Dear Mr. Electrician: I recently purchased my first home and noticed that there are some repairs that need to be done. How well do you think a person such as myself could perform minor electrical repairs and perhaps install some new wiring?
Answer: Experience is very important when doing repair work around the house or new installations. Each trade has different challenges and levels of mechanical aptitude to be successful. The electrical trade learning curve is very great with a combination of classroom training and several years of working under experienced people. In addition an investment in specialty tools is required.
I have made many repairs to DIY wiring and have observed many code violations and poor installation methods. Below is a partial list of common electrical wiring mistakes I have encountered.
Not reading or consulting the newest edition of the “National Electrical Code” (NFPA 70). It is imperative that electrical wiring be installed in a safe manner. The NEC is published and updated every three years to stay on top of the ever changing needs of the consumer and industry while providing the latest rules and guidelines for safe electrical installations.
Please be advised that in addition to the “National Electrical Code” some towns, cities and states have their own electrical codes that must be followed. It is a good idea to contact your local building department to see what codes are in effect. In many cases other codes may be applicable to electrical installations such as a fire code, energy code, sound code, building code etc.
Not considering the safety of your actions. Working with electricity and wiring can be hazardous to your health. At the very least goggles, gloves, and a disposable dust mask should be part of your tool box. Good high back work shoes with steel toes are what many construction workers wear on their feet for comfort and protection. You should consider the same. Consult OSHA Publication #1926 for the guidelines for safety in the construction industry.
In addition it is most likely that the wiring that you install will be used by others. It is important to ensure their safety with a minimal of risk by following the building codes.
Not getting an electrical permit or having your electrical installation inspected. There are a few arguments for NOT getting a permit or having an inspection performed such as government infringing on the rights of individuals or refusing to pay the cost of the permit and inspection. SAFETY is paramount and quashes all arguments against permits. If you are a non-professional doing an electrical installation in your home, you need confirmation that the work is done in a safe and workmanlike manner. The safety and well being of you, your family, and your home are at stake. Doing the job right includes a permit and inspection by your local building department or whatever authority has jurisdiction on home improvement in your community. Sometimes owners in a community have an additional authority such as a homeowners association or management company that must be consulted before any work is performed.
Using undersized electrical switch and outlet boxes to accommodate an abundance of wires. As described in the NEC, a certain volume of space is required in electrical boxes for each electrical conductor. The required amount varies according to the size wire being used and if any wiring devices such as switches and outlets are installed in the box as well. Consult article 314 and table 314.16(A) and table 314.16(B) in the “National Electrical Code” (NFPA 70) for more information.
Calling an electrician to install wiring AFTER you have painted and decorated. Wiring needs to be installed inside of the walls and ceilings. Sometimes holes need to be made in the walls and ceiling to install wiring for receptacles, switches and light fixtures. Call an electrician BEFORE you do any painting and decorating if you plan to have lighting, outlets and switches installed. Form follows function.
Cutting the wires in outlet, switch and junction boxes too short. Conductors should be long enough to extend past the outside edge of the box at least three inches. Read article 300.14. Longer conductors make it easier to work on them. If there is not enough room to push the wires into the box comfortably then you may need a bigger box.
Not grounding metal boxes properly. Anything metal that carries electrical conductors or contains wiring devices must be grounded. If you are using type NM-B cable it contains a separate bare copper grounding conductor. This must be secured to a metal box using a separate machine screw. A cover screw or a screw that secures the box to a wall or ceiling cannot be used to attach the grounding conductor. All metal boxes have a tapped hole for a 10/32 screw (#10 machine screw with 32 threads per inch). Use that hole and a 10/32 green grounding screw to ground the box. Read section VI in Article 250.
Not locating underground utilities before you dig. Call 811 to arrange to have a mark down of all of your underground utilities for FREE before you dig anywhere on your property. 811 is a national hot line that will contact all of your local utility companies and arrange for them to come out and locate and mark where your water, gas, electric, telephone and cable TV services are located.
Using an extension cord for permanent wiring. Different types of wires and cables are approved for various purposes. Cords that are approved for portable and temporary use are not to be used as permanently installed wiring. The insulation has different properties and characteristics that make it unsuitable for long term installed use. In some instances the insulation will eventually dry out and break off exposing the bare copper conductors. Read articles 310, 400.7 and 400.8 in the “National Electrical Code” (NFPA 70).
Using NM-B cable underground. You must use cable and wire rated and labeled for underground use even if it is in conduit. Moisture still condenses inside of an underground conduit and can cause problems leading to failure of the cable. Do not use NM-B in the ground directly or in a conduit buried in the ground. Use type UF cable for direct burial underground wiring or THWN conductors inside of a conduit that is buried underground. Article 334 covers NM-B cable and UF cable is under Article 340.
Wiring under-cabinet lights wrong. A common type of under-cabinet light that is sold in retail stores has a plug and lamp cord already attached to the fixture. It is only safe to use that light by plugging it into an electrical wall receptacle. It is not safe to cut the plug off and install the lamp cord into the wall and control the under-cabinet light using a wall switch. The proper method is to have an electrical receptacle controlled by a wall switch or use under-cabinet light fixtures that are approved to be hard wired directly. These can be purchased at a lighting store or an electrical supply company. There are also low voltage options for under-cabinet lighting which has looser code requirements for wiring.
Splicing wires together without a junction box. I see this a lot. Two or more cables are spliced together using wirenuts, usually, but there is no junction box. The wires are just hanging out, sometimes in an attic, other times in the basement. Wires must be spliced inside of a junction box. See article 314 in the “National Electrical Code” (NFPA 70) to determine the correct size junction box based on the number and size of conductors that you plan on splicing.
Read some of my safety tips here.