Wiring in Historic and Older Homes

Historic and older homes come with charm and wiring questions.

Historic homes come with charm and a lot of questions about wiring.

Older homes come with a great deal of charm and style, as well as a number of potentially hazardous situations related to old wiring.
Old house electrical systems can often become a rat’s nest of wires and splices as the occupant’s electrical needs have grown over the years and unqualified people have worked on the wiring.

Depending on the age of your old house, you may have several generations of electrical wiring and components that aren’t as safe as they should or could be.

Knowing the Condition of Your House’s Wiring

In order to determine if your historic house or building requires new electrical wiring or needs upgrades, a qualified electrician will need to conduct a thorough inspection of the electrical system.  As an electrical contractor who has worked on a great many historic one-of-a-kind properties we understand that it takes a very specific set of skills to do this work well.  Even then you have to love these properties like they are your own and believe in their value!  See our thoughts on how to proceed with your older home.

Not All Old Wiring Is Unsafe
In unaltered buildings built since about 1940, the electrical system can be intact and safe – but there are a lot of *IF’s* with that statement. These homes used a variety of electrical wire types with different forms of insulation and since 1940 there have been many changes to the NEC (National Electrical Code).  You will want to check to make sure there are enough existing circuits and the load capacity is adequate for the electrical requirements of the renovated home or building.  It is also important to understand if the wiring is grounded and was installed correctly initially.

Watch Out for Knob & Tube Wiring
As you are inspecting the electrical wiring in your house or building, you should determine if your structure has any knob and tube wiring.  This was the earliest form of electrical wiring in the U.S. and was used in the 1870’s to the 1930’s.  The popularity of knob and tube wiring diminished by 1940, but continued to be installed in some homes and buildings until about 1975.

Knob and tube wiring consists of two wires running parallel to each other and threaded through a hole in the joist. A porcelain tube inserted into the hole prevents the wire from touching the wood. When these wires are bent to make a turn, they are wrapped around a porcelain knob nailed to the side of the joist. Since knob and tube wiring has no grounding wire, it can be a fire and shock hazard. If you find knob and tube wiring during your inspection, it would be our only recommendation that it needs to be replaced.

Requirements for GFCI Outlets
If you are planning a substantial rehab to your structure, you might be required by building codes to install a three-pronged, grounded GRCI outlet every six feet.  A licensed electrician can help you determine if you must meet this requirement.

Outlets within six feet of every sink or water-supplied fixture should be GFCI (ground fault circuit interrupter) outlets. A GFCI outlet has a push-in button for testing and another button that acts like a circuit breaker. A GFCI outlet, and any outlet that is properly wired to it, will prevent an electrical short caused by water coming in contact with a source of electricity.

Check Your Light Fixture Wiring
If the wiring to your lighting has only two wires present, it is a good indication that your lights are not grounded. This can create a fire and shock hazard and the ceiling light fixtures in your house or building will need to be rewired.

Need Someone to Inspect Your Wiring?
Please note that the information presented in this article is not intended to provide comprehensive technical advice or instructions on solving historic home wiring issues.
If you have questions or need someone to inspect your historic home’s wiring, one of Artisan’s experienced electrical technicians will be happy to arrange a time to stop by. Just give us a call at 765-414-3913.