What kva size generator

4JAKE

Hey everyone..
Since the power cuts I guess I am like a lot of people and considering buying a generator.
I was lucky enough to have a good neighbour who had an Aldi power craft generator... He was good enough to let me run an extension lead and I used it to power the tv alone at night and he did the same...

So I was wondering what size Jenny would I need to look out for that could be wired in professionally at meter box that could be switched on and power the house to a reasonable level...

I'd like to have the tv, submersible water pump, oil burner working and few lights.

I don't mind not using showers, electric ovens or hob etc etc...

Any idea in what could be used???? Or is this a how long is a piece of string type of question

Irish Steve

Very much how long is a piece of string, and don't underestimate the cost of the change over switch at the meter, they are not cheap, as even if the generator is relatively low power, the switch and the wiring have to be able to take the maximum power that can be provided by your supply, which is usually a 63A fuse in the panel, and sometimes more now, possibly up to 80A main ESB fuse.

In terms of the house, the issue is making sure that large loads don't get used together, or at all in some cases depending on the power available, and that includes things like fridges, freezers, immersion heaters, hobs, fan heaters, kettles, washing machines, showers, tumble dryers, the list is pretty long.

Ideally, you need to do some quick sums and get the total wattage for the lights that you would expect to have active, the heating system, which means the boiler, and pump, and the other devices that are needed, like the TV, and any other devices that are wanted. Be careful with the submersible pump, they can take more to get them to start.

Having arrived at a power requirement, then decide if you want to be able to run anything else, ( a small kettle can be helpful) and that's the absolute minimum that you need from the generator, and ideally, the generator needs to have at least 25% reserve to allow for surges. While you may not want a cooker, or hob, if there's enough for a microwave, that can also be a useful standby, while most power cuts are relatively short, that's not always the case, as has been seen this week, there are some that will have been out for a week, and that's a very different scenario to provide cover for.

I has problems a long time ago (Rota power cuts in the UK in the 80's) with a small (1000W ) petrol generator that struggled to start the freezer compressor, even though in theory the freezer was only about 350 W, the start up surge to get the compressor going was significantly more, so that meant having to switch everything else off, and then turn on the freezer on, and hope it started, if it didn't, then it had to be turned off quickly to avoid damaging the compressor. It would start, just, most times, and the trick once it was running was to put it into fast freeze mode so that the thermostat didn't stop it, once it was running, then the other items like lights and TV could be put back on again, as the total load wasn't above the generator capacity. On occasions, to get the freezer to start, it was necessary to push the speed of the generator slightly above the normal governor speed, to make sure that when the compressor cut in, the voltage was there to get it to run.

Ideally, get a 1500 RPM diesel generator rather than a 3000 rpm petrol generator, the diesel will be quieter,(usually), and last longer, as well as being cheaper to run, (it can use heating oil, (gas oil, not kerosene) which is cheaper), and make sure that you run it regularly, and keep the fuel fresh, as otherwise it can be challenging to get it to start when the time comes that you really DO need it. Although it's more cost, and more maintenance, an electric start unit can save some muttering and problems.

It will be a compromise, unless you plan to spend a good bit more and pick up a second hand diesel unit that can run the entire house, that's a very different proposition.

Hope that helps

2011

4JAKE wrote: »

Since the power cuts I guess I am like a lot of people and considering buying a generator.

They have become very fashionable lately

I was lucky enough to have a good neighbour who had an Aldi power craft generator... He was good enough to let me run an extension lead and I used it to power the tv alone at night and he did the same...

I am always a little nervous about running expensive electronic devices from a small cheap generator.
Things like overvoltage (too high a voltage) or dramatic voltage fluctuations can cause catastrophic damage to sensitive electronics :eek:

However it would seem that everything worked out for you.
I am guessing from your post that your load was quite small and constant, both would have helped the generator to supply voltage within the correct specifications.

I was wondering what size Jenny would I need to look out for that could be wired in professionally at meter box that could be switched on and power the house to a reasonable level...

