Table of Contents
The Complete Guide to Conduit Fittings
Conduit fittings support the safety and reliability of electrical systems. They protect conductors from damage, provide secure connections and ensure proper routing in outdoor and indoor settings. The correct choice and use of components ensures compliance and system longevity.
Discover what a conduit is, conduit fitting types and how to select the right solution.
What Is a Conduit and Why Are Fittings Important?
An electrical conduit is a protective tube constructed from steel, aluminum, polyvinyl chloride (PVC) or liquid-tight components that routes and safeguards electrical wiring. Conduit fittings extend the conduit’s protective function to every bend and termination.
Conduit fittings are beneficial for:
- Protecting wires: Conduits prevent wires from being cut, crushed or abraded.
- Safety: Electrical conduits contain sparks or short circuits, helping reduce the risk of fire or accidental contact with live wiring.
- Organization: By providing pathways for routing multiple conductors across layouts, conduits support system organization.
- Compliance: The National Electrical Code (NEC) specifies fittings for conduit types, materials and locations. Using the proper type ensures compliance.
Types of Conduit Fittings
There are several types of electrical conduit fittings. Each type is manufactured with different materials and is suited for specific applications.
Couplings
Couplings extend conduit runs by joining two sections together. Common types include:
- Rigid couplings are heavy-duty fittings made from galvanized steel or aluminum. They can be threaded or threadless and are used in industrial and outdoor environments.
- Electrical metallic tubing (EMT) couplings are available in compression or set-screw designs made from zinc die-cast or aluminum. These are used in commercial and indoor settings.
- Intermediate metal conduit (IMC) couplings are threaded fittings made from steel or aluminum. They strengthen installations in commercial and industrial settings.
- Liquid-tight conduit fittings are constructed from galvanized steel, PVC, aluminum or stainless steel. They are best suited for wet or hazardous settings to prevent moisture ingress.
Connectors
Connectors attach conduit to boxes, enclosures or panels for secure terminations. They include:
- Set-screw connectors are fittings made from zinc die-cast or steel, and are used with EMT conduits in dry locations.
- Compression connectors are made of galvanized steel, aluminum or nickel-plated brass and provide a vibration-resistant seal. They are used indoors and outdoors to provide a watertight connection.
- Threaded connectors are made from steel, nickel-plated brass or PVC, and are paired with rigid and IMC conduits for secure grounding and toughness.
- Liquid-tight connectors feature gaskets and seals made from nickel-plated brass, zinc or coated steel. They are used in heating, ventilation and air conditioning (HVAC) systems, mining and industrial applications.
Elbows
Elbows allow conduits to change direction around obstacles or corners, and are available in steel, aluminum or PVC.
Common ones include:
- 45-degree elbows provide a smoother directional change. They are used in HVAC for routing around obstacles. In industrial settings, they guide conduits around machinery and equipment.
- 90-degree elbows provide a sharp directional change and are commonly used in tight spaces such as utility rooms or around structural elements.
Bushings
Bushings protect wires from abrasion and assist with grounding. Primary ones include:
- Insulated bushings are made from thermoplastic, zinc die-cast or polyethylene and protect wires from abrasion during installation and operation. They are used in fiber-optic and cable assemblies to prevent cable damage.
- Grounding bushings are constructed from steel or malleable iron and provide a secure path for bonding metallic conduit to the ground.
Locknuts
Locknuts secure fittings to boxes and enclosures. You will encounter two types:
- Standard locknuts are made from steel, nickel-plated brass or aluminum and provide basic mechanical fastening for metallic conduits.
- Grounding locknuts are designed from steel and ensure fastening and reliable electrical bonding.
Unions
Unions allow conduit sections to be joined in locations with limited rotation. Common options include:
- Rigid unions are threaded fittings manufactured from steel, galvanized steel or aluminum. They provide secure connections with rigid conduit systems in commercial and industrial applications and areas with hazardous materials.
- EMT unions are available in set screw or compression designs. They are used in indoor residential and commercial installations to provide a pathway for electrical wiring and protect it from damage.
- IMC unions are threaded steel fittings, and they are designed for IMC. They are installed in industrial buildings to protect electrical systems in factories and manufacturing plants.
Reducers
Reducers connect conduits of different sizes. These include:
- Concentric reducers are cone-shaped fittings made from galvanized steel, stainless steel or carbon steel. They align the centerlines of two different conduit sizes and maintain a symmetrical system layout. They are used in HVAC systems, water lines, drainage and pump suction lines.
- Eccentric reducers are made of steel, carbon steel or PVC and offset the bottom alignment of conduits. You will find them in HVAC systems, chemical processing plants or slurry pipelines.
Other Fittings
Additional fittings support specialized needs in conduit installations. Popular options include:
- Caps seal and protect conduit ends or openings. They are made from metal or plastic and maintain the integrity of electrical systems by preventing short circuits, electrical fires and equipment damage.
- Nipples are short threaded conduit sections, and they are used to connect enclosures or boxes placed in close proximity. They are made of galvanized steel or PVC, and they help create a continuous and secure raceway for wiring.
Selecting the Right Conduit Fitting
Choosing the correct fitting requires consideration of conduit type, location, code requirements and the intended application.
Conduit type
Each conduit type dictates which fittings can be used. Consider the following:
- EMT requires set screw or compression connectors to complement indoor commercial applications.
- Rigid metallic conduits pair with threaded steel or aluminum fittings to support durability for outdoor and industrial use.
- IMC works in tandem with threaded fittings similar to rigid ones for strength.
- PVC requires solvent-cement or threaded adapters for protection in underground or corrosive environments.
- Liquid-tight conduit requires gasketed fittings to ensure a sealed system in wet and high-vibration settings.
Environmental Conditions
Environmental conditions influence the material choice and sealing requirements.
Wet locations require liquid-tight or PVC-coated fittings to prevent moisture intrusion, while corrosive environments require stainless steel or PVC-coated fittings to protect connections from chemical reaction damage. Dry environments benefit from EMT set-screw or compression fittings for reliable performance.
Code Compliance
NEC standards specify which fittings installers should use with each conduit type. Local requirements may add additional restrictions, and these rules often account for unique environmental or safety considerations. Adherence to codes ensures system safety, grounding continuity and fire protection.
Application
Application-specific needs should always be matched with the correct fitting style to maintain safety and efficiency.
Connecting conduit sections requires couplings and unions to ensure mechanical continuity.
When routing around obstacles, add elbows to maintain conductor integrity during directional changes. Terminating conduit runs requires bushings, locknuts and connectors for safe and code-compliant endpoints.
Installation Tips and Best Practices
Even the best conduit fittings cannot perform as intended without proper installation. Using installation guides helps installers stay compliant and achieve optimal performance. Here are five best practices for long-term reliability:
- Planning and measurement: Map every conduit run in advance and identify potential obstacles before installation. Cut conduits to precise lengths, and deburr edges to protect conductors.
- Connection: Clean all threads and surfaces before tightening for proper bonding and electrical continuity.
- Securing: Secure locknuts, bushings and connectors firmly and tighten to manufacturer specifications. Install support straps and hangers at recommended intervals to prevent sagging and system strain.
- System flexibility: Use expansion joints in outdoor runs to allow for thermal movement. Incorporate nipples and unions where disassembly or modifications will be required.
- Compliance: Verify installations against NEC, the National Electrical Contractors Association (NECA) and local code requirements. Follow the manufacturer’s instructions closely.
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