The number of cores which can be joined is limited by the number of holes/screws in each terminal - these can vary from 2 to 6. A problem when purchasing Junction Boxes is to know which type of terminal is fitted and, where Bus Bars are fitted, how many cable. This guide helps you determine the correct dimensions based on wire fill capacity, device requirements, and installation environment, ensuring a safe and efficient electrical system. Selecting the appropriate junction box size prevents overcrowding, overheating, and potential hazards. This count includes each conductor. Outline the steps for calculating the required **minimum physical size** of an electrical JB. 28, and they apply to all conductors 4 AWG and larger (Fig.