I lease a building to assemble and ship. I have no one working
on electrical equipment. I use contractors for all electrical work.
Who is responsible for completing an NFPA 70E analysis and
labeling everything me or the building owner?
Although you leased the building, the decider is who installed the electrical equipment? If the landlord installed those, it will belong to the landlord who shall then be responsible to pay for the study. If the landlord owns the "shell" but you installed the equipment, then it will be your liability. The contractor can pay for the study, but will then add cost and transfer to you - makes sense for you to pay for the study in that case.