Potentia of electricity

[Sailor]

Hi all,
We have moved here from OZ in June and are having some queries re the required potentia that is required for the average 3 bedroom 156 m2 villa in the Manilva area. The previous owner had a contract for 13.2 KW but the Airconditioner blew the fuse outside after 20 minutes running and the electrician advised that we need more potentia. so we upped it to 15 kW but the costs are now very high, just the standing charge each month is 125 EUR plus the usage, last bill 186 EUR.
I hear some people saying that 10 KW would be enough with a more modern inverter aircon unit, which I know use a lot less power, we only need it in July and August really and the odd day for a short while to heat.
Any advice, ? The electricians seem reluctant to commit themselves
Thanks
Rainer

[Enrique]

Hi Sailor,
Look on Unit and see what it is rated at...............maybe there is a fault with the unit if its lower than 13.2Kw.

I'm glad we can get by OK on 3.3Kw with the cost of Electricity these days...............

[Wicksey]

That must be some aircon unit! Did you have other high usage things on as well .... an electric oven and hob uses a lot of power, but even then, 13.2kw sounds a huge amount to me (like Enrique we manage on a low potencia of 4.4kw).

[El Cid]

You have a three phase supply as it is over 10kw.

That means that you also have a three phase ICP so you can only use about 5kw on each phase. If the AC units are on the same phase as other high wattage items then it is entirely possible that you can trip the ICP. It's a crazy situation as you are paying to use 15kw at any time, but effectively you cannot.

I am in the same situation and I am seriously considering downgrading to a 10kw single phase supply where I will actually be able to pull 10kw when needed.

Sid

[ebbnflow]

We did exactly what Sid said above. Dropped from 13.5 three phase to 9.5 single. Big savings on the leccy and had no problems with usage.

[El Cid]

What exactly was involved in doing that? Any problems with organising it?

Sid

[TorreDelAguila]

Do check out the Wattage of your AC units, and tot them up.

Many properties in this part Spain have 3-phase supplies (often quite unnecessarily), and the way circuits in the house are allocated to the phases can only be described as totally haphazard!

When we took possession of our 2001-built campo villa, there was a 13kW potencia, ICP'd at 3 x 40A.
Sounds ok, but in reality it was dangerous and chaotic. One bathroom had a double socket outlet above the basin, each socket on a separate phase, with the mirror lights above on the third phase! That puts almost 400V into your wet shaving area! Words fail.

We also discovered that 80% of the house, including 32A (theoretical max) of under-floor heating, was hooked into just one phase. A second phase carried just that bathroom mirror light, plus one single powerpoint!

We quickly sorted things out at the fuseboard/consumer unit, and a couple of wall junction boxes, to give a more equal loading across the three phases, as it should be. We also made sure that no more than one phase was present in any one living/working area, again as it should be.

I have lost count of the number of domestic properties I have seen where the allocation of wiring circuits was obviouly left to the electrician's monkey, then signed off (Bolletin issued) by said electrician. It seems that the test of proper wiring is "if it lights up, it's ok". Most qualified UK Electricians I've met here are simply appalled, much of which, in the UK, would be regarded as criminal.

[El Cid]

We did all that, balancing all three phases, but whatever you do, the contracted potencia is way above what you can actually use in practice.

I was hoping that the new digital meters will allow the full usage across all phases, but from what I have been told, it will stay the same as it is now.

I will wait until the new meter is installed and see if that is correct, but I doubt it.

Sid

[TorreDelAguila]

I don't think the new meters (we have one, and obtained a full manual for it from the French manufacturer) have the facilty to switch loading across phases. Sophisticated energy and supply logging, yes, and the ability to cut off supply remotely, but phase-switching is something else, requiring some pretty heavy-duty control circuitry.

The point about being able to contract for a potencia above that which the installation can deliver is a very good one. I doubt Endesa will do much to discourage this!

[El Cid]

I don't see why it should be so difficult. There is no switching involved, just measuring the overall load across all phases. When that is exceeded, then the whole supply would be tripped, which is what happens at the moment when just one phase exceeds the load.

