What is the allowable ampacity of three 1/0 AWG XHHW-2 aluminum conductors installed in RMC?

To determine the allowable ampacity of three 1/0 AWG XHHW-2 aluminum conductors installed in rigid metal conduit (RMC), it is important to refer to the National Electrical Code (NEC) and applicable tables that list ampacities for conductors.

The ampacity of conductors can vary based on several factors, including the material of the conductor (in this case, aluminum), the type of insulation (XHHW-2), the number of conductors installed together, and the environment in which they are installed (like RMC).

Typically, ampacity values for single conductors can be found in NEC Table 310.16, which provides the ampacity of conductors based on their size and insulation type when installed in various conditions. For three conductors installed together in a raceway, we often apply a derating factor due to the heat generated by the conductors.

When looking at the ampacity of 1/0 AWG aluminum conductors with XHHW-2 insulation, it is generally listed around 130 amperes for a single conductor under typical conditions. However, considering that we're dealing with three conductors in a conduit, we apply the appropriate derating factors. The