There are many different factors to consider when determining the required dimensions of a wire harness. Pre-design measurements should include:
Wire ends include strip length, terminal type, terminal and terminal coating, connection points, and connector design.
Voltage/current requirements (Type of conductor, size of conductor)
Sheath material (usually made of hard plastic, PVC, TPE, PU or PTFE).
Length and tolerance of wire (must be long enough for the bend radius, should also reach the connector) and ability of wire to stand up over time
These guidelines can also be applied to multi-conductor cables, which are similar to wire harnesses, but provide more robust protection. They are generally less cost effective, but can withstand extreme physical conditions.