back to article 'Leccy-starved Reg hack: 'How I survive on 1.5kW'

Here's a provocative question for readers in these power-hungry times: could you survive in a house where the total power draw of all your electrical appliances and fittings at any one time can't exceed 1.5kW? An overloaded kilowatt meter Preposterous, we hear you cry. Stick a load in the washing machine and put the kettle on …

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Buffering?

Don't ask me how, but could you have buffered the 1.5kW supply through some kind of storage device, allowing you to exceed the cap internally while the external supply never draws more than 1.5kW?

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Re: Buffering?

That could be done with lead acid batteries and an inverter of some description, but the initial cost of those, and the ongoing maintenance of them, would make it borderline I would think. But I'd certainly be looking at it if I were in that situation.

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Re: Buffering?

Thats what I was thinking.

A big stack of car batteries and an inverter to gvie you a bit of extra peak capacity juice

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Re: Buffering?

Also being located in Spain, a country with its fair share of sunshine, wouldn't hooking up some solar cells to those batteries also be in order?

Some friends down under have recently added similar to their house (sans batteries) and their electricity meter regularly runs backwards as often as it does forwards.

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Re: Buffering?

Never mind in Spain, I have solar panels here in good ole' Blighty, albeit only 1.1kW peak (that being as much as they thought they could safely fit on the south facing portion of my roof), and for much of last year, could gloriously watch as my main electricity meter span backwards during the day*. And I have a server, a PC and a laptop on 24x7 (along with assorted paraphernalia).

* except anytime I switched my 3kW kettle on :).

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Boffin

Re: Buffering?

Actually, car batteries are completely unsuitable for storage of electricity that you intend to use for more than about 10 minutes at a time. Car batteries are designed for short bursts of high output, namely starting your car. Deep-cycle or marine batteries are what you're looking for.

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Anonymous Coward

Re: Buffering?

"That could be done with lead acid batteries and an inverter of some description"

I thought that said: "That could be done with lead acid batteries and an inventor of some description"

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@CaptainHook -- Re: Buffering?

Easy and cheaply. Get a set of *old* forklift batteries for free (new ones cost a fortune). Forklift batteries are excellent as they've solid plates and even when sulphated and abused and no longer suitable for a forklift, they'll deliver many, many kilowatts.

Of course, you have to know how to 'load' them into the system. Helps muchly if you are an electronics nerd or know one.

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Re: Buffering?

I use 8D rebuildable "fire engine" batteries.

As a side-note, a fuel-sipping Generac QuietSource 22 kW generator can be had for under US$8750, in your choice of LPG or town gas, and easily converted from Town to LPG in a disaster bad enough to disable the Town gas supply. That's new, with full warranty, delivered, but not installed. We installed one for a friend a few months ago.

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Re: Buffering?

Just tape the breaker shut. As long as you stay below about 20kW there should be fairly little supra-requirement exothermic activity.

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Pirate

Re: @CaptainHook -- Buffering?

Easy and cheaply. Get a set of *old* forklift batteries for free (new ones cost a fortune).

Is hijacking a milk-float an option?

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Re: Buffering?

That could be done with lead acid batteries and an inverter of some description,

Commonly referred to as UPS. And there are these nifty load switchers that switch off one socket the moment you draw power from the other, kind like an inverted master-slave power strip. Meant to run your washing machine and your dryer, or a dishwasher and an under-the-sink kitchen boiler, off a single socket.

Judicious use of a couple of the above devices may keep the total load below the maximum available power, while the UPSes take care of keeping the essentials powered during popcorn-making or cement-mixing sessions.

BTW, the indicated microwave power is what is effectively radiated into your food; what is drawn from the mains can be double that.

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Re: Buffering?

..tape it shut..

Yup, my old fuse box was jammed full of pennies (The landlord may have been a bit dim in hindsight).

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Re: Buffering?

LOL

I like your thinking... Its Nuts but i like it

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Surely...

....a not as great picture but much more efficient LED TV would help, rather than the hungry beast that is a Plasma!

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1.5KW will barely run my computer setup... And printing using my laser printer would definately be out of the question. If I was rewiring a house, I would be looking to have a 100 amp 3-phase supply installed because running out of capacity is just primitive!

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Meh

Only 100 amp? Hardly seems worth the effort to convert to 3-phase if that's all you are going to install. I'd be looking at 200 amp minimum were I to go that direction, but as I've never felt constrained by my 100 amp standard residential service I don't really see ever needing to. Of course, if I ever decide to put in that machine shop in the garage, that would be a different matter.

