Nonconductive optical fiber cables are permitted to occupy the same tray or raceway with power conductors and Class 1 circuits. Running electrical and data cables in the same conduit might seem like a tidy, cost-effective idea but it often leads to signal interference, compliance issues, and expensive headaches down the line. Electrical cables can produce electromagnetic interference (EMI), which can degrade data. General Consideration: It is generally not recommended to run fiber optic cables in the same conduit as electrical power cables. This is due to several potential risks and complications that can arise from such an arrangement. :-? and. Mastering NEC guidelines with a thorough understanding of Art. Note that two exceptions exist. You can use unlisted outside plant optical fiber cables, and you can install them in building spaces. But they can't go in risers, environmental air ducts, environmental.