This policy extends to indemnify the insured against loss or destruction of or damage to any part or parts of the electrical machines, switchboards, installations or apparatus, forming part of the property insured (excluding rectifiers, radios, televisions or amplifying equipment of any description and electric motors in excess of 10HP) caused by the actual burning out of such part or parts by the electric current therein; provided always that the insurers shall not be liable for :
1. loss of use, depreciation, wear and tear;
2. loss or destruction of or damage to
A. lighting or heating elements, fuses or protective devices
B. electrical contacts at which sparking or arcing occurs in ordinary working.