Generally speaking the generator change over switch would be located beside the existing distribution board (fuse box), not at the meter box (normally outside). That way it is indoors and the existing mains supply cable can be reused representing a cost saving.

I'd like to have the tv, submersible water pump, oil burner working and few lights.

Obviously if you have energy efficient lighting this will reduce the size of the load that the generator has to supply. You need to add up the total load of all of the devices. Generally a 6kVA generator would be large enough for what you have described. As a general rule though the larger the generator, the "better" the voltage output.

Make sure that everything that is not on your list is switched off / unplugged / isolated, and no 500W halogen sensor lights

Steve in the post above has made some good points.
I agree that the diesel generators are generally superior, but they may be over the top.
It depends on your budget, how often you are without power and how important it is for you to have electricity during a power cut.
I would guess that over the last 10 years I have been without electricity for less than 4 hours.

Steve mentioned something else that is very important, the generator change over switch. This as he stated must be rated to switch the entire load of the installation.
Even if the generator is small the switch will normally be carrying the entire load of the house. If this unit fails you are in trouble!
It is important that your electrician ensures that when the generator is connected and running that it is connected in such a way that it does not back feed the grid.
As a general rule, “big is beautiful” with switches such as this.
I have seen number installed where the switch is physically too small and this makes it difficult to get good connections and it can put strain on the terminals due to the spring on the cable.
I am installing a 45kVA (3 phase) generator at the moment, below is a picture of the changeover switch that I have installed.
By using a large switch I have make it easy to terminate.

4JAKE

Hey guys, thanks for the info...

We were without power for about 36hours... And were lucky I guess as some are still without it.

Our kitchen, hall, toilet, sitting room are all using down lighters but I have the 3w led bulbs so that brings down the wattage use suite low... 6 down lighters in kitchen = 18w rather than 240w

I understand that anything that heats water is a killer, so to try keep some form of a living standard... All
These items would be kept off... If the oil burner can be worked that will provide heat and even a bath if it's a long term power cut.
I actually bought a gas hob the other day to have as a back up so that at least we can cook and boil some water.... Other option was going to be the. BBQ..

I know that when the power cut happens everybody is in buy a generator mode and for maybe a week after... But then you forget the hassle and hardship..

But I am going to keep my eyes on the lookout for a generator at a good price over the next few months, maybe summer time, and buy it and just be more independent and prepared.

Perhaps I will even get to appear on an episode of dooms day preppers

Irish Steve

4JAKE wrote: »

Hey guys, thanks for the info...

We were without power for about 36hours... And were lucky I guess as some are still without it.

Our kitchen, hall, toilet, sitting room are all using down lighters but I have the 3w led bulbs so that brings down the wattage use suite low... 6 down lighters in kitchen = 18w rather than 240w

I understand that anything that heats water is a killer, so to try keep some form of a living standard... All
These items would be kept off... If the oil burner can be worked that will provide heat and even a bath if it's a long term power cut.
I actually bought a gas hob the other day to have as a back up so that at least we can cook and boil some water.... Other option was going to be the. BBQ..

I know that when the power cut happens everybody is in buy a generator mode and for maybe a week after... But then you forget the hassle and hardship..

But I am going to keep my eyes on the lookout for a generator at a good price over the next few months, maybe summer time, and buy it and just be more independent and prepared.

Perhaps I will even get to appear on an episode of dooms day preppers

It's times like this that being single fuel really bites, we were caught by the rota power cuts in the UK many years ago, and that meant that we were without power for 8 hours at a time on a rolling basis, and it went on for a while, 8 off 4 on at least 3 days a week, we had no other heating or cooking at that time, so that was when the small generator came on stream, to provide some supplies, along with a small bottle gas ring. I made a resolution then that I'd never again be caught with single source power for everything, so we have both electric and bottle gas cooking capability, and there are a couple of gas fires that can run on the bottle gas as well.

