What to Know About RHW Cable

Choosing the right cable is important in many construction and industrial projects. This article will focus on RHW cable to help you understand what it is, what environments and projects it can be used in, and how to choose it. By reading this article, you will be able to quickly determine which RHW cable meets your work needs, helping you to minimize selection errors.

What Is RHW Cable?

The name RHW cable can be taken apart and understood: R for rubber insulation, H for heat-resistant, and W for water-resistant. It is a single-core construction cable designed for use in hot and humid environments. With these letters, you can know their basic use and performance.

RHW is a type of building wire that is usually used for laying through conduit. It is not a multi-core cable or a tray cable, but a power cord with a single conductor. It is usually used for wiring from the distribution box to the loads and meets the power distribution needs of residential, commercial, or industrial buildings.

RHW Cable Construction and Wire Options

Bare vs Tinned Copper Conductors

The conductors of RHW cables are commonly made of bare copper or tinned copper. Bare copper has good conductivity, is low-cost, and is widely used in dry environments. Tinned copper has a layer of tin added to the surface of the copper, which prevents oxidation and corrosion, is more resistant to hot and humid environments, and also extends the service life. The type of conductor you choose depends on the environmental conditions and requirements of your project.

Solid vs Stranded RHW Wire

RHW can be made into solid or stranded wire. Solid wire is simple, inexpensive, and good for laying in straight lines over short distances. Stranded wire is softer, easier to bend and thread, and more efficient to construct. The stranded RHW cable is usually chosen where the wiring path is complex or requires more bending.

Insulation Materials Used in RHW Cable

The insulation of RHW cables is usually made of XLPE or EPR. These materials are resistant to both heat and humidity and do not age easily, protecting the current and keeping the cable stable over time. These insulations are more robust at high temperatures and in humid environments than ordinary PVC or nylon jackets.

Available Sizes and Configurations

RHW cables are available in a variety of gauges, commonly 14 AWG, 12 AWG, 10 AWG, 8 AWG, 6 AWG, 4 AWG, 2 AWG, and 1/0 AWG. The different gauges correspond to different current-carrying capacities and construction requirements, for example:

• 14 AWG, 12 AWG: Low-power branch circuit wiring for lighting and small outlet wiring
• 10 AWG, 8 AWG: Medium power branch circuits for small appliances, air conditioners, or distribution branch circuits
• 6 AWG, 4 AWG: High power loads for distribution boxes to major appliances or large air conditioners
• 2 AWG, 1/0 AWG: Trunk power or industrial equipment power lines

RHW Cable Performance Characteristics

Electrical Ratings and Compliance

RHW cable is typically rated at 600V. It meets standards such as UL 44 and NEC, which ensure that the cable meets safety requirements when used in commercial and industrial buildings. Choosing a cable that meets the certifications can help you avoid acceptance issues and also reduce safety risks.

Temperature Resistance and Heat Performance

The standard version of RHW has an operating temperature of 75°C, while the RHW-2 version can reach 90°C for long-term use in dry or humid environments.

Moisture and Wet Location Suitability

The W symbol on RHW cables indicates that they can be used in wet environments and are often used in basements, wet industrial areas, or for outdoor wiring through conduits. RHW can withstand more water vapor or moisture than RHH cables without a W. However, ordinary RHW cables are not intended for direct burial, and if direct burial is required, conduit must be used, or a cable with a direct burial rating must be selected.

Fire and Safety Considerations

RHW cables have basic flame-resistant properties to slow the spread of fire in the event of a building fire. Some versions are also available in low-smoke, low-toxicity materials to reduce harmful emissions in the event of a fire. Regardless of the version, it is important to consider the safety requirements of the entire cabling system when selecting cables.

Applications of RHW Cable

Commercial and Residential Buildings

RHW cable gets extensive use in commercial as well as residential buildings. The cables are mostly employed to move wires between the distribution box and individual loads that include light, outlets, and appliances. The basement, designated equipment area, as well as in-wall conduits, represent some of the usual places where these cables lie within their wiring.

