In Israel, 40 amps is the maximum single-phase supply that the IEC (Israel Electric Corporation) will provide you with.
In the UK it is 100 amps which is equivalent to
the 200 amps available in the US.
In order to get more power in Israel, you have to' go three-phase'.
The average consumer has no idea what three-phase means except that it costs a lot of money and gives you more power.
It does cost a lot of money, but it doesn't necessarily give you more usable power
It is actually a bad solution. Apart from the expense of installation, it is difficult to install correctly. Essentially, the IEC (Israel Electric Corporation), which has a 100% monopoly on selling you electricity, is making you pay for power provision that you don't necessarily need and in most cases can't actually use.
Some years ago, I had to advise a potential launderette owner that the 4 machines that they intended using, which would have required just less than 60 amps, could not be connected in a balanced way to the IEC 3 phase 25 amp supply and that they would in fact have to order a 3 phase 40 amp supply at an additional overall cost of many thousands of shekels. In other words, to use 60 amps for his application, he would have to order exactly twice that.
When I raised this matter at an IEC conference in Jerusalem a number of years ago, Avraham Ziv, who was then the Jerusalem District manager of Network Applications at the IEC, explained that the decision to insist on the three-phase provision rather than a larger single-phase supply was made at the IEC. He provided no explanations but did accept that customers often need to order twice what they need.
40 amp Single-phase better than 25 amp three-phase
Here are just two examples, where a three-phase 25 amp supply is actually worse than the basic single-phase 40 amp supply even though you have almost twice the power.
If we take a modern electrical house which has,
say, 4 heavy-duty appliances each using 15 amps. The obvious problem is
that you have four appliances, but only three 25 amp phases.
So one appliance goes on each phase .... and one with nowhere to go.
Now you have to decide which two appliances to put on the same phase. This
means that they cannot be used simultaneously. Absurd? Absolutely! In this
case, you supposedly have a 75 amp supply, but you can't even operate two
basic appliances which together use only 30 amps!!
Had you not ``upgraded'' to a three-phase supply, you would have been
able to operate those two appliances together.
If you happen to have a heavy duty stove or electric shower, say from the UK, you simply would not be able to run them at all on a 25amp three-phase supply. You would however be able to run them on the basic single phase 40 amp supply - albeit with little to spare.
3-phase has other problems too.
* A loose neutral wire in your main fuse panel
will cause the voltage level on each of the phases
to swing violently depending on the loading. This is when your tv starts
smoking and
microwave burns out!
* The main fuse panel is much more expensive to install.
* It's possible to get a much greater shock before
the anti-electrocution detector (GFI / RCD)
trips.
* Dampness in a 3-phase fuse panel can easily causes burn-outs due to the higher voltage and standard use of 3-phase connector strips
It's interesting to note that whenever one orders
a three-phase upgrade, the flat has to undergo a pretty rigorous test where
all the outlets are checked, the grounding and electrical leakage are measured
and the customer foots the bill. For upgrading from 25amp to 40 amp single
phase, there is no testing done at all
.
So when is a 3-phase supply a good thing?
For a factory, or a workshop where more efficient three-phase industrial equipment is being used, or where a residential customer particularly needs it (say for a well balanced large electric cooling system) In the event, very few consumers have three-phase airconditioners even though they may have a three phase supply!
So why is the IEC so keen on 3-phase?
A number of reasons. Firstly, there are probably many in the IEC who
are not even aware of the problem. Those employees may well have very substantial
power supplies (provided at no cost) and would not even feel the disadvantages
of three-phase.
There are those who simply don't understand the subject and there is of course the issue of protectionism for the country's electricians and electrical engineers. Three-phase is a big money spinner. Anyone who has upgraded to three-phase will know of the hidden costs involved in getting the flat up to the levels required by the IEC and undergoing a pretty rigorous test.
The official reason is balancing the system. They seem to think that
the only way to balance the overall power network in the country (the national
Grid), is to balance everyone's flat!
The first thing to understand is that electricity is generated at the power station in three phases. Generators are very sensitive to imbalances in load between the 3 phases. In an ideal world, all appliances would work on a three-phase supply and there would be no imbalances in the system.
But three-phase washing machines, fridges, toaster ovens, microwaves, electric showers, dryers etc are not available.
In England and the US, a 3-phase supply is virtually unheard-of and yet the Electric Companies in these countries do not seem to have any balancing problems. The phases are balanced between streets or even between residential areas.
The IEC claim that the wiring is much more expensive and technically demanding for single phase. This is patently not the case. Let's take as an example, a block of flats.
The wiring to the building for the IEC high tension will be exactly the same. The wiring to each floor will be exactly the same. The only difference will be in the short distance between the floor junction box and each flat. A quick calculation shows that the additional cable cost to be about 40 shekels per flat!!
On the other hand, the flat will not need a 3-phase panel RCD, main breakers, 3-phase bus - a saving of hundreds of shekels on parts alone. The labour saving will be two or three times that amount.
So not only is there a nett SAVING to the customer, but he has a much more usable supply of electricity. He can turn on appliances without worrying which phase they are on. The only limitation is that he cannot turn EVERYTHING on at once. And let's face it, who turns the air- conditioning on at the same time as heaters?
Most people have a salary going into a bank account. Let us say for example that you were not permitted to go into overdraft, but if you did you would be slammed with massive bank charges (it is so in some countries)
Your employer turns around and tells you that from now on, you salary will be paid into three separate bank accounts. Imagine trying to ensure that none of the accounts goes into the red (blow a fuse)?
When you want to buy that large piece of furniture, the shopkeeper won't accept three equal cheques! - and you can't transfer funds between accounts (cross the phases) It would drive you up the wall. ``Why can't I have my salary paid in one large sum into one account? ``
It's time that the interests of the consumer come first. There is no justification in insisting that customers who require more power, have to order three-phase. The IEC should offer consumers the option of upgrading to 80 or 100 amps single-phase and offer a refund or a 'trade-in' to those customers who have already been forced to take 3-phase.
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Copyright reserved Jonathan Greenstein 1999
Jonathan Greenstein, an Associate Member of the
Institution of Electrical Engineers (IEE) and a council member of the IEE
Israel , is a consultant electrical engineer who has worked in the Telecommunication
and Electrical Supply Industries for over twenty years.