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Can Romex Be Used Outside? (Answered)

Romex is a wire which is made by a company named Southwire Company. It is famous to people for electrical wiring purposes, especially in the United States.

Although Romex is used for indoor wiring, you may ask can it be used outside. Let us help you find the answer you are looking for and discuss some necessary topics about it:

Can Romex be used outside?

Romex cannot be used outside directly. This means that you cannot use Romex outside of your house by directly burying it or by keeping it in an open environment. If you want to use it, you must run it through a metallic or non-metallic conduit in order to provide it with the necessary protection.

Romex cables are popular for indoor use. People use Romex cable inside their residential and commercial buildings for wiring. Romex comes with a light protective outer layer which is just a PVC jacket. This provides it with the basic protection that is required.

But this PVC jacket is not enough for outdoor protection. The PVC jacket protection may get damaged due to the wet or corrosive environment of the outside. Therefore, exposing the inside of Romex to the open-world which may become a life risk. 

So, Romex cannot be used outside.

As you cannot run Romex outdoor, it is obvious to say that you cannot run indoor Romex outdoor. Indoor Romex is designed for indoor use only. It uses the basic protection layer that is required for public safety. 

The manufacturer does not recommend or certify that it can be used for outdoor use.

Due to the thin protective shielding of the indoor Romex, it is not suitable for wet and corrosive outdoor environments. It may not only damage the cable’s protective layer but also can cause serious problems. Thus, you cannot run indoor Romex outdoor.

What kind of Romex is used outdoors?

There are no Romex that can be used outside. Romex is made for indoor use only. Therefore, it is less costly to produce due to requiring the least amount of protective layer. Thus, you cannot use Romex outside.

You need to use it outside even after the warning by the manufacturer, you will require protection for it. So, you will have to use a metallic or non-metallic conduit in order to use it outdoor.

But there are some Romex called outdoor Romex. It is known as UF cable. This can be called be Romex but technically it is not. Therefore, there are no Romex that can be used outdoors.

Why shouldn’t Romex be used outside?

There are multiple reasons why you should not use Romex outside. Here are a few highlighted reasons why we think you should not use Romex outside:

The manufacturer does not certify it for outdoor use:

Every wire or cable that is available in the market goes through a lot of testing by the manufacturer. The reason is to ensure the quality of the product and the safety of the consumer. 

The manufacturer of Romex, Southwire Company, does not certify this for outdoor use.

Thin protective layer:

Romex cables use a thin protective layer. It is known as a PVC jacket. PVC jacket is simply a layer made of polythene. It is delicate and can be torn easily. As the cable uses such protection, it is not suitable for wet and corrosive environments.

Can get damaged easily:

As Romex uses a PVC jacket as outer protection, it can be damaged due to various environmental elements. The PVC jacket can be easily damaged by water, oil, and soil. Therefore, the supply of electricity will hamper and may cause risks.

Can cause life risks if it gets damaged:

If a Romex is used outside and gets damaged by various environmental elements, it can cause various life risks for both humans and animals.

What is the alternative for Romex to run outside?

THHN is the alternative for Romex to run outside. Most THHN are UF-type. This means that they can be used outside as they are known as underground feeder cables. This comes with a better outer protective layer compared with Romex.

All UF-type cables are certified for outdoor use. They can withstand any wet, dry and corrosive environment. They can go through all of these due to their improved protection layer outside the core. So, THHN is the alternative for outdoor use instead of Romex.

Where can Romex wire be used?

Romex wires can be used in most indoor wiring. It is made in such a way that it can do the job by any means necessary if you use it indoors. If you are asking where can you use Romex wires, let us help you understand that by discussing where some famous Romex wires can be used:

14/2 Romex:

This wire has a rated amperage of about 15A. It is commonly used for lighting outlets as it is perfect for this kind of use. It can help provide electricity to LED lamps, light sockets, tube light sets, and many more.

12/2 Romex:

12/2 Romex has a rated amperage of about 20A. It is commonly used in lighting outlets. As it comes with higher amperage, you can use it in outlet circuits and refrigerators as well.

10/2 Romex:

This wire has a higher amperage of about 30A. As it is a heavy-duty wire, it can be used to run appliances that require a higher amperage connection. You can use it to power your electric water heater and baseboard heater. 

These require a lot of amperages to run and 10/2 Romex is perfect for these.

10/3 Romex:

This wire is almost like 10/2 Romex. It is widely used to power electric dryers. As electric dryers require a three-phase electrical wire, the 10/2 Romex is perfect for this kind of operation.

Can Romex be exposed to sunlight?

No, Romex cannot be exposed to sunlight. Romex cables are highly sensitive to sunlight. The UV rays of the sun cause it to degrade over time. Therefore, it may get damaged.

Romex is made for indoor use only. Thus, it does not come with any protection against sunlight. Moreover, it uses a basic protective layer. The layer is not certified to protect from UV light.

UV light can damage the PVC jacket. The jacket can be damaged and cracked due to the UV rays and temperature. That is also a reason why it cannot be exposed to sunlight.

Can you run Romex on a covered patio?

You cannot run Romex on a covered patio. Romex cannot be used outdoors. So, you cannot use this in an exposed environment. Using it in an exposed environment means that the cable will be in a dry, wet, or corrosive environment, which is not suitable for it. 

It may damage the cable if you use it for a longer period in these environments.

If you run Romex on a covered patio, this means that you are using the cable in an open environment. But it is prohibited to use this cable in open environments. 

So if you run a Romex cable on a covered patio, you expose the cable to the open and cause it to endure outdoor-related damages.

What type of electrical wire is used outdoors?

There are multiple types of wire available in the market that can be used outdoors. Though the names are different, they are all the same type which is type UF.

You might ask which type of electrical wire is used outdoors. Here are some selected types of electrical wires that we think are great for using outdoors:

UF-B 12/2:

This is designed for underground and outdoor usage. It uses copper conductors. It has protection against sunlight, moisture, and fungus.

UF-B 10/2:

This electrical wire is specifically made for feeding power to outdoor pumps, lamps and other loads. It can be used for feeding power from one existing building to another. It is sunlight, moisture, and fungus resistant.

UF-B 14/2:

This electrical wire is almost similar to UF-B 10/2 and UF-B 12/2. It is also good for outdoor use.

UF-B 16/2:

This electrical wire is made for low voltage operations. Mainly used as lighting cable outside residential and commercial buildings.

18 AWG:

18 AWG is another low voltage electrical wire. It is popularly used for lighting outdoors. It has good protection against sunlight and wet environments.

Tough Rubber Cable Flex 3 Core:

This particular cable is one of the best possible outdoor cables with the best protection layer. It is used for lighting purposes, but it has a great outer protection layer which makes it different from others.

Final thoughts:

Romex cannot be used outside. As it uses a PVC jacket as protection, it is not adequate for outdoor uses and protects the core of the wire from wet and corrosive environments. Although there is a type of outdoor Romex called type UF, which cannot be said as actual Romex.