If your company handles EPC projects, what kind of projects are these? Where are they handled, and which industry, in general, is your customer?
The Role of an HR Manager
The position of HR Manager has a distinctive functional identity. Why do you think this position should have technical knowledge? If technical knowledge is that important, why not shift the existing technical manager laterally and have them work in HR?
What is your designation, and in what department do you work? Was your selection based on technical knowledge? Whether you work in a technical department or not, why are you not able to develop technical questions?
Technical knowledge is required for an HR Manager, but it is a secondary requirement, not a primary one. Therefore, when selecting a person for this position, concentrate on whether they have handled recruitment for a similar business. The second factor to consider would be your organization's cultural issues. What are the cultural issues hindering your organization's growth? You should be able to judge if that candidate is capable of solving those issues.
To a certain extent, this issue can be solved through "Behavioral Interviewing." If you wish to master this technique, feel free to approach me.
Thanks,
Dinesh Divekar