Which wiring methods are permitted for service entrance conductors?

Service entrance conductors must be installed using wiring methods that ensure safety, durability, and compliance with the National Electrical Code. All of the options presented are acceptable methods for conducting electrical service to a building.

Open wiring on insulators is one traditional method that allows for the installation of wires without any enclosing conduit. This technique is still used in specific applications, such as rural areas or for overhead service drops where suitable insulation and support are provided to protect the wires.

Type IGS (Insulated Grounded Service) cable is specifically designed for service entrance applications. It has factory-installed insulation and can be direct buried or installed above ground, providing excellent protection against environmental factors while ensuring electrical safety.

Rigid metal conduit (RMC) is another reliable method for protecting service entrance conductors. It provides robust mechanical protection and is corrosion-resistant, making it suitable for various installation conditions. RMC can be used in exposed locations and offers additional grounding benefits.

Given that each option represents a legitimate method of installation under the NEC for service entrance conductors, the correct answer encompasses all methods listed, thus confirming that all are permissible.