Some of the requirements and ratings include: voltage, continuous current, wire range (load and line side), short-circuit current rating or withstand rating (SCCR), type of upstream overcurrent protective device (fuse or circuit breaker) and spacing (between uninsulated live part. Some of the requirements and ratings include: voltage, continuous current, wire range (load and line side), short-circuit current rating or withstand rating (SCCR), type of upstream overcurrent protective device (fuse or circuit breaker) and spacing (between uninsulated live part. When applying Power Distribution Blocks (PDBs), there are various requirements that shall be satisfied, based upon different UL Standards, the NEC®, and the specific application. Some of the requirements and ratings include: voltage, continuous current, wire range (load and line side). 1. This specification. Fundamental Distinction: Terminal boxes utilize structured terminal blocks for organized, accessible connections and frequent maintenance, whereas junction boxes protect permanent wire splices and are rarely accessed after installation. Code Compliance: Both enclosures must adhere to NEC Article. The ready-to-connect FIX distribution blocks are available in different cross-sections, numbers of connections, mounting types, and colors.