Specifying diesel standby generators for homes

It’s becoming more common to see standby diesel generators installed in homes. For many properties the reliance on technology is no longer just to provide heat and light.

The demand for standby generators specified for these high end properties has increased by 60% as the option to provide continuous power becomes easier.

back up power for residential homesWhy choose a standby generator for residential use?

The main driver for residential generators is for properties in remote locations where power cuts are frequent. In these instances the main function of the generator is to keep lights and heating on, providing power for cooking and daily functions. Other considerations are to continue running services such as drainage pumps and security systems active.

Other specialist, but not so common, applications would be to keep swimming pools heated, fish tanks oxygenated, stables running with heat and light or provide full electrical support of a property at certain times of the year such as Christmas.


What sort of standby generator is required for a domestic property?

Below should give you an idea of what size generator And AMF panel you need if you wish to backup your entire mains supply.

 Mains Supply Size (Amps)
 1 phase or 3 phase
 AMF Changeover Panel Size (Amps)
Size (kVA)
 60  1 phase  60   17 (1 phase)
 100  1 phase  100   26 (1 phase)
 100  3 phase  100   88 (3 phase)
 200  3 phase  200   143 (3 phase)
300  3 phase  300   220 (3 phase)
400  3 phase  400   330 (3 phase)


How it works:

The first thing to establish is the power demand; that is how much power you need. You may be able to find the information from the meter; otherwise you could get it from your onsite or local electrician. Another option is to call in a specialist power supply company who can take the reading and advise the demand required.

The next part of the evaluation process is usually cost; how much will it cost? Realistic budget for permanently installed automatic generator, supplied, installed and commissioned is £250 per kVA.

However the usual rules of size vs price apply: the larger the generator, the lower the average cost. A small generator of around 33Kva will cost around £13,000 whereas a 100Kva generator will cost around £20,000.

Other considerations – Noise, exhaust smoke, looks, sizing it for future expansion of the building it is supplying.

Size of generator – A recent residential project had a demand in the region of 50Kva. A generator size for this type of application would be 2.4m x 1.1 wide 1.8 high.

Location – The generator needs to be installed on a solid base, usually precast concrete.

Cabling – Consideration should be given for the location of the cabling. If it’s to be hidden from sight (as is often required) trenching with be required which will add to project time and costs.

Noise – The impact of generator noise will vary depending on the location and proximity to the property. Consideration should be given for inner city generator installations which may be subject to noise and/or emission regulations.

Run time – The run time required for the generators impacts on many elements: the size of the generator, the size of fuel tank which then also relates to spatial requirements.

Spatial requirements – The size of both the generators and fuel tanks will dictate how much space is required for the physical items, but space should also be considered for maintenance access and repairs. In the ideal installation there would be at least 1000mm clear around the whole generator.

Refuelling access – How will the generator be accessed for re-fuelling? Is there potential for restricted access in poor weather? In some cases, remote properties may choose to add a bulk fuel storage tank to provide a reserve of around 2 weeks in case of severe weather.

Ongoing operational costs – These are mainly fuel and maintenance and will depend on the level of use. It would be a safe assumption to allow around £950.00 a year.

Future expansion of the property – It’s important to try and consider both physical and electronic changes to the property. Upgrading systems that require power may impact the power demand. Identifying areas that may develop will ensure that the generator is correctly sized to meet the demands of future expansion.

Unsure on your power requirements, request a site survey here or give our team a call on 0844 888 4445

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