PowerSwitch

I'm looking for your thoughts on generators for essential services in a house during a power cut.

Obviously, the safety aspect is paramount, particularly with regard to isolating from the grid.

Where does a person start in looking at this preparation?

Consider the pros and cons of generator and battery system.

Step one determine how much power you need.
For a modest size and modestly equiped home I normally suggest about 4 kw. That allows 1 kw in total for the large number of low consumption lamps and appliances found in most houses. AND allows 3 kw for one heavy loading appliance.

For a larger and/or better equiped home I suggest about 7 kw, that allows 1.5 kw for all the small loads, allowing for more lamps and for some duplication of small appliances, AND also allows 5.5 kw for simultaneous use of two heavy loading appliances.

Step two, decide what fuel is be used.

Petrol generators are cheap, but the fuel is expensive and only 30 liters may be lawfully stored.
Diesel generators are more expensive to buy but more reliable and longer lasting. the fuel is cheaper and safer to store.
LPG has its merits if you already use this fuel and keep or can keep a generous supply. If you do not already use LPG, I would avoid the complication of adding another fuel type.

Step three. Decide how to wire it.
The simplest way is a changeover switch whereby the whole installation may be supplied from mains or generator. The drawback is that reliance must be placed on the human factor not to not overload the generator.

A better idea is to separate the existing circuits into essential and non essential, and fit the changeover switch only to the essential circuits, this is more work but prevents overloading by use of a cooker or a shower.

Another approach is to install dedicated generator only circuits, with no provision for mains operation. to supply one light in each room, two lamps in main rooms. These lights are not normally fitted with switches, they all light when the generator is running.
Also dedicated socket outlets, preferably green or blue. When the mains power fails the user has to unplug important loads from the normal, probably white outlets and instead use use the blue or green generator outlets.

Possible extra features worth adding.

One or more self contained emergency lights to provide some lighting instantly if the mains fails. Useful for bathrooms, kitchens, stairs, and the generator location. Make certain that these lights are connected to a generator backed circuit, in order that the inbuilt batteries will charge when the generator is running.

As an alternative to the above, consider a central 12 volt or 24 volt battery to supply basic lighting immediatly and automaticly in case of mains failure.
A single 12 volt leisure battery and a dozen 12 volt LED lamps can give basic lighting for 24 hours or more and saves running the generator at night for a couple of lamps. Make certain that the battery charger is generator supplied.

Consider fitting a current sensing relay in order that low priority loads such as an immersion heater can be automatically used when other loads are limited.

Purchase a couple of INTRINSICALY SAFE torches and keep them in two different safe places in case you need to handle fuel in the dark.

adam2 wrote: ↑11 Nov 2023, 00:29 Purchase a couple of INTRINSICALY SAFE torches and keep them in two different safe places in case you need to handle fuel in the dark.

Very good call Adam, I hadn't considered that.

Catweazle wrote: ↑12 Nov 2023, 00:18

adam2 wrote: ↑11 Nov 2023, 00:29 Purchase a couple of INTRINSICALY SAFE torches and keep them in two different safe places in case you need to handle fuel in the dark.

Very good call Adam, I hadn't considered that.

Did you hear about poor old Harry ?
What happened ?
Harry struck a match to inspect the level in his petrol tank.

Oh no ! you would think that would be the last thing he would do.
It was !

adam2 wrote: ↑12 Nov 2023, 02:08 Harry struck a match to inspect the level in his petrol tank.

Oh no ! you would think that would be the last thing he would do.
It was !

I know someone who did exactly that. He was about 15 years old, older brother was away in the navy, left a dirt bike in the shed that young Lee wanted to ride.

The shed went up, and took the dirt bike and more importantly his dad's entire deep sea diving equipment, suits, helmets, etc. he worked on oil rigs.

A very expensive mistake, but nobody was hurt.

adam2 wrote: ↑10 Nov 2023, 18:03 Step one determine how much power you need.
For a modest size and modestly equiped home I normally suggest about 4 kw. That allows 1 kw in total for the large number of low consumption lamps and appliances found in most houses. AND allows 3 kw for one heavy loading appliance.

For a larger and/or better equiped home I suggest about 7 kw, that allows 1.5 kw for all the small loads, allowing for more lamps and for some duplication of small appliance, AND also allows 5.5 kw for simultaneous use of two heavy loading appliances.

Step two, decide what fuel is be used.

Petrol generators are cheap, but the fuel is expensive and only 30 liters may be lawfully stored.
Diesel generators are more expensive to buy but more reliable and longer lasting. the fuel is heaper and safer to store.
LPG has its merits if you already use this fuel and keep or can keep a generous supply. If do do not already use LPG, I would avoid the complication of adding another fuel type.

LPG. we already use a pair of 34kg propane tanks purely for cooking. They last us about 8 months.

Which type is the quietest? During a recent power cut, a farmer ran his diesel generator for his milking machines and it could easily heard aver a kilometre away.

Petrol and LPG are generaly less noisy than diesel, but it varies a lot.
If possible place the generator in a brick or concrete built shed for security and noise attenuation.

Catweazle wrote: ↑12 Nov 2023, 00:18

adam2 wrote: ↑11 Nov 2023, 00:29 Purchase a couple of INTRINSICALY SAFE torches and keep them in two different safe places in case you need to handle fuel in the dark.

Very good call Adam, I hadn't considered that.

It would need to be T-class 4 or better, so 1-4 inclusive. Petrol auto ignites at 280, so T5 (300c) is insufficient.

I would suggest a couple of general purpose intrinsicly safe torches that are suitable for use in all common dangerous conditions.
https://evaq8.co.uk/energizer-atex-torc ... DkQAvD_BwE

emordnilap wrote: ↑10 Nov 2023, 12:44 I'm looking for your thoughts on generators for essential services in a house during a power cut.
Where does a person start in looking at this preparation?

Have the local drilling company decide to drill a shale gas well or two on your property, and then use leasehold gas to run natural gas appliances inthe house. You could install a natural gas fired generator to make electricity as well, but I never have. Its been working great for nearly half a century now on the property I've got.

To add to the points already made, if one or two 13 amp sockets are to be supplied from the mains normally, but with changeover to the generator, then it is recommended that these sockets should be RED in order to distinguish them from from standard "mains only" sockets.

Red 13 amp sockets may be obtained from the larger electrical suppliers, or on fleabay.

There is now a partial shortage of generators, both petrol and diesel types.
Believed due to the war in Ukraine, large numbers of generators have been purchased by the Ukrainian authorities, by individuals, and by charities.

Reasonable availability at full price, but fewer special offers and heavy discounts than in the past.

Far fewer sub £100 small petrol generators being sold in discount stores than in the past.