"I have old wiring-- do I need to replace it?"
Column #883 02/11/12
On The Level
Q. Weíve lived in our home for 42 years. It was three years old when we bought it. It started out as a 1967 all electric home and is served by a 200 amp panel. The wiring is all copper and we have a certificate showing that the electrical contractor that did the wiring won an award for the job they did. The only thing we have done to the system is install several three pronged outlets in different rooms in the house. We have electric baseboard heat for approximately 1600 square feet of living space, all on one floor.
Considering the age of the house should we re-wire and what would be the approximate cost to do it? I donít want to kick a sleeping dog but I donít want to burn down the house either.
A. Your home was built to be the most modern thing on the block back in the day when electricity was cheap.
The wiring and methods used at your house were ďstate of the artĒ and that being said I am confident that the wiring behind your walls is in good shape. Itís second generation Romexģ flexible cable and was inspected by an electrical inspector when it went in. Because the builder was going for the upgraded electrical certification, Iím sure the electrician doing the job took pride in his work and that made the job better. With 200 amps to the house, you have the size service that is still being put in houses the size of yours even to this day.
If you want to confirm what is going on you can have the face of the panel box-- called the deadfront-- taken off and all of the connections examined. What would be searched for would be signs of overheating at the connections, water damage or anything that may have been done since installation that is out of the ordinary. Notice I didnít say ďout of codeĒ. The electrical code is updated every three years and the code that your house was built under was pre-1970. I can tell that because you said youíve added three pronged outlets (grounded). They came into the code in the 1960s and not all house locations required them then.
Many safety innovations have been incorporated into the electrical code since your house was built such as smoke detectors and ground-fault circuit interrupters (GFCIs) for prescribed locations and Iíd recommend upgrading for them. If you really want to go high-tech speak with the electrician about adding arc-fault interrupters on certain circuits. They can tell the difference between the arc a light switch makes when it switched on from arc of a sparking wire or connection and open the circuit. Newer houses have then on all bedroom circuits.
What can go wrong with the wiring in your house can go wrong in a house of any age-- even new. Things like a wiring cable getting damaged by a mis-driven nail or screw by someone mounting something to a wall or ceiling after the house is complete. A rodent-- mice and squirrels-- getting into an attic, crawl space, wall or basement and dining upon the wireís insulation that can shock the critter and start a fire. That happens from time to time. A loose connection from a sloppily installed switch, plug, light, fan or any other device attached to the wiring system that can heat up because itís loose, creating resistance to current flow. Outlets that get worn out due to numerous repeated usages-- such as the upper outlet of a duplex wall outlet in a carpeted hallway or room where the vacuum cleaner gets plugged into time and time again and the outlet becomes loose-- again, causing resistance.
Unless wiring gets physically damaged or overloaded it just doesnít wear out because itís old. Insulation can get brittle over time but even if itís brittle it will be fine if left undisturbed. Itís the points of connection where you can have trouble but if something is installed and connected properly there should be no problem. Pre-1940 wiring is often insufficient for todayís loads. We who have lived in older homes know that using the coffee maker and toaster at same time will send us to the basement to replace a blown fuse. To avoid that some folks will replace a blown fuse with one of higher amperage-- too high for that particular circuit and thatís how fires get started.
There is some merit to the notion that after a period of unknown or unspecified length even breakers can become unreliable due to age. They are mechanical devices that are designed to open a circuit in response to heat-- too much current draw on the device will heat it up to a point at which a bi-metal device trips and opens the circuit. Some have been known not to do that. Certain brands of circuit breakers have a better reputation than others. Electricians know.
I went into a 25 year old house that had two electrical panel boxes. The room I was standing in was lighted by overhead lights. I switched one box off and the lights stayed on. I switched the OTHER box off and the lights still stayed on. Obviously there was a failure the likes of which would only show up should the current draw to the box exceed the boxís capacity and the main breaker would not switch open. The person determining that would be the fire investigator. That happened at a famous boatyard fire locally years ago. The next time I went back to that house there were two brand new panels of a more reliable brand (Square D).
If there are any ďsleeping dogsĒ in this electrical system Iíd start looking at the breakers. It might be prudent to call a licensed electrician to go over the box and render an opinion. Itís not very expensive to replace breakers one by one. The cost of replacing the whole distribution panel the size of yours and not increasing the service size-- because you donít need to-- is in the $1000 to $1400. range. But call in the electrician to take a closer look.