Automatic Transfer Switch in Tharaka Nithi

Tharaka Nithi penalises a set twice over. Elevation of 722 m costs about 4.2%, and a design ambient of 34.5 °C costs about another 3.8% — a combination that is easy to underestimate because each factor alone looks tolerable. Sized on the datasheet rating, a set here runs closer to its limit on every load step, for its whole service life. That shows up as heat, as soot and as shortened time between overhauls rather than as an obvious failure on day one.

Hot-day margin. With 2025 reaching 36.4 °C at Kathwana, the worst day matters more than the average one — and it is the worst day that equipment is judged on. Whatever is installed here, the room it sits in decides whether it holds its rating: plant that is correctly sized but poorly ventilated protects itself by backing off, regardless of what the rating plate says.

Below 1,000 m. Elevation costs you only about 4.2% here, which is usually inside the margin a sensible specification already carries. The practical consequence is that altitude should not be allowed to dominate the discussion — at 722 m the air is still dense, and it is temperature and air cleanliness that will decide how this set ages.

Hot, but manageable. A design ambient between 31 and 36 °C is demanding without being exotic: standard equipment will usually cope, provided the installation does not fight it. Most of the trouble we are called to at this temperature is not the machine — it is the space around it. Recirculated hot discharge air, an undersized louvre, or plant boxed into a corner will defeat a correctly specified installation on the days it matters most.

Load profile. Tharaka Nithi is a smaller county, and the realistic constraint is usually parts and attendance rather than capacity. Standardising on a well-supported engine family matters more here than squeezing the last percent out of a sizing calculation — a set you can get filters and a fuel pump for is worth more than a marginally better one you cannot.

Getting there. Kathwana lies about 151 km north-east of our Embakasi, Nairobi workshop in a straight line — road distance is longer. Our mobile workshop covers all 47 counties, so visits here are planned rather than improvised — we confirm the fault description in advance so the right parts travel with the engineer.

How to read these figures. Altitude and temperature are for Kathwana, the Tharaka Nithi County headquarters — counties span wide ranges, so these are county reference points, not your site values. Derate percentages are planning indications of the order used across the industry (about 1% per 100 m above 300 m, about 2% per 5 °C above 25 °C); the governing figure is always the specific engine's derate table, which varies with aspiration and charge-air cooling. We size against that table and your measured site conditions, not against this page. Elevation: GeoNames, via the Open-Meteo Geocoding API. Temperature: Open-Meteo ERA5 reanalysis, 2025 daily maxima. Both CC BY 4.0, retrieved 2026-08-08.