CSLB C-10 Electrical ContractorWiring Methods and MaterialsMedium
An electrician is installing a new solar array on a rooftop. The DC wiring from the PV modules will run in conduit across the roof. The local Authority Having Jurisdiction (AHJ) requires that all conduit be suitable for direct sunlight exposure and extreme temperature variations. Which of the following conduit types is generally NOT suitable for direct outdoor exposure to sunlight and temperature extremes without special considerations or coatings?
- ARigid Polyvinyl Chloride Conduit (PVC) Schedule 80
- BElectrical Metallic Tubing (EMT)
- CRigid Metal Conduit (RMC)
- DIntermediate Metal Conduit (IMC)
Show answer & explanationAnswer & explanation
Correct answer: B. Electrical Metallic Tubing (EMT)
Electrical Metallic Tubing (EMT) is generally not listed for direct outdoor exposure to sunlight and temperature extremes without specific UV-resistant coatings or being encased in concrete. Its thinner wall and slip-joint connections are more susceptible to expansion/contraction issues and corrosion in harsh outdoor environments compared to RMC, IMC, or Schedule 80 PVC, which are designed for such conditions.
Why the other options are wrong
- A. PVC Schedule 80 is specifically designed for outdoor exposure and is UV resistant, making it suitable for direct sunlight.
- C. RMC is robust and suitable for direct outdoor exposure, including sunlight and temperature extremes.
- D. IMC is also robust and suitable for direct outdoor exposure, similar to RMC.
Outdoor Conduit Suitability
The suitability of conduit for outdoor exposure depends on its material, thickness, and resistance to environmental factors like UV radiation, corrosion, and temperature fluctuations.
- Metal conduits like RMC and IMC are generally robust for outdoor use.
- PVC conduit needs to be UV resistant (like Schedule 80) for direct sunlight exposure.
- EMT is typically not suitable for direct exposure to weather unless specifically listed for it or protected.
Memory trick: Outdoor conduit, sun and rain, choose wisely, avoid the pain!