What type of fittings are used in outdoor portions of metallic raceway systems according to code?

In outdoor portions of metallic raceway systems, non-threaded fittings are typically required according to the code. This requirement is primarily based on the need for these fittings to provide superior protection against environmental factors such as moisture, corrosion, and physical damage. Non-threaded fittings often include options like couplings, connectors, and junction boxes that ensure a secure, weather-tight seal, which is crucial for maintaining the integrity of the electrical system in outdoor applications.

While threaded fittings can be used in some indoor applications or specific scenarios, they may not provide the same level of protection outdoors, where exposure to the elements can lead to compromised connections over time. Plastic fittings are generally not suitable for metallic raceway systems as they do not offer the required strength or grounding properties. Electrical fittings is a broader category that encompasses a range of fitting types but does not specifically address the needs for outdoor metallic raceway systems under the code, thereby making non-threaded fittings the correct choice for this context.