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That's 100A per phase...

or the equivalent of a 300A single phase supply. A 200A three-phase supply (equivalent to a 600A single phase supply or 140kW) would be suitable for a medium sized light industrial unit (say 30,000 - 100,000 sq feet).

Also, your 100A residential service is probably only 80A or 60A. 100A is the rating of the fuse carrier. Most residences do not have a 100A fuse fitted. Many newer small houses in the UK with gas central heating, hot water and cooking have only a 40A supply (9.2kW).

HTH

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Re: That's 100A per phase...

And after a sparky got impatient and yanked the leftover cable through the distribution box, my previous company learned that (1) you get one hell of a bang when you cross the phases on a 200amp supply and (2) it turns out that mid-70s vintage 200amp ceramic fuses are extremely hard to get hold of now in the UK - our maintenence guy was scouring second hand electrical suppliers for some time.

They do however generally power an office building fairly well, until the fuse goes.

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Re: That's 100A per phase...

The other consideration is that while you can probably fit a 100A supply onto the existing grid, with a 200A supply, unless you live next door to a substation or industrial park, it's highly likely that you'd need to have the local transformer upgraded at (partially) your expense. Plus as I understood it the last time I looked, if you have more than a 100KW supply, then you have to have half-hourly metering.

When you say 300A equivalent, that's assuming 300A of phase-neutral loads which is insane, although I would love to see it in a domestic property! I would want it so that I can run a small workshop with proper equipment and perhaps a heat recovery A/C system.

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Happy

Re: That's 100A per phase...

You lot remind me of what my uncle did in the 1970s. He moved to an old farmhouse in a small village on the Lincolnshire coast and set up a shop selling pottery and various craft knick-knacks.

He is the only person I've ever known with three-phase electricity in his house, because the pottery kiln in the workshop in the back consumes more electricity than the rest of the village put together, or so I was told when I was much younger than I am now. The point being, so they say, that the electricity company has to balance the load on the three phases, so the kiln has to be spread across all three.

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Re: That's 100A per phase...

Aside from distributing the load across the phases, the other advantage is that you can get more power through a given size of cable. Take the 100A vs. 300A discussion. Using a table I found at http://www.energy-solutions.co.uk/cable_conductor.html, If I want to move 100A over a standard 70 degree armoured cable then I would need a cross section of 25 sq.mm but to move 300A over the same cable I would need a 95 sq.mm cable. Nearly four times the area to carry three times the current. This would be extremely expensive and would make wiring stuff very difficult (Try manipulating even a 35sq.mm cable into a distribution board)

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Unhappy

Re: That's 100A per phase...

I don't know what that would cost in the UK, but over here in Holland it's prohibitively expensive! We just had the three phase wired into the house (it was built with 3 phase, but only one is attached by default) as our new hob needs 480v.

The cost of the upgrade was not too bad at +-700 euros (you have to pay the network company for that). That comes with 3*25 amp fuses. If you want more than that (the next step is 3*80) then you have what they call 'KrachtStroom'. Then your monthly standing charge goes from 18 euros per month to 180 euros per month.

We stayed with 3*25 obviously! (Though with what we run on 3*25 amps, I can't imagine the electricity bill if we did need to triple our capacity ;p)

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RE: 100 amp 3-phase supply installed

Why would you want three phase for a residential load????

WRT the US, the common residential 3 phase voltages are 120/208 Volt Wye, or 120/240 Volt Delta.

If you are provisioned with a Delta service, then that third phase is useless for a single phase load, as it sits at 208 volts above ground.

If you are provisioned with a 208 volt Wye service, then any "240" volt loads are only going to see 208 volts phase to phase, an approximate 13% voltage drop from their nameplate rating with a correspondingly HIGHER current draw.

In some high rise buildings, a residence may be supplied by two phases tapped from a three phase Wye service.

You would be far better off using a 200 or 225 Amp 120/240 volt single phase service - unless you has a specific three phase load that had to be fed.

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Re: RE: 100 amp 3-phase supply installed

Im not sure about the US, but in the UK, three phase is 415 volts phase-phase and 240 volts phase-neutral for all three phases. The 4-bed detached house I live in for reference gets by just fine on a 60A single-phase supply.