We ended up at the other end of the spectrum, I needed a backup for a computer system here, so ended up with a 30Kva 3 phase generator, which I've not taken out even though we don't have the computer here any more, as it's my flood standby for power to run pumps, one of which is 3 phase, and it is nice to have power even if ESB has gone walkabout.

The thing here is a big 5 litre 6 cylinder air cooled diesel, and I've set it up with auto start and shut down, if ESB fails, it's live within 2 minutes, and that's only because I run it for a minute off load to warm up a bit and stabilise the speed and smoke levels, and it then stays on load until ESB has been back for at least a minute, which avoids those nasty moments when ESB reset an area, and it crashes out again 5 seconds later, which is often when the most damage to equipment gets done, as there can be big surges in those events.

2011 will hopefully like this, I've attached links to some pictures of the panels on the system, domestic it is not , in that the house supply was moved when the 3 phase came in, ESB has a conniption about me wanting over 25Kw, the disc drives on the old computer that was in a dedicated air conditioned area of the garage were 6Kw surge for 7 seconds on start up, and if the power failed and came back before someone got to the room to prevent the discs from restarting, all 3 of them would kick in together, which wasn't ideal, they ended up having to be split across the 3 phases to balance the load. The biggest laugh is that in modern terms, I have memory sticks that hold 10 times as much as they did, they were 300 Mb each, and were the size of a small filing cabinet.

The house still has it's own separately switched feed, (via a 16Kva UPS,) the garage area is on a separate panel, and I can isolate one or the other, or both, which has been very useful on occasions when I've needed to modify something, but still have power available to do the job. That's why there are 4 contactors in the changeover, to keep the split between the areas.

Just been hearing on the news at lunchtime that it could be a number of days yet before some rural areas get power back, the longest we have ever had here was 18 hours a good few years ago, the main medium voltage 3 phase supply to the south of the town blew over in a gale, and there were "difficulties" with the farmer about access to put a new pole in, they ended up having to do a guy rope repair job on the broken pole for 6 months, and were only allowed to replace it after the crop in that area had been harvested. We have a better resilience now, the town has grown, so there's more than one route that power can come in by, but it did serve as a reminder that faults can and do happen.

Going back to your requirements, by the sound of it, a 6Kva would be plenty to run lights, TV, heating and have some spare for a microwave or small (1Kw) kettle, and it should be big enough to be stable and not get upset as things switch on and off, so with care, even a fridge or freezer would be supportable. If you are not worried about kettle or microwave, and can be selective about starting fridges / freezers, then probably 3Kva will cover you, though as 2011 mentioned, voltage stability with the smaller units is not as reliable as it is with the larger units.

Glad to hear you're back on again, I feel for the people that are without power, it's only when it's not there that you realise how much it's taken for granted these days.

https://www.dropbox.com/s/18dvvkdl3446s63/20140217_133831.jpg
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https://www.dropbox.com/s/anpd91b15bps15f/20140217_133908.jpg

4JAKE

We are all so dependent on it, it's actually almost like a near death experience when it's gone ..lol.

We built our home about 7 years ago so there is some fine tuning to be done,
I really don't like gas, I am very nervous of it leaking so I would never fully install it,
I am however either going to install the new gas hob in the utility room or garage... Probably garage... And only hook up the gas cylinder to it when it's needed...

It's amazing... Even enough power to pump water to fill your tanks so you can flush the toilet is a blessing... And to have tv... Well that's great when your in the dark from 5pm on..

Irish Steve

4JAKE wrote: »

We are all so dependent on it, it's actually almost like a near death experience when it's gone ..lol.

We built our home about 7 years ago so there is some fine tuning to be done,
I really don't like gas, I am very nervous of it leaking so I would never fully install it,
I am however either going to install the new gas hob in the utility room or garage... Probably garage... And only hook up the gas cylinder to it when it's needed...

It's amazing... Even enough power to pump water to fill your tanks so you can flush the toilet is a blessing... And to have tv... Well that's great when your in the dark from 5pm on..

