Great question. If all electrical work is contracted out, the host employer ( your company in this case) is still responsible to make sure that the contractor is following applicable codes and safety standards, up to and including your local electrical safety program. Contractor/host employer relationships are critical in ensuring that electrical employees perform work in a manner that is safe for all involved.
One important thing to consider is the need of the contractor to have a written electrical safety program that meets or exceeds the host company's program. This program should incorporate the safety principles involved in NFPA 70E (2015) and at a minimum, comply with OSHA electrical regulations. If this approach is taken, both the contracting group employees and the host employees are by default reducing the risks of exposure to electrical shock, arc flash, arc blast, and other associated injuries from electrical incidents.
The old idea of contracting out the electrical work and looking the other way is no longer an option in today's safety culture. We are all responsible for workplace safety.
We have spoken to many EHS managers who believe that once "electrical work" is contracted out, so are the employers responsibilities. This is not true. In fact, most employer / electrical contractor relationships are either covered in the NFPA 70E or OSHA 1910.269. From recent audits we have performed, it was found that employers did not request: proof of 70E training from contractors; proof of the contractors electrical safety program; and the contractors use of protective clothing and equipment for shock and arc flash was non-existent. Employers may believe that since they are not the "experts" they can "contract it out", the fact remains that OSHA and NFPA 70E make the host's responsibilities to the contractor very clear. We would recommend that you perform regular audits on your contractor. Refer to section 110.3 in the NFPA 70E - 2015 and OSHA 1910.269 (a)(3). It may also be a good idea to get non-electrical EHS managers trained on basic electrical safety requirements, although this is not required by law.