Combination Box Assembly and Field Power Distribution

Combination boxes are the intermediate layer where power from main distribution is divided into usable points in the field. Providing an accessible energy point near machines, feeding temporary equipment and serving maintenance crews plugging in hand tools, these boxes multiply without a plan at most facilities. Contech designs and installs combination systems around the plant’s real usage needs.

Planning a combination system starts by establishing where power is actually needed in the field. Maintenance points, machine surroundings, loading areas and zones using temporary equipment are marked out. Box positions are set to minimise extension lead use; leads trailing across a plant are both a trip hazard and a source of voltage drop. Protection is built correctly in every combination box. Each socket group has its own circuit breaker, so a fault at one point does not take the whole box out of service. Residual current protection is mandatory; where hand tools and portable equipment are used, that protection is a matter of personal safety directly. Appropriate residual current sensitivity and discrimination are planned together with the main board. Environment governs box and socket selection. Wet or washdown areas take high IP ratings, outdoor locations UV-resistant enclosures, and impact-prone areas impact-resistant bodies. Industrial sockets are used in types conforming to current rating and pole count standards. Mounting height and door swing direction are set so the box is genuinely usable in the field. When supply cables are pulled from main or sub-distribution, cross-sections are calculated allowing for simultaneous use. Every box carries a label showing which board feeds it and the circuit number; that label tells you within seconds which breaker to look for during a fault. After installation, residual current devices are verified with both the test button and a test instrument, earth continuity is measured and the results reported.