Can flexible cords be hung in tunnel shafts?

OSHA standard 29 CFR 1926.405(a)(2)(ii)(I) states “Flexible cords and cables shall be protected from damage.” Type “SO” flexible cords must be protected from physical damage when mounted on the inside of a tunnel shaft. The insulation on type “SO” flexible cords is not suitable protection against physical damage when the flexible cord is subject to being struck by heavy objects. The raising and lowering of the muck bucket through the shaft opening could create this condition. Type “SO” Flexible Cord should be located outside of the shaft, concealed behind “H” piles, or physically protected in another fashion to limit the possibility of damage to the cord’s insulation and subsequent energizing of other conductive material. Although “SO” flexible cords are suitable for hard and extra hard usage, these cords were not manufactured to withstand this type of abuse.

Regarding your concern about running type “SO” flexible cord with utilities in tunnel work, this is permitted under 29 CFR 1926.800(s)(1) if adequate mechanical protection is provided to assure the integrity of the cord’s insulation and in such a fashion that any inadvertent damage to the cord’s insulation will not result in energizing of other utility systems.