Motor Rewinding in Mombasa

Heat, not height, is the constraint in Mombasa. At 20 m elevation costs you only about 0%, but a design ambient of 32.3 °C — with 2025 peaking at 34.6 °C — costs roughly 2.9%. Hot air is both thinner and worse at carrying heat away, so the same machine is making less power while working harder to cool itself. That makes radiator sizing, enclosure ventilation and free air space around the set the decisions that actually determine whether it holds rated output in the afternoon, when your load is usually highest.

Marine air. On the low-lying coastal strip of Mombasa, salt-laden air attacks a generator continuously whether or not it is running. Standard enclosures corrode from the inside out, alternator windings and control-panel terminations suffer first, and the damage is usually well advanced before it becomes visible. Marine-grade or upgraded enclosure treatment, sealed terminations and a shortened inspection interval are not optional extras at this exposure.

At sea level. Barometric pressure here is what the rating plate assumes, so you get the full published output — the only place in the sizing conversation where nothing is taken away. Spend the attention you would have spent on altitude on the foundation, the exhaust route and the ventilation path instead; those are what limit installations at 20 m.

Hot, but manageable. A design ambient between 31 and 36 °C is hard on a set without being exotic: standard cooling packages will usually cope, provided the installation does not fight them. Most of the trouble we are called to at this temperature is not the generator — it is the room. Recirculated hot discharge air, an undersized louvre, or a set boxed into a corner will take a correctly specified machine and derate it anyway.

What this does to windings. Insulation life is governed by temperature: the accepted rule is that every 10 °C of sustained overtemperature halves it. A motor at Mombasa starts from a 32.3 °C ambient before it generates any heat of its own, so the insulation class and the cooling arrangement decide how long a rewind lasts far more than the winding wire does. Specifying a higher class than the minimum is usually the cheapest life extension available at this ambient.

Load profile. With over a million residents, Mombasa carries a real mix — commercial premises, institutions and light industry — and the sets we are asked about here are usually replacements rather than first installations. That changes the question: the existing cable, transfer switch and foundation usually constrain the answer more than the load calculation does, and surveying what is already there is worth more than a catalogue.

Getting there. Mombasa lies about 432 km south-east of our Embakasi, Nairobi workshop in a straight line — road distance is longer. Our mobile workshop covers all 47 counties, so work this far out is planned around parts availability: we carry the consumables and wear items for the visit rather than making a second trip for a filter.

How to read these figures. Altitude and temperature are for Mombasa, the Mombasa 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.