Heavier loads
Heaters, geysers and blowers switch on together in winter, and a transformer sized for summer can find itself overloaded every evening. If lights dim or breakers trip at the same hour each day, measure the load — it may be time for a larger rating or for spreading loads across phases.
Low voltage often comes with it, at the end of long lines under heavy load. Motors on low voltage draw more current and run hotter, which is a common cause of winter burn-outs.
Moisture in idle equipment
A motor or transformer that sits unused through a cold, damp spell can take in moisture, and damp windings lose insulation resistance. Starting it straight up can cause a fault.
- Before restarting idle equipment, have its insulation resistance checked with a megger.
- If it reads low, dry the windings out gently before running on full load.
- Store spare motors somewhere dry, off the floor, and covered.
Oil-type transformers in the cold
Cold oil is thicker, so it circulates less freely when a transformer first takes load. A breather filled with silica gel lets the tank breathe while keeping moisture out; the gel changes colour — commonly from blue or orange to pink or green — as it becomes saturated, and then needs replacing or reactivating.
- Check the breather colour through the season.
- Check the oil level and look for leaks at gaskets.
- Keep radiator fins clear of packed snow so heat can still escape.
Ventilation and snow
Covering a motor or transformer to protect it from snow can starve it of air. Protect it from direct snow and water, but leave the vents and fan intake open. Clear snow drifts away from outdoor units after heavy falls.
General guidance only — every installation is different. For work on live equipment, use a licensed electrician. Last reviewed 28 September 2026.