4 differences between UF and Romex Cable

If you are looking for shielded cable options for your electrical wiring, have a choice between NM cable and UF cable for your project. 

Although there are some similarities in the two types of electrical wiring, there are also some specific differences. 

So this article describes some of those differences and why you should know about them.

NM or NM-B cables are “non metallic”, which helps flexibility. The “B” denotes a heat rating of 194 degrees Fahrenheit. UF cables stand for “underground feeder” and can look like NM cables.

1. Coating protection

The most significant difference between NM cable and UF electrical cable is the type of sheathing that is used. 

Although NM cable is covered with a flexible thermoplastic jacket on the outside of the cabling, they protect the cable strands with little more than paper wrap. 

UF cable uses a solid thermoplastic outer jacket, and someone also encased each individual cable in a protective sheath. 

This is a specification to regular insulation that is installed in thin gauge electrical wire, therefore UF electrical wiring offers much better sheath protection than NM type and is rated for outdoor, ground and in humid areas.

2. Indoor and outdoor use

Almost all municipalities and local building inspectors restrict the use of NM cable for interior projects. 

That means it cannot use NM cable for cable outlets, fixtures, or other exterior items that are used outside of the house. 

I approve UF power cord for most areas as outdoor accessories and power cord.

UF cable can include being buried underground with no electrical conduit or any other type of protective covering. 

This is because of the thick rubber coating used, as well as the individual coating for each electrical cable. 

Of course, it can also use the UF cable inside the house. With that in mind, if you have a simple DIY project inside the house, NM cable is fine. 

If you need to wire something outside your home, choose UF wire.

3. Need for conduit

As mentioned above, UF electrical cable does not require the use of conductors or any other type of protective covering. 

In most cases, this also applies to indoor wiring projects, except where they are subject to physical damage, such as where the wire exits the ground. 

Then a conduit is required, usually electrical PVC.

While we can use NM wiring without conduit in many areas, there are some parts of the country where the local building inspector may request that you run NM wiring inside a piece of conduit. 

So, if you want to avoid conduit altogether, choose UF power cord.

 In fact, if you consider the cost of NM cable and conduit, buying UF cable is a better option when trying to save some money.

4. Cost difference

Generally , there is a 15-20 percent price difference between the cost of NM cable and the more expensive UF power cable. 

However, if you consider UF cable has better shielding, does not require conduit, and is much more accepted by local building inspectors, the slight price difference could be negligible.


Leave a Comment