NEC3 PSC Option A Proposed Instructions

Under clause 61.2 can a Consultant change an Employers instruction and submit a quotation?

No the Consultant does not have the right to do this. They are required to submit a quotation for the proposed instruction. If the Consultant is struggling to prepare a quotation because the proposed instruction was not clear then they should ask the Employer to clarify the proposed instruction and re-issue it or alternatively they could ask the Employer to state assumptions about the compensation event under clause 61.6.