament inside that heats up and glows when energized with power and when the filament breaks the light bulb no longer works. Electrical circuits are exactly the same, if any part of the circuit is broken the electrical power ceases to flow. Hence that is exactly what a light switch does, it breaks the circuit (also called an open circuit) so electricity cannot flow to the light bulb.

On standard 110 volt circuits this completed circuit (also called a closed circuit) is from the hot wire (normally black or red) through to the neutral or common wire (normally white) and to check this circuit you would read or check the resistance of the circuit with a multimeter from the hot side to the neutral side. The 220 Volt circuit is different in that the this is no longer true, the two 110 volt hot circuits (normally black and red) are combined to make 220 volts and the circuit is completed (again a closed circuit) when the two separate 110 Volt circuits are complete, no neutral ever really comes into play. So in this case you would be reading or checking the circuit through the two separate hot sides of the circuit.

WARNING: Electricity is dangerous and can cause serious injury or death, always assume electrical power is on unless you have checked it with an appropriate meter. Never work on live electrical wires always turn off the power at the circuit breaker. Ameri-Serv, Inc. assumes no liability for the use of the information provided on this website.