Build 42 Generators — All Four Variants, Fuel Math, and Placement Rules

When the grid dies, your base runs on whatever generator you hauled home — and Build 42 turned generators into a real decision, with four variants that differ in noise, weight, and reliability, plus a fluid system that changes how fuel itself behaves. This guide covers every verified number on stable 42.20, from PZwiki's Generator page (stamped 42.13.1) and the B42 fluid changes. Checked 2026-08-04. For the broader pre-shutoff plan, see our water and power shutoff guide.

The four generator variants

The trade-off is simple: Premium Technologies is the quietest and most durable; the Old generator is the loudest; ValuTech is the only one you can carry with less encumbrance but degrades fastest and carries its noise farther than the premium units. Each variant also has a different chance of durability loss per use, with ValuTech highest.

Two repair facts apply to all four: generators are fixed with 1 × scrap electronics, restoring 4% + 0.5% per Electrical level — and if condition drops to 20% or below, the generator can catch fire or explode. Don't run a scuffed unit unattended.

Where to find them: warehouses, garages, tool sheds, and self-storage facilities. Guaranteed spawns include the military blockade near Louisville, the Echo Creek festival zone, and the Doe Valley Secret Bunker — room definitions shed, garagestorage, and storageunit can also auto-spawn them.

Power radius: the 20-tile cylinder

Every generator powers devices in a cylinder of radius 20 tiles, extending 3 floors up and 3 floors down (total height 7 levels, base diameter 41 tiles). Placement logic follows:

• One basement generator can power the whole house above it.
• A ground-floor unit reaches the attic and the basement — you rarely need two generators for a single home.
• Position the cylinder to also cover your workshop sheds and rain collector pumps if you have them.

Connect it to the house wiring via the "Connect Generator" context menu. That action requires Electrical 3, the Electrician or Engineer occupation, or reading the How to Use Generators magazine — loot the magazine early if you didn't roll the skill.

Fuel math: liters per hour

Generators burn gasoline. Baseline consumption with zero load is 0.002 L/h, and every powered device in range adds load:

Runtime = fuel remaining ÷ total demand. Worked example from the wiki: a popsicle fridge (0.016), TV (0.003), six lamps (0.0012), plus base draw = 0.0222 L/h — a full 10 L generator runs about 450 in-game hours, roughly 18.7 days. Check any generator's live load with right-click → "Generator Info."

Practical takeaways: lights are nearly free, fridges dominate household load, and running a stove electrically is a fuel tax — fire pits and outdoor cooking cost nothing.

Fueling in the fluid system

The tank holds up to one gas can (10 L) and can only be filled while the generator is off — right-click → "Add Fuel". B42's fluid rules shape the rest:

• Siphoning vehicles and pumps needs a hose — add one to your generator kit, or you'll be pouring from cans only.
• Jerry cans hold 20 L each; stockpile them before the pumps die.
• Gasoline evaporates from open containers — keep fuel in sealed cans, not buckets or pots.
• You can't siphon fuel back out of a generator, but fuel stays inside when you pick the unit up and move it.

With the Generator Working In Exterior sandbox option enabled, you can also hook generators to world buildings — the classic play is powering a gas station's pumps to keep tapping its underground reserves.

Placement discipline

Three rules prevent stupid deaths:

1. Never run a generator indoors — exhaust drops character health fast, down to 1, and the building stays unsafe until the unit is switched off.
2. Respect the noise radius. Zombies hear it (20–25 tiles by variant). Put it behind walls at the edge of your perimeter, not at the front door — and remember exterior noise stacks with hordes in ways combat pacing can't always absorb.
3. Carry, don't fight. Generators are carried, not inventoried: while carrying one you can't attack, moving triggers the heavy-load moodle, and equipping a weapon drops the generator on your tile. Move them in a cleared lane, ideally by vehicle.

Verified on 42.20 · Last checked 2026-08-04

Variant stats, radius, consumption table, repair formula, and spawn locations come from PZwiki's Generator page (stamped 42.13.1); fluid-system fueling rules (hose siphoning, 20 L jerry cans, evaporation) from the Build 42 change set, community-reported where the wiki has not re-stamped exact values. Exact per-variant degradation probabilities are not published — treat "ValuTech degrades fastest" as the only confirmed ordering.