58Sub-contractors
For the purposes of this Chapter a party to a contract relating to construction operations is a sub-contractor if, under the contract—
(a)he is under a duty to the contractor to carry out the operations, or to furnish his own labour (in the case of a company, the labour of employees or officers of the company) or the labour of others in the carrying out of the operations or to arrange for the labour of others to be furnished in the carrying out of the operations; or
(b)he is answerable to the contractor for the carrying out of the operations by others, whether under a contract or under other arrangements made or to be made by him.