Why a Residential Load Assessment Comes Before We Quote a Generator
A lot of homeowners are quoted a generator from one number: the main fuse. 60 A, 80 A, 100 A — pick a kVA that “covers the supply” and hope.
That is how you buy a set that is too small for the heat pump and the freezer starting together, or far too big for a house that only needed lights, the boiler and the fridge.
GES Power Ltd start the other way. We ask what you actually want to keep running when the mains fails. That is what the Residential Standby Generator Load Assessment Form is for.
Click here to download the GES Power Ltd Residential Standby Generator Load Assessment
Form.
Print it, tick what must stay on in a power cut, and email it to hello@generator-man.co.uk. Typical wattages are printed as a guide. If you know the nameplate rating, write that instead.
The form is not the final design. It is the conversation, on paper, before anyone talks kVA.
Three levels of cover — not one mystery size
The most important question on the form is what you want the generator to cover:
Essentials only — lights, boiler, fridge, broadband, sockets for phones or medical kit
Comfort backup — essentials plus heating, selected kitchen appliances and the home office
Whole-house standby — as much of the property as the supply and the budget will allow
Not sure yet — we recommend a sensible size after the form and a site survey
Until that is answered, a quote is a guess.
Why heating and “big ticket” loads decide the size
Section 4 is where most homes are won or lost.
A gas boiler’s pump and ignition are a couple of hundred watts. An air-source heat pump is kilowatts, with a hard start. An electric shower is 8.5–10.5 kW on its own. A 7.4 kW EV charger, an immersion, a sauna or a hot tub — any one of those can double the set you thought you needed.
Tick only what must run in an outage. Many homes keep showers, EV charging and the cooker off the generator, or run them one at a time. That is load management, not a smaller lifestyle. It is how a sensible standby set stays sensible.
Starting surge is not running watts
A fridge might run at 150 W and pull 800 W when the compressor kicks in. Gates, borehole pumps, sump pumps and heat pumps do the same.
We do not add every start together and call that the generator. We size for running load plus the largest likely start, then apply an operating margin and convert to kVA at 0.8 power factor — the usual standby rating. That is written on the form so nobody is surprised later.
A reading on the incoming tails will not tell you that. Neither will a brochure that says “whole house” and shows a kettle.
What happens after you send it back
Click here to download the form if you have not already.
Return it to hello@generator-man.co.uk or call 01246 380525. We estimate selected running load, the biggest motor start, whether load shedding is needed, and a recommended set size.
Then — if you want to proceed — a GES Power Ltd engineer does a domestic site survey: supply, consumer unit, siting, access, noise, neighbours, planning. Final size, fuel, ATS / changeover and position are confirmed there, not from the form alone.
The form stops us quoting a 20 kVA set for a house that needed 8 kVA of essentials, and it stops us quoting 8 kVA for a house with a heat pump, an EV charger and no intention of turning them off.
Who it is for
Homeowners who are tired of outages. Anyone with medical equipment, a home office, a chest freezer full of food, or a heat pump that dies when the grid does. Anyone who has been given a kVA over the phone with no list of loads behind it.
Fill it in honestly. Tick what you care about. Leave the electric shower blank if you can live without it for a few hours. That honesty is what lets us specify a machine you will actually use.
GES Power Ltd
01246 380525
Sized for what you tick. Not for what looks good on a leaflet.
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