Trump has blocked foreign-made transformers and other critical grid gear from the US electricity network, a hit to Chinese suppliers and a new headache for utilities already waiting years for parts.

• The order bans buying, importing, or installing certain foreign-made grid equipment and its software, citing hacking risks.
• China is the main target — it makes most of the world's batteries and solar inverters, and sent large numbers of big power transformers to the US over the past decade.
• Utilities have already been told the affected gear is off limits while the Energy Department writes the rules, with 120 days to publish them.
• Grid equipment is already in short supply, so the ban will likely stretch out delivery waits even further.
• Recent hacks on US water systems pushed both parties toward treating grid parts as a security problem.

Outlook: Expect longer waits and higher costs for grid equipment as the Energy Department turns the order into binding rules over the next few months.