Some types of electrical wire include THHN, Romex®, UFB cable and bare copper. Each has a purpose in the electrical field so I will give you some basic information to help you make the right decision when wiring your own home.
THHN wire is the single conductor copper wire with a PVC insulation and a nylon coating. You can notice the glossy feeling of the outside of this type of wire and the bare copper, or brass, color to the inside strands. This type of wire is the foundation, or start, to all of the electrical cables I will discuss with you in this article.
Romex® cable is a cable with more than one THHN wire and a bare copper ground. Romex® was made so that more than one THHN wire can be run from the electrical box to the lighting and appliances in your home. THHN is the wire needed but NMB cables can ease the situation by running more than one wire at a time. The thin PVC jacket, however, can not be used outdoors at all even if it is only 2 or 3 feet.
MC cable is a metal clad electrical cable used indoors more often to replace NMB cable and conduit together. MC cable has an aluminum interlocked armor that acts as its own conduit when used in indoor applications. It can also be installed outdoors and in conduit when needed because it has all four insulated conductors.
UFB cable is an underground cable used directly in the ground without conduit. Sometimes underground electrical wire is used in conduit too, electrical cable gland which can protect the cable for a longer period of time, but it’s definitely not needed. UFB cable has the tough outer jacket to withstand the underground abuse.
You can probably tell by the construction of these electrical cables which one is the cheapest and most expensive but I will tell you anyways. THHN is just one wire so it would be the cheapest and the UFB cable is the most expensive due to the construction and available use outdoors.
Make sure you speak to your wire and cable supplier in order to understand exactly what you’re going to buy. There are so many different types of wire and cable that it’s very difficult to get exactly what you need unless you ask around. There are very slight variances between each wire in order to supply all applications with the correct insulation and voltage requirements.