A raceway (sometimes referred to as a raceway system) is an enclosed conduit that forms a physical pathway for electrical wiring. Raceways protect wires and cables from heat, humidity, corrosion, water intrusion and general physical threats.
A well-grounded metallic conduit provides RF (radio frequency) shielding that minimizes the risk of trouble with electromagnetic interference (EMI). In some systems, plastic conduit is sufficient. However, because it offers no electrical grounding or RF shielding, plastic conduit is used mainly to contain coaxial cables or other forms of cable that have their own RF shielding.