Sunlight-Resistant Conductors for Electrical Installations
When most man-made objects are placed in direct sunlight, they may deteriorate in color, strength and flexibility. Depending on the thickness, the hardness and the chemical complexity, we can slow the deterioration rate of our structures and networks. And this requires our electrical conductors to be sunlight resistant to ensure their long-term safety.
The Canadian Electrical Code 2-134 (2015) makes a requirement that electrical wiring and non-metallic conduits that are exposed to direct sun rays be specifically approved for exposure to sunlight. And this requirement is for communication cables as well.
Notice the service conductors for this commercial building are protected by PVC conduits underground and then metal conduit above ground (Edmonton, AB).
Prevent the Breakdown of the Insulation
The insulation on electrical conductors and cables needs protection so as to not create a shock or fire hazard in the future. With the right protection from the elements, electrical distribution systems can last for decades without deterioration or issues.
According to Appendix B of the CEC, the wires and cables should be marked with "SR", "SUN RES", "SUNLIGHT RESISTANT" or "CMX-OUTDOOR" (for communication cables).
In addition, Table 11 documents all of the types of outdoor cords that can be used for Christmas trees, portable equipment and stage lighting that are rated for WET conditions which also has been found to meet the CEC 2-134 sunlight exposure rule.
Note that thick, flexible cords rated for WET conditions can be used in all types of environments but flexible cords rated for DAMP or DRY outdoor conditions can not. Sizing conductors is still done according to CEC Section 4 (and Tables 1-4 along with Table 39) but the proper insulation material shall be selected for the operating environment.
Using the Right Outdoor Conductors
Because electricity is used above, below and all around users, it's important to use the wires with the correct insulation to maintain long-term safety. This may include XHHW-2, USE-2, RHH/RHH-2 electrical wire which are all sunlight resistant conductors.
As electrical consultants, we work with electricians to ensure that the correct conductors are used for each specific application. Sometimes that involves wires that is more resistant to oil and petroleum while the outdoor wires require to be sunlight resistant.