Many times the tower owner or management firm's project manager will be responsible to coordinate with the power and telco provider to identify where the service demark points are located on a greenfield site. To expedite a drawing package, he will sometimes provide the architect with information based upon a visual observation. He still has not met with the service planner at the time of the site visit and tells all potential bidders that the electrical and/or telco scope of work may change. Seldom will you see an addendum prior to the bid opening. Bid competitively based upon the drawings, but include adders and deducts in your proposal for the possible changes to avoid a conflict once the contract is let.