(a) Whenever alterations, repairs, or additions are made to existing electrical installations the provisions of this chapter and the OBBC, where applicable, shall apply to all new work; provided, however, that where the provisions of OBBC and this chapter require the use of materials or methods of installation which differ from that in an existing building or other structure, and where the existing installation is in a safe condition, the Board of Building Standards and Building Appeals or the Ohio Board of Building Standards may approve the use of materials and installations corresponding to that existing within the building when it determines that the use of materials and methods of installation conforming to the provisions of OBBC or this chapter will not add materially to the safety of the installation, and that the installation as proposed will be adequately safe for the use and occupancy.
(b) The provisions of OBBC or this chapter shall not be interpreted to require alterations, replacements, or additions to electrical work or equipment installed prior to July 1, 1979 except where inspection and investigation by the Commissioner reveal the presence of a definite and serious hazard.
(c) The Commissioner shall determine that a definite and serious hazard exists only where the continued use of the electrical installation or equipment in question is, under customary or intended conditions of operation, demonstrably fire-hazardous, or demonstrably likely to cause injury or death from electrical shock.