With all of this in mind, and after reviewing sections 334.10(3) and the new language of 334.10(1), it is obvious that nonmetallic-sheathed cable may be laid exposed in one- and two-family houses, connected and detached garages, and storage facilities. This includes any attached or detached accessory structure such as a shed, platform, or balcony.
The only requirement is that each room in the house be able to receive electrical service from a separate meter. If this condition is not met, then the cable cannot be exposed in the house.
One common question is whether there are other requirements for exposed wiring. The short answer is no, but there are some limitations based on what type of wiring is being used. With metallic wiring, the voltage must be reduced to acceptable levels for normal household use when it is inside an enclosed area of a building. This means that if your house was built before 1990, the voltage should not be more than 120 volts. If it is higher, then the cable cannot be exposed.
With nonmetallic wiring, there are no voltage limits so long as the overall load on the system is less than or equal to 50 percent of the maximum capacity of the conductor. This means that if your house was built after 1990, the voltage can be up to 600 volts because electric bills would be high but not dangerous.
Electrical wires in a home or finished garage are shielded from damage by permanent wallcoverings such as drywall, plaster, or even wood, but this is not the case in an unfinished garage. The key to safe, code-compliant exposed wiring is to shield and support the wires using frame members. If there is no framework around which to wrap wire, then it should be covered by at least one layer of tape.
The National Electrical Code requires that all exposed parts of household circuits be enclosed in metal boxes or other enclosures designed for this purpose. The code also requires that all openings in metal enclosures be filled with suitable metal screening to prevent animals and children from accessing live electricity.
If you want to work on your car inside a garage but don't want to risk damaging your wiring, then it's best to either hire a professional garage door installer or do it yourself. Make sure that you hire a reputable company that uses certified electricians and that has good reviews from previous customers.
You should also check with your utility company to see if they provide service in your area. Some companies may not offer service if the distance between their main office and your residence is more than five miles. However, most utilities will extend their reach into people's garages where they can connect up to an electrical meter for service delivery purposes.
Yes. In the attic, NM cable may be exposed. This is quite frequent in modern homes. Armored cable or MC is not required in your situation. Just make sure you install all of the cables properly. The metal shield on both sides of the cable protects against electrical noise and corrosion.
If you're just now learning about wiring in attics, don't worry about it. Most attic spaces are well-insulated and have low humidity levels. This means that oxygen is not as likely to cause damage to wires over time. However, if you do see any signs of aging or damage, have a professional repair person perform some extra insulation, paneling, or framing to protect your wiring.
The best way to avoid having to replace your home's wiring is to take care of any problems immediately. Be sure to check all wiring diagrams before you start any work on your house to ensure that you're not cutting into any circuits. If there are any damaged or frayed wires, have them replaced immediately before another problem occurs. Wires that are too close together will produce the same result - bad electricity - and should be moved away from each other. You could also get some rubber insulated cable tape at any home improvement store and wrap some of these lengths of wire to help separate them out.