Short answer
Choose the generator by its continuous power, not its peak: add up what you'll connect at once, add the start-up peak of the largest motor and leave 20–30% headroom. Then confirm voltage, phases and frequency—60 Hz in Central America—and pick gasoline or diesel by daily hours of use.
Work out the kVA from your loads1. Continuous power, not peak
Datasheets show two numbers. Peak (or «standby») power is what the generator gives briefly, for example to start a motor. Continuous power is what it sustains for hours. Size on continuous power and run at around 70–80% of it: the engine lasts longer and doesn't trip on a peak.
Catalog example, according to Wacker Neuson's datasheet: the GP7000A gives 7,000 W peak and 6,800 W continuous. For a steady 6,500 W load it's too tight; the next size up, the GPS9700A with 9,000 W continuous, is the better choice.
- G3500G: 3,000 W
- GDS5500G (diesel): 5,500 W
- GS6503G (three-phase): 6,000 W
- GP7000A: 6,800 W
- GPS9700A: 9,000 W
- GS10003G (three-phase): 9,000 W
- Source: Wacker Neuson datasheets in the catalog.
2. Work out your load, including motor starting
List what will run at the same time and note each unit's power; it's on its plate. Separate the ones with motors—mixers, pumps, compressors, saws—: at start-up they draw several times their running power for a few seconds. As a rule of thumb, count 2 to 3 times, and more for compressors and pumps that start under load; the exact figure is in the equipment manual.
Example: three 400 W floodlights, a 1,500 W grinder and a 1,000 W mixer that draws about 3,000 W when starting. Running, they add up to 3,700 W; at the mixer's start, 5,700 W. A generator with 6,800 W continuous covers both numbers with headroom. If you start motors one by one, with everything else off, the peak drops.
- Add running power: Everything running at once
- Add the start-up: Largest motor × 2–3
- Add headroom: 20–30% over continuous
- Check the plate: Voltage, phases and 60 Hz
- Adjust for altitude: Manufacturer's table
3. Voltage, phases and 60 Hz: check the frequency
In Central America the grid runs at 60 Hz. Tools and light site equipment usually take 120 V or 120/240 V single-phase; large motors and some site panels need three-phase. Before buying, check three datasheet values: output voltage, number of phases and frequency.
Not every generator on the market is 60 Hz. In the catalog, for example, the Wacker Neuson GS6503G and GS10003G are three-phase 230/400 V at 50 Hz according to their datasheet: they're designed for 50 Hz grids. At 50 Hz, motors built for 60 Hz run slower and overheat. By contrast, the GDS5500G datasheet states 120 V at 60 Hz, and the G3500G has a 120 V, 60 Hz version. If the datasheet doesn't state the frequency, ask for it in writing in the quote.
4. Gasoline or diesel, and how many hours
Gasoline generators are light and portable; they work well at low power and intermittent use. Diesel units cost more up front, but burn less per kWh and handle continuous shifts better: they're the choice for several hours a day or for a camp. If your site already runs on diesel, a diesel unit takes gasoline out of the inventory.
Work out runtime from the tank and fuel use at your real load. According to Wacker Neuson's datasheets, the G3500G runs 11 to 14 hours at 50% load on 18 liters, and the GDS5500G 11 hours at 50% on 14.5 liters. That defines how many times a day someone refuels.
| Criterion | Gasoline | Diesel |
|---|---|---|
| Weight | Lighter | Heavier |
| Upfront cost | Lower | Higher |
| Fuel per kWh | Higher | Lower |
| Ideal use | Intermittent, low power | Long daily shifts |
| Example | G3500G, GP7000A | GDS5500G |
5. Altitude and heat reduce power
A combustion engine breathes less air at altitude and in heat, and delivers less power than the plate rating. On the coast it's barely noticeable; in Guatemala City or Quetzaltenango, it is. Every manufacturer publishes a derating table for altitude and temperature: apply it before choosing the size, especially if you'll run close to the limit.
