Home fix: DIY electrical repairs are not a good idea

Q. I was changing the light switch in my bedroom to a dimmer switch and got quite a shock. I had turned off all the power to the bedroom and I even checked the outlets to make sure the power was off. When I removed the switch and touched one of the wires I received a shock. How is that possible when the power is turned off?

A. I strongly discourage any do-it-yourself electrical repairs, because the outcome can be fatal. One small mistake and you could be electrocuted and/or cause a fire.

If you must do electrical repairs, make sure all the circuits are off at the main breaker or at the fuse disconnect. Once the work is completed, have the repairs inspected by a municipal inspector or a licensed electrician before restoring the power.

Here’s a simple explanation of what may have happened.

The lighting circuits and bedroom outlets in the room where you were working are probably all on one circuit. A modern home uses Romex wiring where the black (positive) wire is used to feed power to the light or outlet and the white wire is used as the neutral. If you have an older home, you will find that the wiring is not color-coded and you would need the assistance of an electrician to make proper and safe connections.

If, at some point in the home, the feeder wire and neutral wire are reversed at a switch or outlet connection, the current can feed back to the neutral side of the electric panel to the wire you are touching. This is because all the neutral wires are connected to the same neutral buss bar inside the panel and they can become energized if there is a reversed polarity problem anywhere in the house.

Reversed polarity is quite dangerous and needs to be corrected. At switches and outlets, the neutral wire is connected to the silver screw and the feeder wire connects to the brass-colored screw. Modern outlets will even be marked for the white-wire connection. The green screw is for the bare or green grounding wire in the cable.

You can check outlets for reversed polarity by purchasing a plug-in polarity/grounding outlet tester. A simple tester retails for less than $12 and is available at home and hardware stores. If all the outlets check out as being wired correctly, then hire an electrician to inspect the wiring connections at the light fixtures and lighting switches where the black wire, not the white wire, is supposed to be switched.

Q. What is Romex wire? The person who inspected the house I’m selling will not return my calls to explain where the wires are located and why they have to be protected.

A. A professional home inspector cannot release information to you, to the selling agents or to anyone without the permission of the person who hired him.

The ethics code for the American Society of Home Inspectors (ASHI) states: “Inspectors shall not disclose inspection results or client information without client approval. Inspectors, at their discretion, may disclose observed immediate safety hazards to occupants exposed to such hazards, when feasible.”

This may be one reason your phone calls have not been returned. However, common courtesy would require the inspector to make some contact just to let you know why he cannot reveal information. If the wiring is dangerous, the inspector has an obligation to inform you.

Romex wire is a brand name commonly referred to in the trade as “nonmetallic sheathed cable,” typically found in residential construction. Romex consists of three separate wires all protected by an outer layer of insulating materials. Of these three inner wires, two are also insulated and one is an uninsulated or bare copper wire.

I understand that when the insulated Romex wire is installed in a location easily accessible by humans, it should be protected against accidental impact or contact. If the outer layer of insulation is accidentally damaged and one of the two insulated wires also is damaged, you would be exposed to a possible electrical shock.

I often see Romex wiring in good condition but exposed under kitchen sinks for a garbage disposal, or the wiring is exposed from the service box to an electric water heater.

In either instance, the Romex wire’s outer protective insulation could be damaged by accidental impact, which could expose the 120-volt wires to human contact. Such contact can cause a serious shock or even death, making the wiring’s protection extremely important.

Q. We purchased a home last spring, having moved to the Midwest. Last month while window cleaning I noticed that the windows would not crank open. When I looked closer on the outside, it looks like the bottom of the window frame is bowed where it rests on the bricks. Can you give me some idea of what’s happening and what I can do to fix this?

A. There are two types of windows with cranks. One is an awning and the other is a casement style. If the home is less than 50 years old, you probably have casement windows that can get stuck due to wood shrinkage.

When the home was first built, the wood walls and floor systems contained small amounts of moisture trapped in the cells of the wood. Over time, as moisture levels dropped, the wood cells would move closer together and the wood would begin to shrink. Before the exterior brick was installed, the casement windows were attached on the exterior to the wall’s studs. As the wood shrinks, it pulls the window’s sill down and against the bricks, which do not shrink. This causes the windowsill to bow or curve and when you try to open the window it hits the bowed sill and gets stuck. Casement windows on the second floor of a two-story home are more susceptible to this type of damage because there is another eight to 10 feet of wood under the window that can shrink.

The windows are installed from the exterior by nailing the window’s flange to the window opening. I’m not aware of any way to make the repairs from the interior. For metal clad or vinyl windows, I have been told the easiest repair is to remove and then replace the brick sill under the window while others have suggested window replacement. Wood-frame windows can be repaired by removing a small portion of the wood sill to allow the window to open. If the windows have other problems, such as only having single panes of glass, the hardware is damaged or double panes of glass are fogged, then window replacement should be considered.

Ÿ Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home improvement questions at C. Dwight Barnett at d.Barnett@insightbb.com.

Scripps Howard News Service