The US is pushing Chinese-made gear out of its power grid, and that is good news for Taiwan's four big heavy electrical companies.

• Washington now treats grid equipment as a national security issue, not just a purchase decision.
• Transformers, high-voltage switches and control systems were added to the defense-critical list in April, with tighter rules on foreign-made large power equipment in August.
• America cannot build enough of this gear itself — big transformers take years to make — so suppliers from Taiwan, Japan, Korea and Europe are being pulled in to fill the gap.
• Hua Eng, Shihlin Electric, Chung-Hsin Electric and Allis are each staking out a different slice: transformers, high-voltage switchgear, substations and power engineering.
• Old grids plus a boom in data centers mean demand keeps climbing, and cheap Chinese prices no longer win the order.

Outlook: Taiwanese suppliers that get certified and expand capacity fast should keep winning North American orders as the grid rebuild runs for years.