Which type of conduit is NOT typically used for traffic signals?

The type of conduit that is not typically used for traffic signals is flexible rubber conduit. In traffic signal installations, the conduits must provide strong protection against environmental factors and mechanical damage, along with the ability to house electrical wiring safely.

Rigid steel conduit is preferred for its durability and strength, particularly in outdoor environments where it may be subjected to impacts and weather. High-density polyethylene (HDPE) is also used for its lightweight properties and resistance to corrosion, making it suitable for underground installations. PVC Schedule 40 is commonly used due to its ease of installation, resistance to chemicals, and low cost, making it a typical choice for many electrical systems, including traffic signals.

On the other hand, flexible rubber conduit is generally not used in traffic signal applications because it does not provide the same level of protection as rigid conduits. Additionally, it may not be as suitable for permanent installations where stability and durability are crucial. Its flexibility is beneficial in certain situations, such as temporary wiring or areas requiring adaptability, but these characteristics do not align with the requirements and standards for traffic signal infrastructure.