6. Safe connection
Three non-negotiable rules. Ground the generator as its manual instructs. Never connect it to a building's wiring without a transfer switch: current can back-feed into the grid and electrocute line workers. And never run it indoors: carbon monoxide can't be seen or smelled. Place it outdoors, away from doors and windows.
Maintenance goes by operating hours, per the manual: oil, air and fuel filters, and spark plugs or injectors. On dusty sites, check the air filter more often.
7. If it's for night lighting: a light tower
When the generator is for lighting a work front at night, a light tower with its own engine often beats a generator plus loose floodlights. SIMAQ, the group's own brand, has towers in all four countries: according to its datasheet, the SQTLK 6000 runs at 60 Hz with a 9 m mast, and the NIGHTMASTER LED 350 carries 4 × 350 W LED floodlights on a 7 m mast that rotates 350°. The site's light-tower calculator helps you estimate how many you need.
Where to buy a site generator in Central America
Grupo ConstruMarket offers Wacker Neuson generators in El Salvador and Guatemala, and SIMAQ light towers in all four countries. In El Salvador and Panama, the Bobcat line also includes Portable Power (Doosan) power generation: ask about available models. In Nicaragua and Panama, check with an advisor which generation option fits your site.
Price depends on power, fuel, phases and frequency. Tell us what you'll connect and an advisor will contact you during business hours with the recommended size. Light equipment can be paid in installments with participating credit cards.
- El Salvador: Zaragoza, Antiguo Cuscatlán and San Miguel.
- Guatemala (CMARKET): Mixco, Río Hondo and Xela.
- Nicaragua: Managua. Panama: Panama City.
Summary: what to choose
| If… | Then… |
|---|---|
| Power tools and lighting for a small crew | ~3 kW continuous (G3500G type) |
| Several tools at once plus a mixer | 6–7 kW continuous (GP7000A type) |
| Many hours a day or a camp | Diesel (GDS5500G type) |
| Three-phase motors | Three-phase generator matching your equipment's frequency |
| The datasheet says 50 Hz | Not for 60 Hz grid equipment |
| You only need night lighting | SIMAQ light tower |
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Topic: Electric generator
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Common mistakes
Buying by peak power
Peak lasts seconds; the one that works for hours is continuous.
Forgetting motor start-up
The mixer or pump can draw 2–3 times its power at start-up and trip the generator.
Not checking the frequency
A 50 Hz generator overheats motors built for 60 Hz.
Connecting it without a transfer switch
Current can back-feed into the grid and electrocute a line worker.
Running it indoors
Carbon monoxide kills without warning.
Frequently asked questions
What size generator do I need for a jobsite?
Add the power of what runs at once, add the largest motor's start-up peak (2–3 times its power) and pick a generator whose continuous power sits above that with 20–30% headroom. An advisor can run the numbers with you from your equipment plates.
How do I convert kVA to kW?
Multiply kVA by the power factor. For site generators 0.8 is normally used: a 10 kVA generator delivers about 8 kW. If the datasheet already gives continuous kW, use that number.
Can I use a 50 Hz generator in Central America?
Not for equipment built for the 60 Hz grid: motors run slower and overheat. Check the frequency on the datasheet and ask for the model's 60 Hz version.
Gasoline or diesel generator?
Gasoline for intermittent use and low power: it's lighter and cheaper to buy. Diesel for long shifts every day: it burns less per kWh and handles continuous work better.
Where can I buy a generator in Guatemala?
At CMARKET, part of Grupo ConstruMarket, which offers Wacker Neuson generators from Mixco, Río Hondo and Xela. Price depends on power, fuel and frequency; the quote is tailored.
How often does a generator need maintenance?
By operating hours, per the manufacturer's manual: oil change, air and fuel filters, and spark plugs or injectors. On dusty sites, check the air filter more often.
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