Why reserve raceway capacity?
A shared raceway can have physical space that is neither occupied today nor intended to remain completely unplanned. Explicitly reserving a portion for future work makes expansion planning visible instead of accidentally consuming every available space.
Core calculation
Free capacity = total planning capacity − current used capacity − future reserve.
The page also converts each quantity into a percentage of the entered planning capacity. The reserve is not treated as current occupancy; it is intentionally held aside for a future purpose.
Worked example
If the planning capacity is 100 units, current use is 55 and future reserve is 25, the model shows 55% current use, 25% reserved capacity and 20% free capacity.
Why this is different from raceway sizing
The tool does not determine the raceway's physical or code-compliant capacity. It accepts a capacity reference that has already been established elsewhere. Its purpose is allocation and reservation within that reference.
Decision support
A positive free-capacity value means your entered reserve can coexist with current allocation in the model. A negative value means your current use plus intended reserve exceeds the entered planning capacity and the allocation needs revision.
Limitations and safety
Raceway capacity may depend on conductor count, size, geometry, temperature, installation method and applicable requirements. Never interpret this percentage model as a code-compliance calculation.
Frequently asked questions
Can future reserve be zero?
Yes. Enter zero when no specific future capacity is being held aside.
Does reserved capacity mean empty physical space?
Not necessarily. It means capacity intentionally allocated for future planning within the model.
Can the result show negative free capacity?
Yes. That flags an over-allocation of current use plus future reserve relative to the entered reference capacity.