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Electric Service and
Electric Wiring

Insight and understanding that only a Licensed Engineer can provide
Over 80,000 inspections performed since 1968

A modern house or building requires electricity to run many of its vital systems such as lighting, heating, hot water, appliances, and air-conditioning.  Because so many of today’s appliances require electric power, some existing buildings do not have enough circuits to support the demands of modern electrical usage.  Buildings with insufficient electric service need not be very old.  Even a home built only 10 years ago may not have the electric wiring to support the today's needs.

  Electric service insufficiency is often aggravated by homeowners who add appliances without properly upgrading the electric wiring.  Even changing an electric oven to a self-cleaning electric oven may increase the electric loads to the point where the electric service needs to be upgraded.  If a homeowner adds appliances without upgrading the electric service, a hazardous condition may exist.  In addition to advising you of the hazards, Heimer Engineering provides a written cost analysis in the narrative engineering reports.

Insufficient Electric Service

There is a misconception that if a house has circuit breakers and has 100 amp, 220 volt service, the electric service is sufficient.  There is also a misconception that if a house has circuit breakers (and no fuses), that the electric service and electric wiring are sufficient.  If a house has large electrical loads such as air-conditioning or an appliance such as an electric range, then 200 amp service may be required.

You can depend upon a Licensed Professional Engineers to assess the sufficiency of the electric service and electric wiring in your building.

Aluminum Wiring

Houses and buildings built between 1965 and 1973 may have been wired with aluminum wiring,  a potential fire hazard.  If you are planning the purchase of a house or building with aluminum wiring, obtain a copy of REPAIRING ALUMINUM WIRING by visiting the U.S. Consumer Product Safety Commission web site.

Definition of Electrical Terms

  Here are many terms used in describing home and building wiring.  Some of terms are often misused.  The following chart should help you understand the terms used to describe wiring and their meanings:

• Alternating Current (AC):  An electric current that reverses direction in a circuit at regular intervals.  Alternating current, also called AC, is used in almost all homes and buildings today.
• Amps:  The unit of measure of the flow rate of current.
• Circuit Breaker:  A device that shuts of a circuit by mechanical action when too much current is flowing.  When a high current passes through a circuit breaker a trigger rapidly separates a pair of internal contacts.  Unlike a fuse which must be replaced after it has blown once, a circuit breaker can be reset after it has been tripped.  Circuit breakers have replaced fuses in modern buildings.
• Circuit Breaker Panel:  An electric panel containing circuit breakers.
• Conductor:  A substance, typically metal, that conducts an electric current.  Copper and aluminum are the most common conductors in building wiring.
• Current:  The rate of flow of electrons, measured in amps.  The more electrons flowing, the more energy that is available.  However, the flowing electrons heat up the wire.  Too much heating of the wire creates a fire hazard.
• Direct Current (DC):  An electric current that flows in one direction in a circuit.   Direct current, also called DC, is rarely used homes and buildings today.
• Fuse:  A safety device used to protect against excessive current.  A fuse consists of a metal alloy strip with a low melting point.  Because of its electrical resistance, the alloy strip is heated by electric current.  If the current exceeds a safe value, the strip melts and stops the current.   Fuses are rarely seen in modern wiring.
• Insulation:  A material that does not conduct electricity.  A conductor wrapped in insulation forms the wiring found in homes and buildings.  Most modern insulators are plastic or vinyl.
• Power:  As a first order approximation, power is the product of the voltage times the current.  Power is a measure of how much work can be done in a certain period of time.  It is power (not voltage or current) that defines how much work is actually done.
• Sub-Panel:  An additional electrical panel installed after the main circuit breaker panel.
• Three-Phase Power:  Electrical power delivered in three separate phases.  This is the way electrical power is distributed throughout the community and supplied to buildings.
• Voltage:  The electrical energy available, measured in volts.
• Volts:  The unit of measure of electrical potential.
• Watt:  A unit of measure of electric power.
• Wire:  A conductor surrounded by an insulator.  Wires carry the electric current throughout a building.

Call 800.640.8090 or use the online form 24/7 for more information.

Call 800.640.8090, or click here to contact Heimer Engineering 24/7.

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This page was last reviewed on February 26, 2008.
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