That's what people forget until it happens, even things like water in the tanks is an issue if power is needed to get it there. We're urban as such, but if the power goes out, there are all sorts of things that can be a problem, even down to things like how do supermarkets trade, and keep their frozen stock safe if there's no power, there's very few places now that are not totally locked into bar code scanning tills that need power, so most of them have had to install some form of standby generator in order to be able to remain open when the power is out for any length of time. Several years back, the plant room at the local Supervalue caught fire, and destroyed their standby generator, and the fridge compressors, the first panic was for them to get as much as the freezer stock as possible moved to another store, while it was still frozen. They were out of action for some time, due to the damage, and more recently, Dunnes plant room caught fire, they were closed for while, with standby generators in the car park, when they were able to re open, the lighting was very limited, and there were very few freezers stocked, we can't recall how long it took to get it all back, but it was a number of weeks, and that was with no smoke damage to the store.

Gas, the simplest thing with the gas would be to have a lever valve in the line close to the bottle, (outdoors) and turn it off completely unless you need to use the gas, and have it hard piped into the utility. If you're nervous about copper pipe, there's no issue about using small bore galvanised gun barrel pipe from the cylinder to the house, and that's very strong, and unlikely to have any leak issues due to that strength.

I'd be reluctant to have gas in the garage, as there are other fire and ignition risks there that could be more dangerous than having a permanent supply into the utility room.

4JAKE

Irish Steve wrote: »

That's what people forget until it happens, even things like water in the tanks is an issue if power is needed to get it there. We're urban as such, but if the power goes out, there are all sorts of things that can be a problem, even down to things like how do supermarkets trade, and keep their frozen stock safe if there's no power, there's very few places now that are not totally locked into bar code scanning tills that need power, so most of them have had to install some form of standby generator in order to be able to remain open when the power is out for any length of time. Several years back, the plant room at the local Supervalue caught fire, and destroyed their standby generator, and the fridge compressors, the first panic was for them to get as much as the freezer stock as possible moved to another store, while it was still frozen. They were out of action for some time, due to the damage, and more recently, Dunnes plant room caught fire, they were closed for while, with standby generators in the car park, when they were able to re open, the lighting was very limited, and there were very few freezers stocked, we can't recall how long it took to get it all back, but it was a number of weeks, and that was with no smoke damage to the store.

Gas, the simplest thing with the gas would be to have a lever valve in the line close to the bottle, (outdoors) and turn it off completely unless you need to use the gas, and have it hard piped into the utility. If you're nervous about copper pipe, there's no issue about using small bore galvanised gun barrel pipe from the cylinder to the house, and that's very strong, and unlikely to have any leak issues due to that strength.

I'd be reluctant to have gas in the garage, as there are other fire and ignition risks there that could be more dangerous than having a permanent supply into the utility room.

I was basically thinking of fitting and removing the regulator from cylinder when not in use

Irish Steve

4JAKE wrote: »

I was basically thinking of fitting and removing the regulator from cylinder when not in use

Understood, for choice, I'd prefer not to be messing with the regulator on even an intermittent basis, in that the seals can be deformed, and a lever valve on the line is a better bet, as long as it is a gas rated valve, the beauty being that there's no tools needed to get the gas on, which can be an issue if there's no power, so no light, the easier the better/safer

sawdoubters

buy diesel it runs 4 times longer than petrol

you only need to keep fridge and lights going

make sure you run it outside

carbon monoxide poisoning

2-3kw


don't run electronics on it,you get surges

Irish Steve

A lot of modern electronics won't care much about voltage, as long as it stays within the tolerances that the suppliers are allowed, which are pretty wide, as per their reference information here

ESB Networks delivers electricity in a voltage range of 207 Volts to 253 Volts. This is in accordance with European Standard EN50160.

