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What’s The Difference Between Romex And THHN Wire? (Explored)

What’s The Difference Between Romex And THHN Wire? (Explored)

Electrical wiring is one of the critical components of a building. It helps connect different parts of a structure and transmits electrical current.

Wiring can be made from various materials, including metal cables, plastic conduits, or run-through wood. Different types of electrical wires are used in other applications.

Primary cables are used to carry electrical current from one point to another. They have a thicker coating that helps protect them from corrosion. Secondary wires are smaller and are used to distribute the power from a primary wire. Their thinner coats allow them to travel long distances without damage.

Regarding wiring, Romex and THHN wire are two of the most common options. Romex is more popular because it’s easier to work with, but THHN wire has benefits.

The main difference between Romex and THHN wire is that Romex is heavier duty. It can handle higher temperatures and pressures than THHN, which makes it a better choice for electrical insulation. Additionally, Romex has a rougher surface that helps it resist corrosion.

Let’s indulge in the details of these two types of wires.

What Is Romex?

Romex is a type of wire rope made of high-quality steel used in construction and industrial applications. It can be found in various colors and has a tight diameter to resist kinking.

Fencing made of Romex wire.
Romex is a thick wire that can withstand a tremendous amount of weight.

It’s a type of cable used to protect telephone and electrical wiring. It’s made of plastic and metal strands that are tightly woven together. Romex is usually color-coded to make it easier to identify. Romex is heat-resistant, waterproof, and stable in high winds.

Most commonly used in home theater and entertainment setups, Romex cables are usually heavier than other cable types, making them perfect for installations where longevity is key. They’re also less prone to interference and breakup than different types of wiring, so you can be sure your gear will still work when upgrading.

This versatile cable is perfect for an attractive, high-quality solution without breaking the bank. 

What Is THHN?

THHN wire is made of a tin-lead-antimony-nickel (THHN) alloy. It’s a special kind of wire used in audio and telecommunications applications.

These metal wires have several important qualities:

  • THHN cables are solid and can withstand a lot of punishment. They’re also very flexible, making them ideal for applications where bending or twisting is required, such as a speaker or phone cables.
  • THHN wires are corrosion-resistant, which can hold up to the elements pretty well.
  • In terms of compatibility with other electronic equipment, THHN wire is perfect because it’s low susceptibility to interference and doesn’t generate heat when transmitting signals. This makes THHN wire an ideal choice for high-performance audio and telecommunications applications.

Know The Difference

Romex and THHN wire are two of the most common types of wiring, and each has unique characteristics that should be considered when choosing which type to use.

Here are some key differences between these two wires:

  • Romex is considered a heavier wire than THHN, which makes it more sturdy and resistant to damage.
  • Romex is less flexible than THHN, so it may not be as ideal for installations that need to be moved or reconfigured frequently.
  • THHN is lighter than Romex and has a higher resistance to electricity loss. This makes THHN a better choice for sensitive applications like medical equipment or motors.
  • THHN is more flexible than Romex, so it’s easier to bend without breaking.
  • However, like Romex, THHN isn’t as heat-resistant as some other wires and may spark if disturbed during an installation.

Romex vs. THHN

Romex WireTHHN Wire
Heavier wireLight wire
Less flexibleFlexible
Heat resistantIt cannot withstand high temperatures.
It is used to lift heavy loads.They are used in electrical appliances.
Here is the table of differences between both wires.

Here is a video clip about different types of wire insulations.

Different types of wire insulations

Why Is It Called Romex Wire?

Romex wire is an electrical wire used to construct and maintain electric wiring. The name “Romex” comes from the trade name for a particular brand of insulation made from this wire.

Romex wire is made of several strands of copper wire twisted together. The cables are thick enough to support weight and are covered in a plastic sheath.

Romex is popular because it has a high strand count (meaning there are a lot of wires), it’s easy to work with, and it’s a standard size.

What Is Romex Used For?

Romex is a type of wire netting commonly used in security installations, including fences, gateways, and plant enclosures. Romex is versatile and has many uses, including as a component in security fencing systems, an exterior surface layer for buildings, and a support structure for greenhouses.

An image of fence made of Romex wire.
You can use Romex wire for thick fencing.

Romex is also popular in aerial photography applications because it can handle high winds without suffering structural damage, making it ideal for capturing photos from high altitudes.

Why Is Romex Not Allowed In Conduit?

Romex wiring is not allowed in conduit because it can cause overheating and an electrical fire. The extra thickness and rigidity of Romex wire can also add difficulty in removing it, should a problem occur.

Furthermore, Romex wiring is incompatible with grounding systems, so if there is an issue, it can result in severe electrical shock.

Where Is THHN Used?

THHN wire can be used in electrical applications in a few different ways.

THHN is commonly used as a conductor for audio and video signals, but it’s also being researched as a possible replacement for copper wires in electrical infrastructure. THHN has a low resistance, making it an ideal choice for high-frequency applications.

Image of different colored wires.
You can use THHN wire in different electrical appliances.

Additionally, THHN is not subject to corrosion or degradation by environmental factors like rain or sunlight, which makes it a preferable option for longer-term usage. THHN has numerous advantages over other types of wiring, making it an attractive choice for various electrical applications.

Which Is Better, THHN Or THWN?

THHN and THWN have their benefits and drawbacks, so deciding which is best for your needs is essential.

THHN wire is thinner than THWN wire, making it more suited for smaller wires. This means that THHN wire can be used in places where THWN wire can’t, like between electrical boxes and walls.

Additionally, THHN wire doesn’t create as much heat as THWN wire does, which can be helpful in areas with cold winters or hot summers.

On the other hand, THWN wire is thicker than THHN wire and is better for larger wires. This makes it a better choice for areas with a lot of potential heat exposure, like near fireplaces or high-voltage lines.

Additionally, because THWN wire is thicker, it creates more heat than THHN wire does, which can be helpful in areas with colder winters or hotter summers.

Bottom Line

  • THHN and Romex are types of cables, but there’re some critical differences between them.
  • Romex is much heavier than THHN.
  • Romex is typically used in applications requiring a more robust electrical resistance, such as motors and heavy equipment.
  • THHN, on the other hand, has lower electrical resistance, making it better suited for applications like lighting and electronics.
  • The strands in a Romex cable are tightly twisted together to create a solid line.
  •  In contrast, THHN cables have thinner strands that are not as tightly twisted together.
  • THHN is lighter than Romex and has a higher resistance to electricity loss.

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