Conduit is a vital component of electrical systems, protecting wires and cables from damage and ensuring their proper functioning. To maintain the integrity and safety of electrical installations, it is crucial to provide adequate support for conduit systems. This article delves into the specific requirements for supporting different types of conduit, as outlined by the National Electrical Code (NEC) and other relevant sources.
Key Facts
- Rigid Metal Conduit (RMC): According to the National Electrical Code (NEC), RMC must be supported at least every 10 feet.
- Electrical Metallic Tubing (EMT): EMT should be securely fastened in place at least every 3 meters (10 feet). Horizontal runs of EMT supported by openings through framing members should be securely fastened within 900 mm (3 feet) of termination points.
- Non-Metallic Sheathed Cable (NM Cable): NM cable must be supported and secured every 4.5 feet and within 12 inches of every outlet box, junction box, cabinet, or fitting.
- Metal-Clad Cable (MC Cable): MC cable must be secured at intervals not exceeding 6 feet and supported every 6 feet. However, there are exceptions where MC cable may be unsupported in certain situations.
- Rigid Polyvinyl Chloride Conduit (PVC Conduit): PVC conduit must be secured within 3 feet of each outlet box, junction box, device box, conduit body, or other conduit termination. The support distance varies based on the size of the conduit.
Rigid Metal Conduit (RMC)
According to the NEC, RMC must be supported at least every 10 feet. This requirement ensures that the conduit is adequately secured and prevents sagging or drooping, which can lead to damage to the conduit and the wires it contains.
Electrical Metallic Tubing (EMT)
EMT should be securely fastened in place at least every 3 meters (10 feet). Additionally, horizontal runs of EMT supported by openings through framing members should be securely fastened within 900 mm (3 feet) of termination points. These requirements ensure that EMT is properly supported and secured, minimizing the risk of movement or damage.
Non-Metallic Sheathed Cable (NM Cable)
NM cable, commonly used in residential and commercial buildings, must be supported and secured every 4.5 feet and within 12 inches of every outlet box, junction box, cabinet, or fitting. This requirement ensures that NM cable is adequately supported and secured, preventing sagging or drooping that could compromise its integrity.
Metal-Clad Cable (MC Cable)
MC cable must be secured at intervals not exceeding 6 feet and supported every 6 feet. However, there are exceptions where MC cable may be unsupported in certain situations, such as when fished through concealed spaces in finished buildings or when not more than 6 feet in length from the last point of cable support to the point of connection to a luminaire or other equipment. These requirements ensure that MC cable is properly secured and supported, minimizing the risk of movement or damage.
Rigid Polyvinyl Chloride Conduit (PVC Conduit)
PVC conduit must be secured within 3 feet of each outlet box, junction box, device box, conduit body, or other conduit termination. The support distance varies based on the size of the conduit, with larger conduits requiring more frequent support. These requirements ensure that PVC conduit is adequately supported and secured, preventing sagging or drooping that could compromise its integrity.
References
- California Code of Regulations, Title 8, Section 2761. Rigid Metal Conduit. (https://www.dir.ca.gov/title8/2761.html)
- Supporting EMT. (https://forums.mikeholt.com/threads/supporting-emt.108446/)
- Securing & Supporting Cables & Raceways Part Two. (https://www.jadelearning.com/blog/securing-and-supporting-cables-and-raceways-2/)
FAQs
What is the general requirement for supporting conduit?
Conduit systems must be adequately supported to prevent sagging or drooping, which can compromise the integrity of the conduit and the wires it contains.
How often should Rigid Metal Conduit (RMC) be supported?
RMC must be supported at least every 10 feet, as specified by the National Electrical Code (NEC).
What are the support requirements for Electrical Metallic Tubing (EMT)?
EMT should be securely fastened in place at least every 10 feet, and horizontal runs of EMT supported by openings through framing members should be securely fastened within 3 feet of termination points.
How often should Non-Metallic Sheathed Cable (NM Cable) be supported?
NM cable must be supported and secured every 4.5 feet and within 12 inches of every outlet box, junction box, cabinet, or fitting.
What are the support requirements for Metal-Clad Cable (MC Cable)?
MC cable must be secured at intervals not exceeding 6 feet and supported every 6 feet. However, there are exceptions for certain situations, such as when fished through concealed spaces or when the length is less than 6 feet.
How often should Rigid Polyvinyl Chloride Conduit (PVC Conduit) be supported?
PVC conduit must be secured within 3 feet of each outlet box, junction box, device box, conduit body, or other conduit termination. The support distance varies based on the size of the conduit.
What are some common methods for supporting conduit?
Common methods for supporting conduit include using straps, clamps, hangers, and brackets. The specific method used will depend on the type of conduit and the installation environment.
Why is it important to properly support conduit?
Properly supporting conduit ensures that the conduit and the wires it contains are protected from damage due to sagging or drooping. It also helps to maintain the integrity of the electrical system and prevent potential hazards.