When determining volume allowances for device boxes, how should branch-circuit conductors that pass through the box without a splice be counted?

When assessing volume allowances for device boxes, branch-circuit conductors that pass through the box without making a splice are counted once. This practice is based on established code guidelines that efficiently simplify the calculations regarding how much space is required within the box for the conductors. Since these conductors are not creating any additional load or complexity in terms of splicing—where a more thorough assessment of space requirements would be necessary—they only need to be accounted for as a single entity. Understanding this principle helps in ensuring compliance with regulatory standards and proper installation practices, ultimately promoting safety and functionality in electrical systems.