Electrical Conduit Types and Fittings

As an electrician or apprentice, the conduit will be your faithful companion throughout your career. Getting familiar with them can quickly ramp up your learning curve. But what exactly are the various electrical conduit types and fittings? We'll help you answer these questions in this Training Apprentice.

What is Electrical Conduit?

Typically, a pipe is a channel or pathway that can be applied in many different areas. Roads can be traffic pipelines, ditches can be water supply pipelines, and websites can be information pipelines.

When we talk about electrical conduit, we're talking about the physical pathways you create to run wiring through your building. They are used to guide and protect wiring.

You'll likely use several different types of conduit throughout your career, and you'll find specific details on how and when to use it in the National Electrical Code and other state and local building codes.

it's all about the pathway

The basic idea is that you create a logical path from the box to every point in the building that needs power, which is almost completely hidden once the walls and ceiling are in place. On the exterior of the building, in open ceiling structures, electrical rooms and elsewhere, there may be some pipes that are still visible.

After installing the electrical conduit paths, pull the wires through them to the termination point.

When you're talking about types of electrical conduit and terms like "rigid" and "flexible," you'll hear several acronyms. Here is a breakdown of the most common types of electrical conduit.

RMC: Rigid Metal Conduit

RMC stands for "Rigid Metal Conduit." It is one of the most durable types of electrical conduit and uses galvanized steel for its construction. As an outdoor friendly conduit, it provides excellent protection from environmental and physical damage. It is also capable of providing structural support for boxes, cables and other electrical equipment.

• Typical Fastening Method: Thread
• Common Sizes: 1/2″ – 2-1/2″
• Common Applications: Outdoor Installation

IMC: Intermediate Metal Conduit

The Intermediate Metal Conduit (IMC) is a slimmer version of the RMC, thinner and lighter. Although it is not as thick, it is generally approved for all the same applications as RMC. Given the choice between the two, our electrician preferred the IMC due to its lighter weight and easier handling.

• Typical Fastening Method: Thread
• Common Sizes: 1/2″ – 2-1/2″
• Common Applications: Outdoor Installation

EMT: Electrical Metal Tubing

On our Pro team, EMT is the term we use most when talking about types of electrical conduit. Some newcomers use it as a catchall term for all metal conduits, but that's not actually true.

EMT stands for "Electrical Metal Tubing" and is a rigid metal conduit. You'll usually see it made of galvanized steel, and in some cases aluminum as well.

As a thinner metal tube, it bends and kinks easily. When you install the EMT, you can use a conduit bender to bend it without kinks, all you need is a compact or 12V reciprocating saw with a high TPI blade to cut it.

• Typical Fastening Method: Compression
• Common sizes: 1/2″ – 1″
• Common Applications: Residential and light commercial interiors (outdoor use requires waterproof accessories)

FMC: Flexible Metal Conduit

Long before most of us were born (early 1900's), Harry Greenfield invented the Flexible Metal Conduit (FMC). It uses steel or aluminum for its structure and has a unique helical appearance that makes it easier to bend over short distances than EMT. It is a great advantage when you need to add conduit in tight spaces or around existing equipment.

• Typical Fastening Method: Thread
• Common Sizes: 1/2″ – 4″
• Common Applications: Indoor

LFMC: Liquid Tight Flexible Metal Conduit

LFMC, or liquid-tight flexible metal conduit, is similar to FMC but covered with a waterproof coating. It is suitable for outdoor applications and wet indoor areas where waterproof accessories are required.

• Typical Fastening Method: Thread
• Common Sizes: 1/2″ – 4″
• Common Applications: Outdoor and Indoor Wet Areas

ENT: Electrical non-metallic tubes

Electrical non-metallic tubing (ENT tubing) differs from the other types of electrical tubing we've discussed so far in several ways. This is a flexible PVC pipe that looks a lot like a pool hose.

You can wrap it in concrete, run it behind walls and under floors, and use it as an EMT replacement. The major manufacturers of ENT use 2-hour fire rating materials. However, ENT is not UV resistant, so it is not feasible to use it where it will be exposed to UV light.

• Typical fastening methods: snap lock or glue
• Common Sizes: 1/2″ – 2″
• Common Applications: Indoor

Rigid PVC Conduit

Due to its similarity to the PVC we use in plumbing and irrigation, rigid PVC is a very familiar material to many. Unlike an EMT, you cannot manipulate it with a conduit bender. PVC needs to be heated before it can be bent. Typically, this happens with a heat box, but you can use a heat gun on site as an alternative.

As a conduit, rigid PVC has the same properties as water pipes: it is glued together, and when properly installed it is watertight. This makes it useful for direct burial underground and is permissible in corrosive environments. You can also wrap it in concrete, hide it in a wall or leave it exposed.

• Typical Fastening Method: Glue
• Common Sizes: 1/2″ – 5″
• Common applications: outdoor, indoor, underground