If I was building a house though, I would want to add in certain luxuries that require three-phase power such as heat-recovery A/C (You can cool one room and heat another using the A/C system) and a workshop with professional tools (Decent metalworking lathes tend to be 3-ph even where they only have a 3hp motor)

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Re: RE: 100 amp 3-phase supply installed

Read the previous post - in big parts of mainland Europe (so not the UK), three phase is supplied to houses as standard to run 'big' consumers like electric hobs, washing machines etc.

Don't forget most folk live in apartment buildings too, not large detached houses typical of US suburbia.

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Re: That's 100A per phase...

That comes with 3*25 amp fuses. If you want more than that (the next step is 3*80)

Liander has a few inbetween steps and offer 3x35, 3x50 and 3x63 as well.

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Re: That's 100A per phase...

@Stoneshop! What! They never told me that (then again in the beginning they never said that there was anything other then the 3*80 either!)

Thanks, something to bear in mind should we add any other big kit :)

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Mainland UK officially 230V not 240V, and earthing is an issue

For many years now, the official mainland UK domestic single phase supply has been rated as a nominal 230V (with various tolerances, +10%/-6%, +/-6%, or +/-10%) rather than 240V. This is the same as the nominal supply for big chunks of continental Europe, whose nominal rating was increased from 220V to 230V at around the same time (perhaps with widened tolerances). Some overseas territories are still on 240V and 220V supplies.

(In practice, the measured supply at the socket is still likely to be closer to 240V in the UK, and 220V in much of the rest of Europe. Older UK equipment may specify a nominal supply of 240V. Equipment to be attached to the UK supply has to tolerate more than 250V. These ratings plates may explain why many think the official UK supply voltage is either 240V or 250V. Three phase supply is now supposedly 400V, although most three-phase warning plates still seem to refer to 415V.)

The article mentions adding a new earth. Adding a local copper earth to a modern PME supply can introduce lots of "interesting" high-current failure modes in the event that the supply cable develops a fault. It is always worth taking advice from the supply company and/or a qualified electrician before adding new earths and bonding points to a mains supply. Some earthing techniques that used to be common practice until quite recently are potentially lethal with a modern supply.

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Re: RE: 100 amp 3-phase supply installed

Decent metalworking lathes are typically run from a single to three phase invertor these days. You do not need or even want the high power availability of pukka three phase, if the tool catches in the workpiece your lathe will be in bits. Inverter drive also has the benefits of continuously variable speed, and soft start.

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Anonymous Coward

Dear Sir

Buy a generator.

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IT Angle

Re: Dear Sir

A Lister clone would give you a cheap 3KW, a generator that is a pleasure to own and work on and runs on just about anything, quietly and reliably. It's great for shop tools for when you're rebuilding the house and afterwards will happily sit in the garden for the next 5 years until you need it to start first time.

Which can be done with electricity, compressed air or just by hand. Thing of beauty imho but probably put on some guards as it can eat anything caught up in it without much bother but inversley won't get bogged down on initial peak loads.

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Adversity breeds ingenuity

I'm sure the El Reg commentards will come up with many useful and ingenious suggestions.

On e-bay, a 1.5KVA (continuous rating) diesel generator can be had, brand new, for £365. A brand new 5KVA generator is going for £650. Equivalent second hand ones would be cheaper, obviously.

These could be used for the outdoor power tools and maybe also an indoor immersion heater to provide a large quantity of hot water for use later in the day . Etc, etc ........

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Re: Adversity breeds ingenuity

The generator idea has legs, but it'd be cheaper to pay to have the meter moved in the end, something I'm trying to avoid.

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Stop

Re: Adversity breeds ingenuity

"Cheaper to have the meter moved"

Only if you don't put the genny back on ebay at the end, surely.

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Re: Adversity breeds ingenuity

I'm in a similar position, but with a place in the mountains just north of Madrid. Here a genny is useful anyway because the UPS won't keep the lights on for long in the winter. The UPS spools up at least once a week, and if there is a storm it will kick in several times.

As for ICP, in therory the property doesn't have one yet, because the contract hasn't been changed for about 20 years. There is a single incoming trip of 25A (3-phase) for everything and the swimming pool has an RCD, but that's it. Everything else is just an octopus of wires joined by twisting, with red, black, grey and white being used for all the lives and neutral (as in some sockets use 2 reds, some use 2 whites, etc.). Also some of the wire is smaller than I'd use for a doorbell. Don't ask about Earth; there isn't one...

