Breaking Down RHW-2, USE-2 and RHH Wires

Kelly Benjamin
August 15, 2017

You’ve probably noticed the codes and abbreviations you see on certain wires and cables. But unless you’re a wire technician or experienced working with cables, it’s likely that you don’t know what those letters and numbers mean. And that’s okay; we’re here to break down what some of those signify and how they can affect your next choice when it comes to buying wires and cables.

All electric wires and cables must be labeled appropriately by following the National Electric Code (NEC) guidelines. This ensures that consumers and users know exactly what type of wire they are using – an important factor to know when it comes to working with electrical systems.

We’ll start with RHW-2 wires.

R: Rubber insulation

This rubber outer layer is very important when it comes to copper cables, especially when those cables are utilized in possible hazardous environments. Performance Wire and Cable’s RHW-2 wires are insulated by cross-linked polyethylene. Even though the “R” stands for rubber, it also incorporates other neoprene insulations that XLPE falls under.

H: Heat resistance of 75 degrees Celsius

Again, cables must be able to withstand the elements. You’ll occasionally see “HH” on some wires, which details the wire’s ability to resist heat up to 90 degrees Celsius. The insulation’s length and width help determine its heat resistance. The thinner the XPLE is, the less resistant it is to heat.

W: Water resistant

Manufactured in USA RHW Cable from Performance Wire and CableDepending on location, this factor could be the most important for your wire. The “W” label even suggests that the cables can be submerged in water if needed. Even if the wire has “R,” which means it is acceptable to use in damp locations, it is wise to keep these wires away from water if the “W” isn’t present. Wires without this “W” label are susceptible to failure and erosion when exposed to water and other liquids.

So, RHW cable is a wire is insulated by rubber or something else (XLPE), can withstand heat up to 75 degrees Celsius, and is water resistant. That’s why RHW cables are regularly found underground in wet locations. However, the NEC lists RHW-2 as having the ability to withstand heats of up to 90 degrees Celsius, a fact that puts our RHW-2 wires ahead of the competitions’ regular RHW wires.


USE wires are pretty simple, according to the NEC.

U: Underground
S: Service
E: Entrance

So, USE cables stand for underground service entrance cables. Again, for cables to be used underground, they must be able withstand pressure and other elements.


RHH Cables

RHH cables are very similar to RHW cables, with two major differences. While only one letter is different in the respective codes, keep in mind what we talked about above. We already covered that the “R” stands for a rubber insulation and the “HH” details the heat resistance.

R: Rubber insulation
HH: Heat resistant up to 90 degrees Celsius

This means that while RHH cables can withstand a higher temperature than RHW cables, they do not possess the water resistance trait that RHW cables boast. This doesn’t mean one cable is better than the other or vice-versa; it simply means that each cable is specifically designed to work in different locations.

RHW-2 wires are suitable for direct burial in both wet or dry locations. Along with RHH cables, they hold a 600 voltage rating. Both cables can be found in general wiring applications, lighting and power systems – depending on the location and surrounding environments.