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Generator selection: petrol or diesel

How to choose a generator for a home: petrol or diesel, single- or three-phase, power calculation, auto start (ATS), connection via transfer switch.

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Generator types

TypePowerLifeNoiseApplication
Petrol0.8–15 kW1000–3000 h65–75 dBOccasional backup
Diesel2–2000 kW10000–40000 h70–90 dBContinuous backup, industry
Gas3–100 kW20000+ h55–65 dBHomes with gas line
Inverter0.8–6 kWlike petrol50–60 dBElectronics, clean sine

Power calculation

1. Sum the power of simultaneously working appliances. 2. Add inrush currents: 3–5× for motors (pumps, fridges). 3. Add 20–30% reserve: P = ΣP × 1.3.

Rule: run the generator at 30–80% load. Constant light load causes carbon deposits; full load shortens engine life.

Single-phase or three-phase?

For a single-phase intake — a single-phase generator only. A three-phase generator with single-phase loads overloads one phase (max 1/3 of rating per phase).

Connection: ATS and transfer switch

Never plug a generator into a wall socket — backfeed can kill utility workers. Connect via a transfer switch or ATS (automatic transfer switch with auto start).

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Data is for reference. Final design decisions must follow current regulations and a qualified engineer.