Length Limitations of Flex Conduit:

The National Electrical Code (NEC) generally does not impose a specific length limitation on flex conduit. However, there are certain exceptions where length restrictions apply:

Lighting Fixtures

For lighting fixtures, the NEC limits the length of flex conduit to 6 feet to minimize the ground return path. This restriction aims to ensure proper grounding and prevent potential electrical hazards.

Motor Leads

The NEC also limits the length of motor leads between the motor and the required junction box to a maximum of 6 feet, regardless of the type of conduit used. This limitation is in place to maintain proper motor operation and prevent overheating or damage to the motor.

Grounding

If the length of flex conduit exceeds 6 feet, an equipment grounding conductor must be used. This is to ensure a continuous and effective grounding path, reducing the risk of electrical shock and ensuring the safety of the electrical system.

Support and Grounding Requirements for Flex Conduit

When using flex conduit, it is crucial to follow the NEC rules for support and grounding:

Support

Flex conduit must be supported within 12 inches of any conduit termination and at intervals not exceeding 4.5 feet for lengths over 6 feet. This is to prevent sagging, kinking, or damage to the conduit, which could compromise its integrity and safety.

Grounding

If flex conduit is used for grounding, it must be listed for grounding, and the length is limited to 6 feet. If a separate grounding conductor is provided, the length of the flex conduit is not limited. This ensures proper grounding and minimizes the risk of electrical hazards.

References

1. Lengths and Limitations for FMC and LFMC
2. Does the NEC Limit a Flexible Metal Conduit Run?
3. Flexible Metal Conduit Length?

FAQs

Is there a general length limitation for flex conduit?

In general, the NEC does not impose a specific length limitation on flex conduit. However, there are certain exceptions and specific cases where length restrictions apply.

What is the length limitation for flex conduit used with lighting fixtures?

For lighting fixtures, the NEC limits the length of flex conduit to 6 feet to minimize the ground return path and ensure proper grounding.

Is there a length limitation for motor leads using flex conduit?

Yes, the NEC limits the length of motor leads between the motor and the required junction box to a maximum of 6 feet, regardless of the type of conduit used. This is to maintain proper motor operation and prevent overheating or damage.

What are the support requirements for flex conduit?

Flex conduit must be supported within 12 inches of any conduit termination and at intervals not exceeding 4.5 feet for lengths over 6 feet. This is to prevent sagging, kinking, or damage to the conduit, ensuring its integrity and safety.

Are there any grounding requirements for flex conduit?

If flex conduit is used for grounding, it must be listed for grounding, and the length is limited to 6 feet. If a separate grounding conductor is provided, the length of the flex conduit is not limited. This ensures proper grounding and minimizes the risk of electrical hazards.

Can flex conduit be used in wet or outdoor locations?

Flex conduit can be used in wet or outdoor locations if it is listed for such use. It is important to choose a flex conduit that is resistant to moisture and sunlight to ensure its durability and safety in these environments.

What are some common applications of flex conduit?

Flex conduit is commonly used in various applications, including connecting lighting fixtures, motors, and other electrical equipment, providing flexibility and ease of installation in tight spaces or where movement is required. It is also used in temporary wiring installations, such as construction sites or trade shows, due to its flexibility and ease of removal.