Industrial and Utility Installations

RHW cable is also common in factories or industrial projects. It can be used in control cabinets, electrical rooms, or power lines for large equipment. Because it is heat and moisture-resistant, it can cope with temperature and humidity changes in industrial environments. Selecting RHW can reduce the frequency of wiring failures and maintenance, and keep your equipment running reliably.

Solar and Renewable Energy Systems

RHW-2 cable is also frequently used in solar photovoltaic systems. It connects PV panels, inverters, and distribution boxes and withstands outdoor temperature and humidity changes. While some projects also use USE-2 or PV Wire, RHW-2 provides clearer specification support and facilitates project acceptance.

RHW vs Other Building Wires

RHW vs RHH Cable

RHH cables are very similar to RHW, but RHH does not have the W symbol and is not meant for wet environments. RHH is better for dry environments or indoor pipe laying. If there are wet areas in the project or if there may be moisture in the pipes, RHW should be chosen over RHH.

RHW vs XHHW / XHHW-2

Both XHHW and RHW can be used in high-temperature environments, but XHHW uses a different insulating material with slightly different heat and moisture resistance. XHHW-2 is similar to RHW-2 in that it can be used for long periods of time in humid environments. Your choice can be based on project specifications and wiring paths to determine which cable is more appropriate.

RHW vs USE-2 Cable

USE-2 is a cable that is mainly intended for service entrance or direct burial and is more resistant to the environment and water. RHW is generally intended for conduit distribution inside the structure and cannot be buried directly. The most obvious distinction between the two cables would be their intended usage and environment, and these cables cannot be substituted for each other.

How to Choose the Right RHW Cable

Consider the Installation Environment

Before making the selection, you need to consider the wiring path and the environment. Dry indoor conduits can use standard RHW, while wet environments or conduits where moisture may be present require the selection of RHW cables with W. High-temperature areas or lines near heat sources should consider RHW-2 or a higher temperature-rated model. By judging the environmental conditions, premature cable deterioration or damage can be avoided.

Select the Correct Wire Size

The selection of wire gauge needs to be based on the current rating and length of your line. Use 14 or 12 AWG for low-power branch circuits, 10 or 8 AWG for medium-power branch circuits, and 6 AWG and above for high-power lines. Choosing the right wire gauge ensures stable cable operation and avoids overheating or safety risks.

Meet Local Codes and Project Specs

Selection must be in accordance with the NEC or local electrical codes, as well as project design requirements. Even if cable performance is adequate, it may be rejected at acceptance if it does not meet code. Look for certification marks and voltage and temperature ratings to ensure that the cable meets the project requirements.

FAQ

How Well Does RHW Cable Age With Long-Term Exposure To UV Light?

Although the PVC outer sheath of RHW cables has some UV resistance, it is not specifically designed for long-term direct exposure to sunlight. If it needs to be laid outdoors overhead, long-term UV exposure may lead to aging and cracking of the sheath, which in turn affects its moisture resistance and insulation properties.

Therefore, when using RHW cables outdoors, it is best practice to install them in cable trays, conduits, or ducts to provide shade, or consider selecting models labeled “sunlight resistant” such as RHW-2 or USE-2.

Can RHW Cable Be Used As A Temporary Replacement For THHN Cable in Pipelines?

In terms of electrical performance and safety standards, RHW cables are rated to fully meet and exceed the requirements of THHN and are therefore a viable temporary replacement for use in pipelines.

RHW has better heat and moisture resistance properties. However, it should be noted that RHW cables are typically thicker, stiffer, and more costly, and may be more difficult to construct for routing in conduits.

What Are The Differences Between UL-Certified RHW Cables And CSA-Certified Ones?

Both UL (U.S.) and CSA (Canada) certified RHW cables meet North American safety standards and have similar performance, although differences are in the markets they are intended for and some of the testing requirements.

CSA standards typically require cables to pass tests at much lower temperatures (e.g., -25°C or -35°C) to adapt to the harsher Canadian climate.

Therefore, if your project is in Canada, specify CSA-certified RHW cables to ensure full compliance; in the U.S., UL certification is sufficient.

Final Thought

By selecting compliant RHW cables, your purchasing and construction processes can become more efficient. For reliable and compliant RHW cables, you can trust Honest Cable to provide the best solutions and help you select the necessary cables for your project. Welcome to contact us.