Installation of a generator for a house.

I would favour a diesel generator over other fuels.

Diesel is much cheaper to run than petrol, and a lot safer to store. The law sets strict limits on petrol storage, but almosy any amount of diesel may be stored.

Propane is only worth considersing if you going to use this fuel for other purposes and keep a large stock.


Automatic start and changeover adds considerable cost and complication. I would favour push button electric start, and a manual change over switch.


I would suggest a continual rating of about 4.5 to 5 Kw for most domestic standby purposes.

This will allow almost unlimited use of lighting, refrigeration, central heating, IT stuff,  entertainments and other low loading items. Allow up to about 1.5 Kw in total for such loads. This will also permit use of JUST ONE heavy loading appliance such as a washing machine, a tumble dryer, a kettle, a portable heater, a table top electric cooker, a power tool, or a vaccuum cleaner. But ONLY ONE such appliance at a time.


I would install two consumer units, one for "mains only" circuits and one for for "mains with changeover to generator" Use red 13 amp sockets on 4 amp circuits for the generator backed circuits. Use these outlets for all or most low loading appliances. The 4 amp MCBs will deter use of heaters and kettles. 1.5mm cable would suffice, but I would use 2.5mm in case you get a larger generator and want to uprate these circuits to 20 amps.

In the kitchan, fit ONE SINGLE red 13 amp socket on a 10 amp MCB, this to permit use of JUST ONE heavy loading appliance. A 10 amp MCB will supply almost any portable appliance that has a 13 amp plug. A bigger MCB than 10 amps will encourage use of "death cubes" and multiple appliances. In case a heavy loading appliance is needed in another room, provide a heavy duty extension lead with a SINGLE outlet.


Connect to the generator backed consumer unit the following.

All lighting.

Central heating.

Any dedicated circuits for fire alarms or intruder alarms.

Anything else useful or important and of low loading.

4 amp power circuits as described above.


Connect to the mains only consumer unit the following.

Electric cooker.

Electric shower.

General purpose (white) 13 amp power sockets on standard ring or radial final circuits.

Anything else of high loading.

Mains into the generator changeover switch.


Install a few self contained emergency lights on the lighting circuits to light the exit routes and also to light the generator and changeover switch. Make certain that these emergency lights are on a circuit supplied by the generator, in order that they will charge when the generator is started and therefore still be nearly fully charged if the generator trips or breaks before the mains supply is restored.

I would favour a diesel generator over other fuels.

Diesel is much cheaper to run than petrol, and a lot safer to store. The law sets strict limits on petrol storage, but almosy any amount of diesel may be stored.

Propane is only worth considersing if you going to use this fuel for other purposes and keep a large stock.


Automatic start and changeover adds considerable cost and complication. I would favour push button electric start, and a manual change over switch.


I would suggest a continual rating of about 4.5 to 5 Kw for most domestic standby purposes.

This will allow almost unlimited use of lighting, refrigeration, central heating, IT stuff,  entertainments and other low loading items. Allow up to about 1.5 Kw in total for such loads. This will also permit use of JUST ONE heavy loading appliance such as a washing machine, a tumble dryer, a kettle, a portable heater, a table top electric cooker, a power tool, or a vaccuum cleaner. But ONLY ONE such appliance at a time.


I would install two consumer units, one for "mains only" circuits and one for for "mains with changeover to generator" Use red 13 amp sockets on 4 amp circuits for the generator backed circuits. Use these outlets for all or most low loading appliances. The 4 amp MCBs will deter use of heaters and kettles. 1.5mm cable would suffice, but I would use 2.5mm in case you get a larger generator and want to uprate these circuits to 20 amps.

In the kitchan, fit ONE SINGLE red 13 amp socket on a 10 amp MCB, this to permit use of JUST ONE heavy loading appliance. A 10 amp MCB will supply almost any portable appliance that has a 13 amp plug. A bigger MCB than 10 amps will encourage use of "death cubes" and multiple appliances. In case a heavy loading appliance is needed in another room, provide a heavy duty extension lead with a SINGLE outlet.


Connect to the generator backed consumer unit the following.

All lighting.

Central heating.

Any dedicated circuits for fire alarms or intruder alarms.

Anything else useful or important and of low loading.

4 amp power circuits as described above.


Connect to the mains only consumer unit the following.

Electric cooker.

Electric shower.

General purpose (white) 13 amp power sockets on standard ring or radial final circuits.

Anything else of high loading.

Mains into the generator changeover switch.


Install a few self contained emergency lights on the lighting circuits to light the exit routes and also to light the generator and changeover switch. Make certain that these emergency lights are on a circuit supplied by the generator, in order that they will charge when the generator is started and therefore still be nearly fully charged if the generator trips or breaks before the mains supply is restored.