Fatter is Better for Long Electrical Wiring Runs

January 2004

Eliminate "Voltage Drop" Problems in Your Home

When your home was built, an electrician estimated how much electricity would be used in the various rooms and typically sized the wires to the minimum requirements of the electrical code for outlets and lighting. It wasn't very long ago when 100-amp service, and even 60-amp service, was considered adequate, and relatively few wiring runs and outlets were installed to serve the entire home. Even today, it's not unusual to find one branch circuit serving many outlets in many rooms of a house.

Times have changed, however, and home electrical consumption has skyrocketed. If your home hasn't been rewired since it was built, you may experience "voltage drops" when power use temporarily exceeds your electrical system's capacity - and these can severely affect the life and performance of appliances, tools, toys and electronic systems.

A voltage drop occurs between the electricity's point-of-origin - typically a transformer outside the home - and its point-of-use, and it's caused by the resistance in the wiring and other electrical conductors along the way. Voltage drop is comparable to a drop in pressure in a garden hose when it's too long.

Electricity flow is measured in amperes (amps for short) of current. Basically, the farther the current (electricity) travels, or the smaller the diameter of the wire, the greater the voltage drop. Also, the voltage drop increases as more current is drawn.

When this voltage drop is excessive, or when it occurs on top of a brownout, a voltage reduction or marginal voltage at the service, it can damage electronic circuits, dim lighting, and cause electric motors and appliances to run slow or overheat.

Upsize Wiring or Add Circuits

One remedy for voltage drop is to upsize your home's wiring. Thicker copper wires offer less electrical resistance. That means replacing 14-gage wires with 12-gage wires, or replacing 12-gage wires with 10-gage wires. In wiring, "gage" equals diameter, and lower gage numbers designate larger wires. Another remedy is to run additional branch circuits, so the load on each is lessened. Adding branches is often preferred in home offices or other areas with a lot of electronics. An electrician can easily calculate voltage drop at different points throughout your home and run new wiring or install additional lines and outlets to relieve the problem.

Voltage drop doesn't affect all homes, but it frequently occurs in larger houses or ranch-style homes with long wiring runs, and in older homes with undersized wiring or very long runs. Electronic equipment is particularly sensitive to voltage, so if your home office or entertainment center is a long way from your electrical panel, or too many electrical devices share the same circuit, it could be a problem.

Voltage drop also can be a hazard where inadequately sized extension cords are used. Extension cords need to be sized according to the manufacturer's amperage and distance recommendations for indoor or outdoor use. Homeowners with backup electric generators also must carefully size the power cords that carry electricity into the home. Fatter wires are better - 10 gage or heavier depending on the generator's capacity - to protect against voltage drops.

Call an Electrician

If you have any doubts about the power quality provided at the outlets in your home, the best advice is to call in an electrician. You can get an estimate for upsizing the wiring or adding circuits to heavily used areas of your home, and then say goodbye to those voltage drop blues.

You can also visit our Building Wire section for more information about residential electrical wiring.