Learn what OSHA requires for temporary wiring on construction sites, from grounding and GFCI protection to overhead clearances and employer liability. These federal rules, enforced by. Flexible cords used with temporary and portable lights shall be designed for hard or extra-hard usage. work requires electrical power for many purposes. However, exposure to weather, frequent relocation, rough use and other condi-tions not normally encountered with conventional wiring systems necessitate special consideration not require in other applications or in completed structures. According to IEC, IEC 60529 defines the IP rating system for protection against dust and water ingress.