I've found someone locally who will do the check and sign the boletín fairly cheaply, but first I've got to pull down the walls that need to be rebuilt, insert DPC in all the others and put in some insulation and heating. Meanwhile I'm living in a flat with a heady 3kW :)

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Go

Re: Adversity breeds ingenuity

To be honest, its always better to have a genny to hand if your off the beaten track a little.

We're about to enter the "extremely very cold" bit of winter here, and I have my little 1kw genny ready to run the central heating pumps for the wood burning heating system should it falter. A single bulb and the ability to stay warm while the leccy company takes a week to restring all the overline powerlines that fall down with the weight of snow is worth far more than you can measure in a simple cost of power vs fuel/generator calculation.

Future plans here include a 100kw 3 phase diesel backup genny on a skid off fleabay uk, because its really not cheaper to pay the higher tarrif long term for those few occasions we need more than 25kw 3phase...

Oh if you can get 3phase into your house but current limited, you'll have the fun "getting everything phase balanced" game, so the microwave isnt on the same phase as the washing machine etc. And if you dabble in home automation you too can find out how crap x10 3 phase filter units are (2 blown per year on average...)

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Re: Adversity breeds ingenuity

Actually, as many off-gridders have already discovered, it's far cheaper (about 10x) to decrease consumption instead of increasing capacity. New LED TVs for example, use about 1/3 as much power as Plasma. Microwaves and kettles can just be replaced with your gas stove. The cement mixer could run on gas instead.

Identify your biggest consumers, and reduce or eliminate how much they consume.

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Re: Adversity breeds ingenuity

@Phil 27

Yes, load balancing will be fun, but at least at the moment, the meter doesn't measure the imbalance, like the meters in England do. Cooking is changing from Propane, because the tank here requires the ministry of miners, plus the civil engineers, plus other crap that I don't want to have to deal with (including if you reduce your consumption, you have to pay them for what you don't consume to compensate them!). The new induction hob is a bruiser, but at least it is balanced 3-phase! The other major consumers are the well pump and swimming pool pumps which are both 3-phase.

First of all though, I have to get the structure sound, and insulated; heating system installed, internal walls etc. Power is a long way off except to operate demolition hammers :)

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Re: Adversity breeds ingenuity

Everything else is just an octopus of wires joined by twisting, with red, black, grey and white being used for all the lives and neutral (as in some sockets use 2 reds, some use 2 whites, etc.).

I had a house like that. Well, almost like that; the wiring colours conformed to the current standard, but whether a particular colour actually matched its use as proscribed in the standard had a probability of one in five. You could switch the stairwell light by hitting the plasterboard wall in a particular spot.

And this was right in the middle of a big city in the Netherlands.

Don't ask about Earth; there isn't one...

Err, right beneath you?

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Alert

too easy

A shed full of lead acid batteries an Inverter (and why not some Solar panels for a free daytime top up?) will solve most of your problems.

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Re: too easy

Basically.. a UPS. Kind of expensive though, unless you can pick one up secondhand from some failed business somewhere. Like a Spanish bank.

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Re: too easy

That or a proper off grid system, with deep cycle batteries.

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Re: too easy

Or fuel cells... Fuel cell for mains gas or even micro chp

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Anonymous Coward

Re: too easy@Parax

"Or fuel cells... Fuel cell for mains gas or even micro chp"

Speaking from a company developing propositions to sell such things, I would be very wary of recommending them. Micro CHP is IMHO all the complexity of the real McCoy with fewof the benefits and a fair few practical downsides, and fuel cells work well in a lab, but are much more problematic in the real world.

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Re: too easy@Parax

I'd only really recommend MicroCHP if you needed the heat and had battery storage to charge up with the power, microCHP is not a good generator, hence not my first suggestion for Spain. The fuel cells are being installed and are working very well if you have a clean gas supply.

But if you want to go back to basics there's always the Mains Gas Generator .

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If you're on a mountain...

... stick up a wind turbine. Probably get 500-2500W through that alone for a domestic unit.

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(Written by Reg staff) Silver badge

Re: If you're on a mountain...

Yeah, it's a top plan, but there are licencing problems. The local town hall takes at least year to grant permission to move a rock from one place to another. A wind turbine? The mayor would have a fit.

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Re: If you're on a mountain...

The standard Spanish methodology in this is to build first and ask permission later giving the "well, it's already done now" or "es completo ahora" excuse.

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(Written by Reg staff) Silver badge

Re: Re: If you're on a mountain...

It's true. I'm far too British about these things.

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