I think it is done that way because it forces users to contract for more potencia. They are already charging us a much higher rate, both for the potencia and the usage, than a single phase supply - just commercial greed in my opinion!

Sid

[Sailor]

Thank you for all your replies, it certainly gives me new food for thought. Yes I am on 3 phase and the news that each phase is measured and one can only get 1/3rd of the potentia contracted is a very important point. My Airconditioner is not that big, it's a ducted system of 30000 BTU,s, in OZ I had 3 times the size in a much bigger house but it ran on 415volts 3 phase and the rest of the house on single phase.
The problem to go from 3 phase to single phase which I would like to do is that apparently the wiring has to be increased due to the higher load if done properly. Any thoughts on that?
Thanks again
Rainer

[El Cid]

My understanding is that the maximum load that you can put on a single phase domestic supply is 10kw. It's not your cables that are the issue, it is the size of the supply cables from the street.

Certainly, when we built our house and wanted U/F heating, which is rated at 17Kw, there was no alternative to 3 phases. At that time, if you had a dual tariff an ICP was not required, in fact, if you had one it was removed. The rules changed some years ago and ICPs are now compulsory.

Sid

[Sailor]

Thanks El Cid, you are right re the max that you can put on a single phase, so I stick with my 3 phase even though the max per phase is 5 kW and hope that it will drive the new aircon.
The cooker and disho are on other phases.
See how we go.
Cheers
Rainer

[ebbnflow]

What exactly was involved in doing that? Any problems with organising it?

Sid

We were due modernising work on the system anyway, so things like a completely new consumer box were on the cards already so we took advantage of that to make the change. Our electrician back then was Sevillana certified/licensed for such work so prodused the new boletin as well. The change was confirmed on our bills from Sevillana on the next full period. The old supply line was not replaced, just converted to single phase, at our request in case we sold and new owners wanted to reverse the process.

To be fair I'm unsure how much was due to the phase change or to the modernisation.

[spanish_lad]

(used to be an electricians mate)

physically, the work involved in changing from 3 phase back to single is actually very easy. (while it really shouldnt be done like this, it normally is, or at least used to be.

Imagine, in your heads..a single supply is simply a 3 phase supply with only one supply being used. most houses, or at least streets actually have 3 phase already in the floor on on the pylons.


imagine this:

3 cables in the street - into the house into 3 fuses at 5kw - into the back of your fuse box and one cable wired to each "bank" of fuses (or thats how it is normally).

to make that into a single supply.. it´d be 1 cable in the street - into the house into 1 fuse of 10kw - into the fuse box and then the 3 banks joined together. the other two cables in the street just get a chocolate block on the end and taped up

"most" of the cabling / connectors etc are pre-installed for 10kw so theres no need to change anything like that.

[El Cid]

Thanks to both of you, it does sound simple, but of course sorting out the contractual changes with Endesa/Iberdrola could be fun!

Sid

[Sailor]

Hi guys,
Some more news, I had a new inverter aircon installed which works easy on the 5 kW of one of the 3 phases so I wanted to change back from 15kw potentia to at least 13.2 like before if not to a single phase 10 kW potentia and Fenia the retailer advised that by law I can only change once a year!
Had I known that I would have done more research now I am paying huge standing charges till next August. Is there an Ombudsman here for problems with utilities companies as we has in good old OZ.
Cheers
Rainer

[TorreDelAguila]

How do the two standing charges, 15kW and 13.2kW, compare?

[El Cid]

They are directly proportional as the standing charge is per kW.

Sid

[Sailor]

Hi guys,

I have now sorted out with the help of an Irish friend ,( electrical guru) that I will change from my 3 phase 15 kWh potencia to a single phase 9.2 kWh potencia and had a quote to do the work from Rafalux for EUR 695 incl a new meter with surge protection.
I live in a villa and the have to bring in new cables from the meter box in the street to my switchboard in the house.
Sounds reasonable?
Thanks for your help,
Cheers
Rainer