I've found that my dupes don't build 20 kW wires made with pure metal and they need an "Electrical Engineer" job in order to start building. Nothing said about it neither in a job description nor in wires description.
Steps to Reproduce
Order to build a 20 kW wires from iron. Dupes will bring iron but won't start building until got an "Electrical Engineer" or already mastered in it.
This issue has not been confirmed by a developer yet.