A three phase generator supplies 400 V across three live conductors, the same as a three phase municipal or Eskom connection, so it can run motors, compressors, welders, borehole pumps and machinery that a single phase unit cannot start. Most are diesel, from about 10 kVA up to several hundred kVA. GeneratorRepair.co.za is a free quote service: you describe your site and loads on one form, and we pass it to independent generator dealers and installers, who quote you directly. Tell them what you run, and they size the generator 3 phase or not.
Do you need a three phase generator?
Check your supply first. If your DB board has a three-pole main breaker and a three phase meter, and you run any three phase motors, you need a three phase generator to back it up. Typical users are:
- Workshops and factories: lathes, compressors, CNC machines and welders
- Farms: borehole and irrigation pumps, milking parlours, cold rooms and poultry fans
- Business premises: lifts, large air conditioning and commercial kitchens
A large house on a three phase supply with no three phase motors can sometimes use a single phase unit on essential circuits only, which is cheaper. Ask the dealer to compare both.
Sizing: kVA, kW, motor starting and balanced loads
Generators are rated in kVA, while loads are listed in kW. At the usual 0.8 power factor, a 100 kVA generator gives about 80 kW. Electric motors draw three to six times their running current when they start, so a 15 kW pump may need a 40 kVA set unless it has a soft starter or variable speed drive.
Single phase loads should be spread evenly across the three phases. Badly balanced loads overheat one winding and upset the voltage regulator, a common cause of alternator repairs. On the Highveld, allow for altitude derating of roughly 3 to 4% per 300 m above 1,000 m, plus extra margin for summer heat.
Three phase diesel generator for sale: what you get
Most three phase diesel generators come as a canopied set with a water-cooled engine, a brushless alternator with an AVR, a digital controller and a base fuel tank of 8 to 24 hours. For standby use, pair it with an automatic transfer switch so it starts during load-shedding. A silent canopy matters in towns, and a sealed, dust-filtered canopy matters on farms and mines.
Installation and compliance
A fixed three phase generator must be connected by a registered electrician, with correct earthing, neutral switching and a Certificate of Compliance under SANS 10142-1. Never run it in a closed room or garage. Ask for the plinth, cabling and changeover on the same generator installation quote so the totals are comparable.
What to include in your request
- List your three phase motors and their kW ratings
- Say whether it is standby or prime (continuous) power
- Give your main breaker size and supply type
- Mention the site altitude, dust or coastal exposure
- Ask for installation, ATS and CoC on the same quote
Three Phase Generators for different sites
- Homes: a large house on a three phase supply with a pool pump, borehole and heat pumps
- Estates and complexes: a body corporate set running the gate, booster pumps, lifts and common lighting
- Farms and smallholdings: a diesel set behind the borehole, irrigation pumps, dairy and cold room
- Shops, offices and restaurants: a canopied genset backing up air conditioning, lifts and a commercial kitchen
- Factories, mines and sites: prime or standby power for compressors, welders, conveyors and production lines
- Lodges, venues and events: a silent three phase set keeping a lodge kitchen, laundry and pumps running
- Clinics, schools and towers: standby power for a clinic, school, water pump station or cell tower
Frequently asked questions
Does GeneratorRepair.co.za sell three phase generators?
How much does a 3 phase generator for sale cost?
Can a three phase generator supply single phase plugs?
Can I buy a used three phase generator instead?
Three Phase Generators by province and city
- Johannesburg
- Pretoria
- Centurion
- Midrand
- Sandton
- Randburg
- Roodepoort
- Krugersdorp
- Randfontein
- Germiston
- Boksburg
- Benoni
- Kempton Park
- Alberton
- Vanderbijlpark
- Vereeniging
- eMalahleni (Witbank)
- Middelburg
- Secunda
- Mbombela (Nelspruit)
- Rustenburg
- Brits
- Klerksdorp
- Potchefstroom
- Mahikeng
- Polokwane
- Tzaneen
- Kimberley
- Upington
- Bloemfontein
- Welkom
- Sasolburg
- Durban
- Pinetown
- Pietermaritzburg
- Richards Bay
- Newcastle
- Ladysmith
- Gqeberha (Port Elizabeth)
- East London
- Kariega (Uitenhage)
- Mthatha
- Cape Town
- Bellville
- Paarl
- Stellenbosch
- George
- Worcester