Marcus flipped the breaker. A low hum filled the room as the transformers energized.

is the International Electrotechnical Commission’s standard for Low-Voltage Electrical Installations (up to 1000V AC or 1500V DC). It covers safety, design, erection, and verification of electrical systems in buildings.

Elias walked over to the panel, using a voltage tester. Even though the main power was still on (thanks to Marcus's stubborn refusal to use RCDs), the casing was live.