Since there are so many types of electrical wires in the industry, you’ll need to determine where it will be installed and how much power must be passed through it before purchasing anything. Certain cables are designed for indoor use while others are designed for outdoor use and their cost is directly affected by how much they can handle. More work by engineers and higher manufacturing costs result from outdoor or underground cable.

NMB means non-metallic because there is a “metallic” electrical cable that is used outdoors and in conduit. The non-metallic version is for indoor use only at a much cheaper price. The ground wire does not need to be insulated and the outer jacket does not need much protection. The main reason for the jacket is so that the contractor can run multiple electrical cables at once instead of individually.

UFB means underground feeder because it is used for installations that are buried directly in the ground without conduits. It is a flat cable and the heavy-duty PVC jacket covers each THHN cable individually for added protection. Again, this cable can be buried in the ground without conduit, but it will be much more expensive than NMB cable due to the additional approvals and manufacturing costs.

There is also an electrical wire between these two, in cost and in environmental installation capabilities. MC Cable Holders for Metal Clad which is the “metallic” wire mentioned above. Metal jacket (aluminum interlocking armor) wraps around all THHN conductors, allowing for use outdoors and in conduit applications. Also passes as its own conduit for indoor applications only. Many times, a contractor will first need to run conduit and then install NMB cable inside. However, now they can simply buy MC cable and install it without conduit to save time. MC cable is NOT approved to be buried directly in the ground.

Think about the 3 main electrical installations which are indoors, outdoors and underground.. Additional approvals and requirements are needed for each environmental change. In addition, more engineering and manufacturing costs are needed to make the more difficult cables, such as the UFB underground feeder. The only thing they have in common is the internal conductors of THHN THWN. The change is more in the jacket material than the inner conductor insulation because that’s where most of the protection comes from.

Be sure to talk to your wire and cable provider before making a purchase so you don’t overspend or possibly underestimate the amount of protection you need.