First, fix the distribution box or panel using an iron frame. Whether you are an electrical contractor or a construction brigade, knowing how to properly and safely install distribution boxes is the basis of ensuring the safe operation of the entire system. more DISTRIBUTION ELECTRICAL CABINET CONNECTION PROJECT. However, the key to. ype, a “R” is added after the Specification. A paid repair will be provided if the warranty period expires. Whether it is residential buildings, commercial facilities or industrial sites, the.