Every megawatt of data-centre load needs transformers, switchgear and high-voltage cable before it is worth anything. That equipment used to arrive in about a year. It now takes three to four, and the order book is full before the factory opens.
The supply is narrow and industrial: Hitachi Energy, Siemens Energy, Schneider Electric, Eaton, ABB and Korea's Hyosung and HD Hyundai Electric in large power transformers; Prysmian, Nexans and NKT in HVDC cable, which is why Italy — not Germany or the United States — leads the cables sub-layer on the ownership basis.
This is the least glamorous chokepoint in the atlas and possibly the most binding. A GPU order can be expedited. A 400 kV transformer cannot, and every grid connection, every renewable interconnector and every new substation is competing for the same slots. Switch the tier rail to Power & Grid and the sub-layer concentration bars make the shape of it obvious.