If the Generator Is on the Roof, Fit a Loadbank Connection Point — or You Will Be Draping Cables Through the Building
A weekly run with no load proves the engine turns. It does not prove the set will carry the building.
That is what a loadbank test is for. You put real kilowatts on the alternator so the engine, the cooling, the AVR and the exhaust all work as they will on the night the mains fails. Wet stacking, light-load glaze, a radiator that only just copes at tickover — none of that shows up until you ask the machine for current.
On a set in a yard, that is straightforward. Van, loadbank, tails onto a test point or the output breakers, run the test, pack up.
On a set on the roof, it is a different job — unless somebody thought about it when the plant was designed.
What happens when there is no connection point
The loadbank lives on the ground. The generator lives six, eight, twelve storeys up. The only way to join them is cable.
So you end up:
Running heavy test leads up the stair core or a riser that was never meant for it
Draping cables through the building — corridors, plant landings, past fire doors that will not close on a 185 mm tail
Going over ledges, parapets and roof edges with no proper support, so the cable hangs in the weather and in anyone’s way
Dropping down the face of the building because that is the only straight route, which looks like a circus to the neighbours and is a poor way to treat a test lead
Fighting access, permits, lifts that will not take a drum, and a facilities manager who quite reasonably does not want live test cables in a residential hallway
It can be done. We have done it. It is slower, dearer, messier and harder to repeat every year. It is also how a “simple loadbank” turns into a two-day production with cones on the pavement.
What a loadbank connection point actually is
A proper loadbank connection point is a dedicated, rated outlet — usually at ground or easy-access level — cabled back to the generator output so the test set plugs in downstairs.
The roof set stays where it is. The loadbank stays where a van can reach it. Nobody is feeding cable over a parapet like washing on a line.
On a rooftop life safety or standby install it should be in the design with the ATS, the flue and the attenuation — not remembered the week before the annual test.
Why rooftop sets need the test even more
Roof plant often runs fewer hours. Light load. Heat soak in a cramped enclosure. Cooling air that has to fight ducts and weather louvres. Those machines need a proper load, not a five-minute no-load run that makes a nice logbook entry and proves nothing about wet stacking or a blocked radiator.
If the only way to apply that load is a cable over the ledge, the test gets postponed. Postponed tests are how rooftop sets fail quietly until the first real outage.
What we tell clients
Specify a loadbank connection point on every rooftop generator
Size it for the set, protect it, label it, keep it accessible
Do not assume “we will drape something up on the day”
Then use it — annual loadbank, not just a start-up
We loadbank, we install connection points on new jobs, and we can add one to an existing roof set so the next test is a connection, not a cable run through the building.
If your generator is on the roof and the last “load test” was a man with a clip-on meter watching it tick over, you have not tested it. You have visited it.
01246 380525
GES Power Ltd — Loadbank the set. Don’t decorate the building with test leads.
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