The usage of THWN wire is primarily motivated by its resistance to water. These cables are used in situations where a conduit is not required; their added flexibility makes them the favored cable among electrical contractors, as both wire kinds are not required to be carried. THWN has become the standard for new construction and major remodels because it is considered more flexible than other types of wiring and can be cut to length as needed. The only drawback to this type of wiring is that it does not provide much protection against oxygen or nitrogen gases either. These cables are most commonly found in home kitchens where they are usually colored white or gray.
Conduit is a term used to describe an enclosure within which one or more conductors are placed. Conduits provide physical support for wires while allowing them to be pulled through without damaging the insulation. They also provide a means of connecting multiple wires together. Without some form of conduit, every time you add a new room you would have to go back and pull another set of wires into place. This is called a "re-wiring" project and can be very expensive if you have no way of avoiding having to replace parts of the house's circuit breaker panel.
The word "conduit" comes from Latin conducere meaning "to lead", and this is exactly what it does: it leads away from the main body of the house and into each room.
It refers to a single conductor with flame-retardant, moisture- and heat-resistant thermoplastic insulation and an extruded nylon or comparable jacket. A THW wire is a single conductor with flame-retardant, moisture- and heat-resistant thermoplastic insulation. The term "twice as hot" refers to the fact that it will withstand twice as much heat as regular wiring.
THWN is an abbreviation for "triple-wrapped nylon", a type of electrical cable used primarily in outdoor lighting systems. It is also known as "weatherproof cable". The word "nylon" by itself is often misunderstood to mean a generic type of cable; however, "nylon" when used in this context means polyamide plastic.
There are three levels of insulation protection defined by Underwriters Laboratories (UL): Type I, Type II, and Type III. All THWN cables are Type II cable. They can be identified by looking at the color code on the exterior of the cable box or conduit. Black or dark blue cables are usually THWN, while red or pink cables are usually RCD. However, there are exceptions to this rule. For example, some yellow police car lights are made from THWN cable because they need to be able to handle high currents without burning up.
The term "guard" means that there is a second insulated conductor within the first one.
Thermoplastic Heat and Water-resistant Nylon-coated (THWN) is an abbreviation for Thermoplastic Heat and Water-resistant Nylon-coated. THHN is an abbreviation for "Thermoplastic High Heat-resistant Nylon-coated." One of the most prevalent single-conductor wires used in the United States is THWN-THHN-2 wire. Conductors in sizes 14, 12, and 10 AWG can be solid or stranded. The two types of strands in each size are red/black and white/blue.
The term "2-wire" refers to a pair of conductors which carry current on opposite sides of a common, insulated barrier. In other words, if you were to cut the conductor in half, it would still carry current. A neutral is also included in most 2-wire systems. This third conductor serves as a return path for current in either direction along both halves of the cable. Neutrals are required by law for all circuits that supply electricity from the public utility company to consumers' houses. Without neutrals, there would be no way to distinguish between incoming and outgoing current since they would be carried on the same conductor.
In many cases, one conductor is designated as hot and the other as cold. This means that these conductors will always carry current in different directions through the cable. It is important to remember not to touch any part of the cable except for the assigned pins when working with electrical wiring. If you do so, you may be causing serious injury due to the high voltage present on most cables.
Conduit is helpful for running wires of a certain gauge or combination for which a ready-made cable is unavailable, difficult to get, or more expensive than the total of its constituent parts plus assembly costs. For example, it's used when you need to run a 14 AWG wire along with a 4 AWG wire into a junction box. Or you can use it to combine several 2-wire outlets onto one 3-wire plug.
You'll need conduit if you are installing electrical wiring in an area that was not planned for it. For example, if you are building a basement apartment and want to put circuit boxes down there, you will need to run some wiring to those boxes. You could run single circuits to each room or unit (which is the normal practice), but that would leave the rooms without electricity if someone was out at night or if there was a power outage. If this happens, you will need to run a separate circuit for each room or unit. The wiring in these separate circuits does not have to be done in parallel; instead, it can be done serially. That is, one wire goes to one light fixture, another wire goes to another light fixture, and so on. This is called a "series circuit" because the wires act as individual circuits even though they are all part of one larger system.