Thhn and thwn wires both belong to the category of building wires. So what does this letter mean? What is the relationship and difference between these wire models?
Okay, let’s break it down in a detailed way. THHN and THWN cables have its own characteristics that make them better suited for different tasks. Knowing the differences can save you time, money, and avoid a lot of burn down the road. Then let’s unravel this wiring solution together!
Thhn wire: What it means and when to use it
What is THHN Wire?
THHN wire is designed with a polyvinyl chloride (PVC) insulated nylon sheath. The “Thermoplastic High Heat-resistant” part of its name refers to the wire’s ability to withstand high temperatures, making it suitable for use in environments where heat resistance is a critical factor. The “Nylon-coated” component indicates that the wire is coated with a layer of nylon, which provides additional protection and durability.
Where is THHN Wire Mostly Applicable?
Building Wiring Systems: THHN wire is one of the components used in the construction of residential as well as commercial building wiring systems and specifically the conduit type system where the wires are run within a conduit or a raceway.
Appliances and Machine Tools: THHN wires can also be classified among the cable wires which are widely used for their heat resistance and oil repellent reputation in appliances and machine tools wiring arrangements where heat and such oils and chemicals are present.
Dry Environments: The thickest insulating sheath encasing the THHN wire makes it appropriate for dry environments only. Even though it is rated suitable for wet conditions, its rating goes down to a lowly emphasizing 75 °C (167 °F), which temperature is hardly bearable when moisture is constant.
Conduit Applications: THHN wire is often also used in applications where metallic or plastic nylon pipes enclose the wires and wire conduits are in place.
Thwn wire :What it means and when to use it
What is THWN Wire?
THWN wire stands for Thermoplastic Heat and Water-resistant Nylon-coated wire. This wire type features thermoplastic insulation and a nylon coating. These materials provide excellent heat resistance and water protection. THWN wire is rated for wet environments and can handle temperatures up to 90 °C.
Where is THHN Wire Mostly Applicable?
Outdoor Installations: THWN wire is perfect for outdoor wiring projects. The water-resistant feature ensures safety and reliability.
Wet or Damp Environments: THWN wire is specifically designed for use in wet or damp environments, such as basements, crawl spaces, and outdoor applications where wires may be exposed to moisture.
Underground Conduits: Use THWN wire in underground conduits where moisture is a concern.
Industrial Settings: Industrial environments often require wires that can handle heat and moisture. THWN wire meets these demands effectively.
Thhn vs Thwn:What is the difference?
- Temperature Rating
THHN wires are rated at 90 degrees Celsius when used in dry environments. However, the temperature rating is reduced to 75 degrees Celsius in case of wet environmental conditions.
THWN wire remains the same rating of 90 °C in dry and wet conditions. This uniformity makes THWN wire more diverse
- Water Resistance
THWN wires have a higher water resistance capability.The “W” in THWN indicates that it is suitable for wet environments.THHN wire lacks this special waterproof capability.
In a humid environment, the performance of THHN may not be as stable as that of THWN.Now, many THHN wires have dual ratings and can be used in wet locations.However, THWN wires are still an excellent choice for humid environments.
- Construction and Materials
Both wires have burr polythene coating and nylon material. It is these materials that provide resistance to becoming brittle and also enable flexibility. The main difference is in the waterproof character of THWN wire. This improves THWN wire performance in harsh conditions. THWN wire comes with a copper and aluminum conductor core. While copper wire has better electrical performance, aluminum wire is cheaper.
- Usage Differences
Indoor applications: THHN wire is meant quite well for regions with low moisture as dry locations; this wire in particular has a high heat-resistant nature which is very helpful in indoor wiring activities. That is why THHN is a very popular selection among electric engineers for residential and commercial usages.
Outdoor and Wet Environments: THWN wire is good under outdoor and wet environments. It is impervious to water – thus safety and reliability in wet environments are assured, thus THWN wires are the best in underground conduit and outdoor usage.
- Thhn vs thwn price
A THHN wire is generally less expensive costing between 0.10 – 0.50$ a foot on average. For instance, 1/0 thhn wire will set you back $0.2 per inch.
The cost of THWN wire increases as it is designed to be used in extreme weather conditions as it is, in greater cost components like $0.25 per foot.
We are aware that you are interested in learning more about different kinds of cables as well, for example, XHHW-type cables or thwn-2 meaning and we have provided an exhaustive comparison table for you to refer to:
| Feature |
Full Form |
Insulation |
Jacket | Temperature Rating Dry | Temperature Rating Wet | Voltage Rating | Applications | Advantages |
| THHN | Thermoplastic High Heat-Resistant Nylon-coated | Thermoplastic | Nylon | 90°C | 75°C | 600V | Conduits, machine tool wiring, appliances | High heat resistance, flexible, cost-effective |
| THWN | Thermoplastic Heat and Water-Resistant Nylon-coated | Thermoplastic | Nylon | 75°C | 75°C | 600V | Conduits, machine tool wiring, wet or dry locations | Moisture resistance, versatile |
| XHHW | Cross-Linked Polyethylene High Heat-Resistant Water-Resistant | Cross-Linked Polyethylene | Bare or
Nylon |
90°C | 75°C | 600V | Direct burial, raceways, wet or dry locations | High heat and moisture resistance, excellent insulation properties |
| XHHW-2 | Cross-Linked Polyethylene High Heat-Resistant Water-Resistant Type 2 | Cross-Linked Polyethylene | Bare or
Nylon |
90°C | 90°C | 600V | Direct burial, raceways, wet locations,conduits under 600V | Superior heat and moisture resistance, UV resistance for outdoor use |
Which One Should You Use?
Dually, it is safe to handle both THWN and THHN wire in an industrial setting even though both have their limitations. These factors determine the choice; THWN wire works better in high humidity conditions; on the other hand, THHN wire works better in dry high temperature a lot of the times tropical climates.
If you are working on a project and require a specific product (such as thhn/thwn-2, automotive wire types or solar cables), we can support you. Whether it’s a simple question or you need some guidance, please feel free to contact one of our ZW representatives by e-mail.
