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Generator School · 11

Common installation pitfalls — and how to avoid them

Every site we attend for an emergency call-out, we're looking for the same handful of installation faults. They're well-known to anyone who's done this work for a decade, and they're all easy to design out — but only if the installer knows what to look for.

01

1. Under-sized fuel pipework

If the fuel line from the bulk tank to the day tank can't deliver fuel as fast as the engine burns it, the engine will run, fault on fuel-pressure, and shut down — typically 15 minutes into the first real outage. We calculate fuel demand at 100 % load PLUS day-tank refill rate for every install.
02

2. Inadequate ventilation

A diesel generator at full load dumps roughly the same heat as it produces in electricity. A 100 kW genset throws 100 kW of waste heat. The plant-room intake and exhaust louvres have to be sized for the full airflow plus de-rating for ambient temperature. Get this wrong and the unit thermal-trips before reaching full output.
03

3. Battery reverse polarity

Two cables, two terminals — getting them swapped instantly fries the engine ECU, the controller, and (sometimes) the charging alternator. Always fit anti-reverse battery posts and label everything. Cost of being wrong: $3,000–6,000 of replacement electronics.
04

4. No load-shed strategy

If the generator is sized for 80 % of the building's worst-case load (very common in value-engineered projects), there has to be a load-shedding contactor that drops non-essential loads on generator mode. Without it, the genset overloads and trips off — leaving the whole building dark.
05

5. Missing earth bond

A 'floating' alternator without a proper earth bond to the building's MEN system creates dangerous touch voltages on every metal surface in the building when the generator is running. AS/NZS 3010 mandates how the bond is done and tested. Test resistance to true earth at commissioning AND at every annual service.
Quick answers

FAQs

Don't see your question? Call 07 5529 0351 or contact us.

Ventilation airflow and fuel-line size — yes, with measurements. Battery polarity and earth bond — only with proper test equipment. If in doubt, book a single-day site audit (~$650 + travel).

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