Electrical Conduit and Their Uses
Conduits, integral parts of electrical installations, consist of tubes made of various materials with different characteristics. Their main objective is to safeguard electrical conductors against mechanical damage and environmental factors like corrosion. Additionally, conduits help limit the natural wear of the conductors.
The conduit’s main purpose is to ensure the safety of electrical wiring.
Conduit Construction: Electrical conduits are typically circular tubes available in different types. They are designed to accommodate electrical conductors in various facilities.
These conduits can be tubular and made of materials such as galvanized steel, stainless steel, aluminum, or non-metallic options like PVC. They come in flexible or rigid forms. In wet or hazardous areas, special conduits are required.
If there is a need to bend flexible electrical cables multiple times, adaptable conduits are preferred.
Metal Conduits
Electrical Metal Tube (EMT)
EMT, short for Electrical Metal Tube, is primarily made of steel (occasionally aluminum) and widely used in commercial and industrial buildings. Its popularity stems from its easy bendability and the ability to connect and protect cables in home and commercial electrical systems. EMT tubing is commonly bent using hand benders, hydraulic benders, or electric benders. Apart from electrical conductors, it is also used for various contact wires in industrial settings due to its high resistance and durability.
Applications:
Data systems and fire protection systems.
Intermediate Metal Conduit (IMC)
Developed as a thin-walled conduit alternative to Rigid Metal Conduit (RMC), IMC weighs approximately one-third less than RMC. It can be used in the same applications as RMC and is more commonly found in new installations. IMC can also serve as an equipment grounding conductor when installed with appropriate accessories. It requires special tools for cutting and threading pipes. IMC is designed to protect electrical cables in industrial facilities with high-risk exposure or corrosive environments.
Applications:
Industrial electrical installations in high temperatures.
Outdoor use in corrosive environments.
Rigid Metal Conduit (RMC)
RMC is a threadable conduit typically made of steel with a protective galvanized coating. Its purpose is to physically protect and route electrical conductors and cables. It can also function as an equipment grounding conductor with the right accessories. RMC is commonly used outdoors to provide protection against damage while offering structural support to electrical cables, panels, and equipment. It is suitable for all weather conditions and occupancy types.
Applications:
Outdoor protection from damage and structural support.
All weather conditions and occupancy types.
Flexible Metal Conduit (FMC)
Flexible Metal Conduit, also known as “Greenfield” or “flex,” was invented in 1902 by Harry Greenfield. FMC is characterized by its flexibility and mechanical strength, allowing it to be installed underground for protecting utilities from damage, tampering, and weather. It consists of a helically-wound corrugated strip of aluminum or steel, forming a hollow tube for cable pulling. FMC is commonly used for protecting electrical wiring in commercial and industrial buildings. The diameter of the tube can vary depending on the end application requirements.
Applications:
Short cable runs between a wall box and a motor or fixed appliance.
Dry indoor locations due to its lack of airtightness.
Cable protection sleeve.
Liquid-Tight Flexible Metal Conduit (LFMC)
LFMC is a specialized type of flexible metal conduit with a plastic liner and sealed fittings, ensuring watertightness. It is used in industrial and commercial settings for mechanically protecting wires and cables when installing EMT or rigid conduit would be impractical. LFMC is available in sizes ranging from 3/8 inches to 4 inches.
Applications:
Outdoor equipment installations like air conditioners.
Non-Metallic Conduits
Poly Vinyl Chloride (PVC)
PVC conduit is highly regarded for exterior applications due to its excellent electrical resistance and flame resistance. PVC conduits are lightweight, versatile, and available in various grades and thicknesses, similar to plumbing pipes. They are suitable for direct burial and above-ground installations. PVC conduits find wide usage in public lighting, residential, underground commercial, and industrial networks. They offer high resistance to abrasion, mechanical impact, and corrosion, making them ideal for construction projects. Rigid and flexible PVC conduit options are available.
Advantages:
Long usable life, high impact and abrasion resistance.
Non-conductive material.
Corrosion resistance and durability.
Lightweight and flexible, allowing adaptation to uneven terrain and supporting dynamic loads.
Low chances of damage during installation.
Non-Metallic Tube (NMT)
Non-Metallic Tube (NMT) is a flexible corrugated plastic conduit that is moisture-resistant and fire-resistant. It can be easily bent and installed using snap closure or glued plastic fittings. NMT is suitable for concealed installations and can be used within cinder block structures. It is commonly blue in color and referred to as “tube smurf,” named after the cartoon characters, the Smurfs. Non-metallic conduits offer versatility and can be used in interior and exterior locations for various applications like electrical, telephone cables, HVAC, refrigeration, landscape lighting, and more.
Applications:
Electrical, telephone cables, HVAC, and landscape lighting installations.
Locations exposed to sunlight and weather.
It’s important to note that electrical conduits serve different purposes and have specific applications depending on the type and materials used. The selection of the appropriate conduit is based on factors such as the environment, type of installation, and specific requirements of the electrical system.