Choosing the right capacity.
WHAT TO START FROM
Your essential load list.
WHAT TO ADD
Starting surge for motors and compressors.
HOW MUCH
Several times running wattage for those items, briefly.
WHAT TO ADD AFTERWARDS
Headroom, for equipment you may add.
HOW MUCH HEADROOM
Modest. Around a quarter.
WHY NOT MORE
Oversizing costs money, fuel and engine life.
WHAT UNDERSIZING PRODUCES
Tripping, overheating, and early failure.
WHAT OVERSIZING PRODUCES
Higher purchase price Poor efficiency at light load Deposits and damage in diesel engines
WHY THAT SECOND POINT SURPRISES PEOPLE
A generator running at a small fraction of its rating is being harmed.
WHAT TO DO IF YOUR LOAD VARIES ENORMOUSLY
Consider two smaller units rather than one large one.
WHAT THAT PROVIDES
Efficiency at low load, capacity when needed, and redundancy.
WHAT TO CHECK BEFORE BUYING
That the rating is continuous, not peak That the fuel consumption figure is stated That parts and service are available locally
WHY LOCAL PARTS MATTER MOST
A generator that cannot be serviced is scrap.
WHAT TO ASK THE SUPPLIER
Consumption at half and full load Service interval Warranty terms Where parts come from
WHAT TO AVOID
Buying on price alone Ratings that seem implausible for the price
