Last Updated on April 23, 2023 by Electricalvolt
The most significant function of electrical conduits is to protect and support electrical cables so that they do not cause potential hazards or internal damage.
Conduits are an integral part of any electrical installation. Electrical conduits are essential tubes made of different materials and characteristics whose main objective is to protect the electrical conductors from any damage. The damages may be due to mechanical or derived from the action of other environmental agents, such as corrosion. The conduits also generally limit the natural wear of the conductors.
The main purpose of conduit is to safeguard the electrical wiring.
Construction of conduits
The electrical conduits are tubes that are circular cross-sections of different types. They are intended for the accommodation of electrical conductors in the facilities.
It is usually tubular and made of metal such as galvanized steel, stainless steel, aluminum, or non-metallic materials such as PVC, and is either flexible or rigid. Special types of conduits are required in wet areas and hazardous areas.
Adaptable conduits are preferred if flexible electrical cables have to be bent several times.
- Electrical Metal Tube (EMT)
- Intermediate Metal Conduit (IMC)
- Rigid Metal Conduit (RMC)
- Flexible Metal Conduits (FMC)
- Liquid-Tight Metal Conduit (LTMC)
- Non-Metallic Tube (NMT)
Types of Metal Conduit
1. Electrical Metal Tubes (EMT)
Electrical metal tubes, known on the market by the abbreviation “EMT” are made of steel (in some cases aluminum is also used as the main component). EMT conduit is a very popular material in commercial and industrial buildings.
This is the main reason that it can be easily bent/oriented within a certain radius or in specific directions. Hand benders, hydraulic benders, and electric benders are used to bend electrical metal tubes in the field. In the case of EMT tubing, they are used to connect and protect cables for home and commercial electrical systems.
Metal tubes were invented to protect electrical conductors in the most efficient way possible. Today it is used not only for electrical conductors but also for all kinds of contact wires, especially in the industrial field due to its great resistance and durability.
It is used for data systems and wiring systems against fire, having a special route in the case of systems against fire.
2. Intermediate Metal Conductors (IMC)
Intermediate metal conduit (IMC) was developed in the year 1970s as a thin-walled conduit alternative to Rigid Metal Conduit (RMC). It weighs approximately one-third less. IMC is the thinner, lighter version of RMC and is approved for use in the same applications as RMC. These tubes are more common in new installations.
It may be used as an equipment grounding conductor when installed with associated couplings and appropriate accessories. Requires special tools to cut pipe and threads.
The IMC conduit tube is designed to protect electrical cables in industrial facilities in classified areas of high risk of exposure, and in areas with corrosive environments. Since this type of tube is resistant to any damage or metallic blows compared to other materials like plastic or iron. In addition, the conduit can be threaded.
- Industrial electrical installation in high temperatures.
- Used outdoors, where its anticorrosive characteristics will allow its correct operation for many years.
- It is specifically designed to guard insulated cables and conductors.
3. Rigid Metal Conduit (RMC)
A rigid metal conduit (RMC) is typically made of steel with a protective galvanized coating. It is a threadable conduit designed to physically protect and route electrical conductors and cables. It is used as an equipment grounding conductor when installed with the appropriate accessories.
It is typically used outdoors to protect from damage and can provide structural support for electrical cables, panels, and other equipment.
It can be used in all weather conditions and forms of occupancy.
4. Flexible Metal Conduit (FMC)
In honour of its invention in 1902 by Harry Greenfield, a flexible metal conduit (FMC) is called “Greenfield” or popularly “flex”.
Due to its flexibility and mechanical strength, the flexible conduit can be installed underground to protect utilities from damage, tampering, and weather. Flexible conduits are very useful and offer several safety features such as corrosion, flame, and water resistance.
A flexible metal conduit (FMC) is manufactured by helically winding a corrugated strip of aluminum or steel, forming a hollow tube through which cable can be pulled. In commercial and industrial buildings, the FMC protects electrical wiring.
The diameter of this tube can vary and different end applications require tubes of different diameters.
- The cable is typically used for short runs between a wall box and a motor or fixed appliance.
- It is recommended for dry indoor locations because it is not airtight.
- Flexibility and light weight make it easier to install than a rigid conduit.
- A flexible metal conduit is a spiral metal sleeve, generally used as a cable protection sleeve.
5. Liquid-Tight Flexible Metal Conduit (LFMC)
It is a special type of flexible metal conduit with a plastic liner and sealed fittings to make it watertight. Liquid tight flexible conduit is designed and used in most industrial and commercial settings for the mechanical protection of wires and cables where it would be impractical to install EMT or rigid conduit.
Flexible metal corrugated PVC conduit is available in commercial sizes from 3/8 inches to 4 inches.
Liquid Tight Flexible Metal conduit is usually used in conjunction with outdoor equipment like air conditioners.
Types of Non-metallic conduits
1. Poly Vinyl Chloride (PVC)
It has very good electrical resistance and flame. PVC conduit is considered the best for exterior applications. Among all types of tubes, PVC is lightweight and versatile. Various grades and thicknesses are available, which is similar to plumbing pipe. The PVC conduit is suitable for direct burial as well as above-ground installation.
The PVC conduit pipe is ideal for housing and protecting electrical wiring in public lighting, and residential, underground commercial, and industrial networks. The PVC pipe conduit has a high resistance to abrasion, good mechanical resistance, and impact, which makes it common and ideal for buildings and construction. It is available in two forms.
- Rigid PVC conduit
- Flexible PVC conduit
- This material has a great advantage over any other material used for pipes.
- Long usable life, high resistance to impact and abrasion.
- It does not conduct electricity.
- Corrosion resistance and higher durability.
- It is light in weight and flexible, adapting to uneven terrain and supporting dynamic loads, which leads to its low-cost ease of installation.
- Chances of being damaged are low when it comes to the moment of installation or relation of the system.
2. Non-metallic Tube (NMT)
Non-metallic electrical (NMT) conduit is a flexible corrugated plastic conduit that is moisture-resistant and fire-resistant. It is easy to bend and install with snap closure or glued plastic fittings. NMT can be installed inside cinder block structures and can be concealed. A common brand color of this conduit is blue. The non-metallic tube (NMT) is nicknamed “tube smurf”, after the cartoon characters of the Smurfs.
Non-metallic conduits are versatile and can be used in various interior and exterior locations. It is used for utility patch cords, data centers, electrical signals and outdoor lighting, HVAC, and other locations exposed to sunlight and weather.
It is commonly known as
- NM Liquid Tight Flexible Conduit
- Non-Metallic PVC
- Flexible PVC
- PVC Electrical Conduit.
It is ideal for employing in multiple applications, including electrical, telephone cables, HVAC, refrigeration, landscape lighting, and more.