Understand the interface decision

A route that appears spacious on a plan can contain a tightly grouped duct section or a shared trench crossing. These local conditions can control the thermal design. Soil thermal assumptions and depth also matter; a catalogue rating may be based on a different installation.

Cable selection joins electrical performance, installation conditions and termination requirements. A calculation for one purpose does not settle the others. Keep the actual route and equipment interface attached to the design review, so later changes remain visible.

Put these inputs in the review record

Use a project-specific worksheet to capture the following information. For each entry, name the document, revision and person responsible for resolving any uncertainty.

• Trench and duct arrangement along each route segment. Identify the exact configuration and the supporting document.
• Simultaneous loading of neighboring circuits. Keep the design assumptions visible in the project record.
• Ground conditions and thermal assumptions used in the calculation. Name the responsible reviewer and resolve any missing information.
• The cable-rating method and any applicable grouping adjustments. State how this entry will be verified during acceptance.

Define the acceptance boundary

Use the most relevant installation conditions in the design assessment and preserve the route segments that control the rating. A later addition to the trench should trigger a grouping review rather than assuming spare physical space means spare thermal capacity.

The deliverable should connect the calculated current limit to the actual route drawing. This makes it possible to evaluate future cables or changed operating patterns without rebuilding the design assumptions from memory.