You have a five foot section of this or similar mounted to the wall just above the floor?...cleaning the wires up is with a cable raceway.
I think there's a nomenclature issue here. That's a cable management duct (or ductway), not a raceway (ignoring that some mfgs/vendors call it a raceway). It's not intended for single conductor, single insulated wires. It is intended to make cables look neater, which is your application. Running an extension cord, CAT5, and DMX cable in it for five feet will be no problem. (Insert NEC language here about "permanently" installing an extension cord, i.e. affixed to building.)
I've run CAT5 (carrying MA-net) for 300' alongside three sets of 4/0 feeder on the floor with no issues.