The generator

Electricity kills at surprisingly low voltages, especially with wet hands. A current of a few tens of milliamps across the chest can stop the heart, and around 50 V AC is where shock becomes dangerous in wet conditions.

Before anything is energised:

• Earth every exposed metal part to a buried earth electrode.
• Fuse every circuit, sized below what its wire can carry, so the fuse fails before the wire burns.
• Lock off and prove dead: before work, isolate the supply, lock it, and test the circuit is dead with a tester proven on a live source.
• No work on live circuits. Nobody works alone on electrical plant.

This is the real bottleneck of the tier, not the concept. Draw wire as for the telegraph, from the purest copper you can get — impurities sharply raise resistance, so electrolytic refining pays for itself.

Insulate it with varnished cotton or silk, or enamel. The insulation must survive heat and vibration for years: test a coil by heating it well above its working temperature for a day and checking for cracks and softening. Record wire diameter: halving the diameter quadruples the resistance.

Coils rotating in a magnetic field, with a commutator that takes off direct current. Start with permanent magnets, then move to a self-exciting field winding, which is the trick that makes large machines practical.

Laminate the iron core: solid iron heats up from induced eddy currents and wastes a large share of the power. Stack thin iron sheets — around 0.35–0.5 mm — each insulated with varnish or paper. Build small first: a machine of a few hundred watts that runs reliably teaches more than a large one that burns out.

A generator run backwards is a motor; the same machine does both. Feed current into the dynamo and it turns.

This is what puts power at every workbench instead of at the end of a line shaft — one engine and generator, wires to the shop, and a small motor on each machine. Fit each motor with its own switch and fuse, and a guard on its pulley or coupling.

Alternating current can be transformed to high voltage for transmission and back down for use, and transmission loss rises with the square of the current — double the voltage, quarter the loss for the same power. This is the entire reason grids are AC.

Frequency = number of magnetic poles × revolutions per minute ÷ 120. A four-pole alternator at 1,500 rev/min gives 50 Hz. Pick one frequency — 50 or 60 Hz — for the whole settlement and never change it, and govern the engine's speed to hold it. Three-phase is better still: it gives self-starting motors and more power per kilogram of copper.

A transformer is two coils on a shared laminated iron core. The voltage ratio equals the turns ratio: 10 turns on the secondary for every 100 on the primary steps voltage down tenfold.

Transmit at higher voltage over distance and step down near the user to a safe working voltage. Higher voltage lines need more insulation, greater clearance from people and ground, and warning signs. Keep every transformer earthed and fenced.

1. Workshop motors — the largest productivity gain.
2. Lighting — extends the working day and transforms study and craft.
3. Pumping and water treatment — including chlorine production.
4. Heat and electrochemistry.

Meter each circuit so the settlement knows where its power goes, and size the generation to the load plus a margin — an overloaded generator overheats, its voltage sags, and motors on it burn out.