So, as long as the generator doesn't go above 253, there should be no issues, but, and this is a BIG but, a lot of smaller generators are set up to supply 240V, rather than 230V, which has been the European standard for a number of years, and this can put them closer to the upper end of the band than is good, as high voltage on sensitive equipment is often more hazardous than low voltage, sometimes simply because components are limited in the voltage they will tolerate.

The issue is that the UK was 240V, and in theory, it now is nominally 230, but for historic reasons, the suppliers have not dropped their 240 to 230, as it is still within the tolerance bands allowed by EU legislation, the UK works on a lower "upper" threshold, so that they remain within the limits outlined above that apply across Europe, as per the ESB page quoted. A lot of generators in Ireland are imported from suppliers in the UK, or supplied by companies that are UK based, so this tends to distort the availability of "genuine" 230 V devices.

Yes, it's a mess, as the real problems start to come to light when a device made for 230 V is used on a 240V supply, it will use more power than specified by the manufacturer, and also may run hotter. In the same vein, a device manufactured for 240 supply operated on 230 V will under perform, and this may be very noticeable on a microwave oven, where a small drop in the input voltage can result in a significant under performance of the device. It's one reason why European manufacture equipment may out perform UK manufactured equipment, even though in theory they are both designed to work on the same networks. The area where it gets really bad is on incandescent lighting, where a slight over voltage will dramatically shorten bulb life, and an under voltage results in poor illumination from the device.

It's more of an issue here in Ireland because we use the same system of plugs and sockets as the UK, so there has been a historic bias over the years in favour of UK manufacturers compared to European manufacturers, partly because of stupid issues like getting European manufacturers to make their equipment with moulded on UK style plugs, for a long time, they didn't, so that meant the importer either had to supply a conversion device to go with the European plug, or cut the European plug off and fit a plug suitable for Irish sockets, which in some cases caused warranty issues with the manufacturer.

The other factor that tended to favour UK manufacturers is of course the cost of shipping white goods to Ireland, the UK being closer has a significant cost advantage over Europe.

The page here even though somewhat out of date in some areas, makes interesting reading, and not a lot has changed, despite the passage of over 20 years since the change was officially agreed.

That said, it's less of an issue in more modern equipment, in that the 230 V input is dropped to a much lower voltage, and often also converted to DC, and that's not using transformers any more, it's using switched mode power supplies, which are well able to cope with the (relatively) slow changes at the normal 50 Hz from a generator.

The only thing that can cause problems is if the phase frequency goes significantly away from the nominal 50 Hertz, for some devices that use that as a time base standard, it can give some strange effects, the most noticable being bars of variable intensity that move up or down a TV display, but that's less common now than it used to be. There are not as many devices using the line frequency as a timebase as used to be the case, so it's not so much of an issue now, especially with the advent of higher frequency clock speeds used in high end spec display devices, it was very noticeable on older CRT technology screens.

Where small generators can be a problem is if they are heavily loaded, close to or slightly above their capacity, and the load is suddenly dropped to a very low level, then, there's a very likely chance of a voltage swing that will go outside of the allowed limits, especially if the speed governor is set slightly high, as can often be the case, even more so if they are set to operate at 240V to cover the UK case. That's one of the reasons I've suggested having at least a 25% over capacity capability on a smaller generator, it helps to avoid the issues of significant voltage swings that do happen on smaller units when heavily loaded.

OK, that was a bit of a wander round the parishes, but it hopefully explains why this is such a minefield, especially where generators are concerned.

Hopefully, it will also be a bit of background that will explain why some microwaves are not as efficient at others, which may come as a surprise to some people.

This is quite a good thread on the potential for a diesel gene. I'm sure it will shock and appall a few heads here. Good read if you can get through it.

It's a diesel gene. converted to start on WVO and run on solid lard, hybrid PV, wind generation system with battery storage. Eventually he adds heat exchangers to plumb through the house.

Combustion based electrical generators aren't the only kind of reserves folks.
I've been living on what I can generate myself the last 4 years, still haven't had a power cut. Admittedly I do outsource my workshop but that'll change in due time.