NM Cable vs Shielded Cable

If you are considering wiring your home, you will have several options for what type of wire to use and how to protect it.

 However, two of the most popular options are NM cable and shielded cable. 

Both types of cable are very popular with DIYers because they are easy to work with and can be used in many applications with no metal conduit (if allowed by building code and inspectors).

NM cable

NM cable stands for non-metallic cable and is a fully self-contained electrical wiring product. The cable often has three wires (positive, neutral, and ground) enclosed in a hard plastic or rubber jacket.

 It is relatively inexpensive and extremely easy to work with. Although it is sometimes installed inside conduit, most people choose NM cable because of its flexible, self-contained sheathing. 

Generally , NM cable is run through studs and walls with no additional protective covering and is fine for many types of residential applications.

NM cable (which is also commonly known as Romex) is primarily used to connect new switches and sockets in a home or during a remodel project. 

I have used rarely it in the construction of new houses; However, there are signs that more and more contractors are using NM cable in the few cities and municipalities where building inspectors allow it.

 This is due we encase to its relatively low price compared to wiring that in metal conduit. Installing NM or Romex cable is also much faster than working with individual conduit and cables.

 

The areas that limit the use of NM cable do so for some very interesting reasons.

 Although the newer types of NM cable have proven to be more resistant to heat and damage, many brands of cable are still susceptible to damage from high temperatures or nicks during installation.

 In the event of a fire, NM cable burns and disintegrates quickly, which could cause an electric arc or sparks that could create a potentially even more deadly fire hazard.

Shielded cable

Like NM cable, shielded cable is also a flexible and self-contained electrical wiring solution. 

However, the shielded cable is encased in a type of flexible metal sheath. 

Because it is clad in metal, shielded cable is considered more durable and resistant to damage than NM or Romex cable. 

However, shielded cable is a bit more difficult to work with and may require specialized tools in some applications. 

While many people choose to cut armored cable with a hacksaw, it has shown this to not be the best way to cut cable. 

Cutting armored cable with a hacksaw has nicked the wiring, which could cause a potential fire hazard. Shielded cable is also considerably more expensive than NM cable.

Many cities and municipalities now allow for the use of shielded cable in most commercial and residential applications. 

While I can use NM cable in some residential remodeling projects, shielded cable is now accepted in almost as many constructions by city planning offices and local building inspectors.

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