Final answer:
To find the maximum number of #14 AWG RW90XLPE conductors in a 21-mm conduit as per the NEC, one must refer to the conduit fill tables in NEC Chapter 9, Table 1. This determines the allowed number of conductors based on the conduit size and conductor size, essential for proper heat dissipation and ease of wire pulling.
Step-by-step explanation:
The question asks for the maximum number of #14 AWG RW90XLPE, 1000-V, unjacketed conductors that can be placed in a 21-mm conduit as dictated by the National Electrical Code (NEC). To determine this, we need to refer to the conduit fill tables provided by the NEC. The number of conductors permitted is based on the conductor size and the conduit diameter to ensure there is enough space for heat dissipation, avoidance of conductor insulation damage, and ease of pulling the wires through the conduit.
The NEC provides tables that include the types of conductors and the percentage fill of the conduit they are allowed. For a 21-mm conduit diameter and #14 AWG conductors, you would reference these tables to find the permissible number of conductors. The exact value can vary depending on the specific amendments to the NEC and local codes that might affect the permitted fill percentages.
To find the precise number without the NEC tables at hand would be speculative. However, these tables are found in NEC Chapter 9, Table 1, and notes to Tables, which provide the percentage fill for various types of conduits and conditions. It's recommended to consult the latest version of the NEC or a professional electrician to ensure compliance with current standards.