These cables do get confused quite often because a lot of the time in the electrical field installers, contractors and electricians simply ask for a “10 2 cable”. That’s not very precise because as someone who’s been in the industry for quite some time I could name about 5 cables that have two 10 AWG electrical wires in them.
Simply put, Romex® is an indoor cable and UFB is an underground cable. There is also a cable built to fit in between those to as an outdoor cable which is Metal Clad or MC cable. These are the most typical types of electrical cables used in the residential and commercial industries. They commonly come on 250 foot spools or 1000 foot spools.
The 10 AWG conductors in both cables are a solid strand of copper for the least amount of flexibility possible. The reason installers want a stiff cable is mainly for snaking it through conduit and walls of residential homes. Trying to snake a flexible cable through conduit would be very difficult as it would get bunched up and prove to be very ineffective.
Romex® is manufactured by twisting the conductors very slightly throughout the cable in order to make it round overall. UFB cable has added protection with a tougher jacket and each conductor is wrapped individually in a flat form. The result is somewhat of a rectangular look that makes it easy to lay in the ground once a small trench is created.
Another similarity of the two cables is that they both have THHN wires as the inner conductors along with an additional bare copper ground wire. That doesn’t mean they can last in the same environments because of the differences in the outer jacket. The tough outer jacket is more expensive to manufacture and therefore drives the cost up on UFB cables with the additional characteristic of being used directly underground.
If it seems like you need something different after reading this article you should speak to your supplier of electrical wire for more help. They are trained heavily on the different approvals of each type of insulation and where they’re allowed to be used according to the NEC code. In the end passing inspection shouldn’t be a problem because if the inspector lets you know something is wrong then it’s obviously been a problem in the past. Make sure you listen to them and comply with everything they tell you or more problems will arise in the future.
WesBell Electronics is a wire and cable distributor that stocks Romex® and all types of hook up wire. Romex® 10 2 wire is a common item that we have in our inventory in 2 or 3 conductor with an additional ground wire included.