Home Wiring | House Rewire

Upgrading your electrical wiring is a big job because the wires are located inside of walls, where they are difficult to get at without opening up walls. The price for a whole-house rewiring job—including opening up walls, running new wires, connecting switches, outlets and fixtures, and then repairing the mess—is $3,500 to $8,000 for an average-sized home.

The best time to rewire is during a remodeling project, such as renovating your kitchen or adding a family room, when subcontractors are opening up your walls anyway. That way, your electrician has easy access to the walls, and refinishing walls will be part of the larger remodeling project—not just the rewiring.

Structured wiring is a smart investment and may be a marketing advantage if you should decide to sell your home. Structured wiring is a generic term for any heavy-duty electrical and data cables designed to handle the latest entertainment and communication devices—and those yet to be invented—including phones, Internet, and household heating and lighting systems.

While a standard electrical upgrade essentially maintains the value of your home, adding structured wiring can increase it. According to a study by the Consumer Electronics Association and the National Association of Home Builders Research Center, almost 50% of homes built in 2008 included structured wiring, a sure sign of its growing value to home owners.

Electrical wiring

Building wiring is the electrical wiring and associated devices such as switches, meters and light fittings used in buildings or other structures. Electrical wiring uses insulated conductors. Wiring safety codes vary by country, and the International Electro technical Commission (IEC) is attempting to standardize wiring amongst member countries. Wires and cables are rated by the circuit voltage, temperature and environmental conditions (moisture, sunlight, oil, chemicals) in which they can be used. Color codes are used to distinguish line, neutral and ground (earth) wires.

Wiring methods

Materials for wiring interior electrical systems in buildings vary depending on:

Intended use and amount of power demand on the circuit

Type of occupancy and size of the building

National and local regulations

Environment in which the wiring must operate.

Wiring systems in a single family home or duplex, for example, are simple, with relatively low power requirements, infrequent changes to the building structure and layout, usually with dry, moderate temperature and non-corrosive environmental conditions. In a light commercial environment, more frequent wiring changes can be expected, large apparatus may be installed and special conditions of heat or moisture may apply. Heavy industries have more demanding wiring requirements, such as very large currents and higher voltages, frequent changes of equipment layout, corrosive, or wet or explosive atmospheres. In facilities that handle flammable gases or liquids, special rules may govern the installation and wiring of electrical equipment in hazardous areas. Wires and cables are rated by the circuit voltage, temperature rating and environmental conditions (moisture, sunlight, oil, chemicals) in which they can be used. A wire or cable has a voltage (to neutral) rating and a maximum conductor surface temperature rating. The amount of current a cable or wire can safely carry depends on the installation conditions.

Modern wiring materials

Modern non-metallic sheathed cables, such as (US and Canadian) Types NMB and NMC, consist of two to four wires covered with thermoplastic insulation, plus a bare wire for grounding (bonding), surrounded by a flexible plastic jacket. Some versions wrap the individual conductors in paper before the plastic jacket is applied. Special versions of non-metallic sheathed cables, such as US Type UF, are designed for direct underground burial (often with separate mechanical protection) or exterior use where exposure to ultraviolet radiation(UV) is a possibility. These cables differ in having a moisture-resistant construction, lacking paper or other absorbent fillers, and being formulated for UV resistance. Rubber-like synthetic polymer insulation is used in industrial cables and power cables installed underground because of its superior moisture resistance. Insulated cables are rated by their allowable operating voltage and their maximum operating temperature at the conductor surface. A cable may carry multiple usage ratings for applications, for example, one rating for dry installations and another when exposed to moisture or oil. Generally, single conductor building wire in small sizes is solid wire, since the wiring is not required to be very flexible. Building wire conductors larger than 10 AWG (or about 6 mm²) are stranded for flexibility during installation, but are not sufficiently pliable to use as appliance cord. Cables for industrial, commercial and apartment buildings may contain many insulated conductors in an overall jacket, with helical tape steel or aluminum armor, or steel wire armor, and perhaps as well an overall PVC or lead jacket for protection from moisture and physical damage. Cables intended for very flexible service or in marine applications may be protected by woven bronze wires. Power or communications cables (e.g., computer networking) that are routed in or through air-handling spaces (plenums) of office buildings are required under the model building code to be either encased in metal conduit, or rated for low flame and smoke production.

Older homes present a number of risks not present in more modern buildings. One of these risks is faulty electric wiring, which combined with lighting equipment failures was responsible for an average of 22,410 fires per year between 2007 and 2011 according to The National Fire Protection Association. Homes built in the early 20th century may contain "knob and tube" style wiring, while those built in the 1960s and 1970s may contain aluminum wiring instead of copper. Both are safe when in good condition, but present an added risk of electrical fire as they degrade over time.

If you are moving into or own an older home, it is important to understand your risk of electrical fire and possibly take steps to update your wiring. 

What to look for
There are a number of warning signs to look for when considering the possibility of faulty wiring, according to HouseLogic.

• Constantly tripped breakers or fuses can mean that your wiring is degrading. It could also just mean that part of your house is drawing an inordinate amount of energy. If a fuse for one specific part of your house is constantly tripping and there are a number of energy drawing appliances getting used simultaneously, this may be the problem.
• A tingling feeling when you touch a switch or appliance may mean that your wiring is being grounded by the object you are touching. This should not be happening, as it means a current is flowing through you every time you touch the object.
• Flickering lights can also be a sign of faulty wiring, or it may be that the light bulb you have installed is simply nearing the end of its life. Carefully replace the light bulb, preferably with a new CFL bulb that is correctly rated for the appliance. If the flickering continues, the wiring is likely to blame.
• A burning smell is never a good sign in any part of your home. If you smell burning every time you use an appliance, your wiring may be to blame.
• Browning outlets can also mean that there is a problem with your wiring, particularly if they are warm to the touch. The more significant the browning, the faster you should act, as this presents a real risk of electrical fire.

Other signs of dated wiring are standard outlets in your bathroom – which were replaced by ground fault circuit interrupters for potentially damp environments in modern homes. In addition, ungrounded – or two pronged – outlets throughout your house can be a sign of dated wiring. Even if there is nothing wrong with your home, if you have only ungrounded outlets you should get them updated. Chances are you are using an adaptor for your appliances that require all three prongs, which is not a safe practice.