NEC ECS: Accepting Subcontractor's Design

Subcontractor’s design has been accepted for manufacture but upon installation this has highlighted errors in their design. Under clause 14.1, is design liability for rectifying this error the subcontractor’s despite the design being accepted?

Yes - it is still Subcontractor liability if elements did not comply with the original Works Information even if the Contractor had accepted the design.

Acceptance is more about seeing if there is a reason to reject, rather than having to go through the submission with a fine tooth comb to see if there are any accidental/deliberate errors in that submission that the Contractor would then be liable for.