Common trade practice regarding conduit has been that 'laborers' are allowed to install it. Duct banks for data/comm around here, are all 'laborer' installs. As far as I am aware, our POCO uses 'laborers' also. Keep in mind that these 'laborers' are union.
The cable/wire is 'sparkies' or CWA guys.
An old tale around here is 'once upon a time, the electricians were 'to busy' to want the UG pipe work'. Lately, the 'story' ahs changed, due to guys being 'not busy'; but it's too late.
