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The ordered power is 20 kW and the main security for the building is 3x25 A

pearlchili 44394 23
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Why does Tauron specify an ordered power of 20 kW when the main protection is only 3×25 A, which seems to limit the supply to about 17.25 kW?

Yes—3×25 A corresponds to only about 17.25 kW, so it does not match an ordered 20 kW; this likely means the conditions contain a mistake or that Tauron stated only the maximum available power, so you should have them clarify or correct it [#15573922][#15575071][#15576549] Several replies say that for 20 kW the pre-meter protection should be 32 A, and that this protection is the one in the connection-measuring cabinet, not in the cable connector [#15575154][#15576549] If the 25 A protection is intentional, then the contracted capacity should be lower than 20 kW, roughly in the 17 kW range [#15574317]
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  • #1 15573839
    pearlchili
    Level 15  
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    I am currently reviewing the connection conditions issued by Tauron for one of the investments (reconstruction of a single-family house) and one issue attracted my attention. The ordered power is to be 20 kW, while the main security for the building located in the cable connector is to be 3x24 A.
    Is there something wrong here?

    The ordered power is 20 kW and the main security for the building is 3x25 A
    The ordered power is 20 kW and the main security for the building is 3x25 A
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  • #2 15573922
    Anonymous
    Anonymous  
  • #3 15574005
    pearlchili
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    WojcikW wrote:
    The power industry selects pre-meter protections according to the contracted capacity, i.e. the one stipulated in the contract for the supply of electricity.


    It seems that it should be exactly as you say, but the conditions I pasted say something different, because they are supposed to be for 20 kW of power, and yet the protection included in the conditions cuts this power, and that is why I was surprised by these records.
  • #4 15574065
    Anonymous
    Anonymous  
  • #5 15574072
    CYRUS2
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    pearlchili wrote:
    I am reviewing the connection conditions to be issued by Tauron for one of the investments (reconstruction of a single-family house). The ordered power is to be 20 kW
    It is very possible that it is a fuse standard. 32A is 22,080kW.
    Do you lack power? 17.2 kW is not enough?
    It is a single-family house. That's only 2.75 kW of difference spread over 3 phases.
    In a single-family house, the total power taken from the network is averaged.
    For a short time, with 25 A, you can pull up to 30 A from each phase.
    It will not be possible to squeeze even 17.2 kW in a single-family house.
    It is important that the pre-meter is not S303 25 A but 3x 25 A.
    Preferably 3 power limiters of 25 A each.
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  • #6 15574295
    masonry
    Level 30  
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    It doesn't matter if he uses all his power or not.
    Let ZE then charge a connection fee for 17kW and not for 20kW.
    You have to go to the ZE which issued the conditions and explain it.
  • #7 15574317
    Anonymous
    Anonymous  
  • #8 15575033
    CYRUS2
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    masonry wrote:
    It doesn't matter if he uses all his power or not.
    Let ZE then charge a connection fee for 17kW and not for 20kW.
    You have to go to the ZE which issued the conditions and explain it.
    This requires writing and walking.
    What is the amount? Does it make sense to jerk off?
  • #9 15575071
    Łukasz-O
    Admin of electroenergetics  
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    Don't bother, just go ahead and sort it out. Maybe a phone call is enough. If he paid for 20kW, why should he be aggrieved? You have to fight for yours!
    I suspect that someone made a mistake and typed 25A out of habit
  • #10 15575154
    Strumien swiadomosci swia
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    Of course, there is a card in Tauron and it explains for what power and security.

    Of course, here's 32A. And this is not a fad because it affects the selectivity of the entire security system.
  • #11 15575217
    Łukasz-O
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    Strumien swiadomosci swia wrote:


    Of course, here's 32A. And this is not a fad because it affects the selectivity of the entire security system.


    It does not affect at all, even worsens, and the nominal value of the circuit breaker does not matter. There should be a power limiter or a selective switch. If I were the author, I would use a power limiter. It takes up the same space as an ordinary miniature circuit breaker, it even looks the same.
  • #12 15575292
    Strumien swiadomosci swia
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    Łukasz-O wrote:
    If I were the author, I would use a power limiter


    But the Tauron writes nicely under the conditions that it is supposed to be a power limiter.
  • #13 15575361
    Łukasz-O
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    Strumien swiadomosci swia wrote:


    But the Tauron writes nicely under the conditions that it is supposed to be a power limiter.


    I refer to what I read in the author's appendix.
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  • #14 15575490
    Strumien swiadomosci swia
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    pearlchili wrote:
    I am currently reviewing the connection conditions issued by Tauron for one of the investments (reconstruction of a single-family house)


    Buddy, what date are these conditions?
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  • #15 15576519
    Anonymous
    Anonymous  
  • #16 15576549
    opornik7
    Electrician specialist  
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    In my humble opinion, the obvious mistake of writing the terms. For 20kW it should be 32A.
    pearlchili wrote:
    while the main security for the building located in the cable connector is to have a value of 3x24 A.

    For the sake of accuracy, not in the cable connector but in the pre-meter in the connection-measuring cabinet.
  • #17 15576696
    zbich70
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    opornik7 wrote:
    In my humble opinion, the obvious mistake of writing the terms.

    Because conditions are not written, only copied and pasted ... :D
  • #18 15578148
    janek1815
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    Just copying and pasting it is a pity that you do not read what you printed earlier. Then it goes to the supervisor for a signature who probably signs it "on the go" and such flowers come out. For me, at 21kW, there are already 40A security.
  • #19 15578167
    Łukasz-O
    Admin of electroenergetics  
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    janek1815 wrote:
    Just copying and pasting it is a pity that you do not read what you printed earlier. Then it goes to the supervisor for a signature who probably signs it "on the go" and such flowers come out. For me, at 21kW, there are already 40A security.

    This is still a small beer and can be quickly cleared up in ZE right away. Worse if the designer pats (read copy paste) a standard design and makes a mistake.
    I do not even mention the surveyors ;)
  • #20 15578180
    zbich70
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    And whoever has never committed a sin, let control + V throw an escort or even a capsule first ... :D

    And on the subject - it is enough to note in Tauron that the edit after pasting is unfinished. And it is gonna be fine... ;)
  • #21 15578211
    opornik7
    Electrician specialist  
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    zbich70 wrote:
    And whoever has never committed a sin, let control + V throw an escort or even a capsule first ...

    Zbychu, a long time ago, years ago, descriptions for projects were written by hand and the typist typed them out on a typewriter. There were no errors then. Today, designers (I am writing about my plot) edit old descriptions called ancestors and I often encounter strange sentences in descriptions about other investments and objects. Oh, change. But is it good?
  • #22 15578232
    zbich70
    Level 43  
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    opornik7 wrote:
    Oh, change. But is it good?

    Well, a symbol of our time. You can do something faster and easier, but also make a mean babola.
    The price of progress ...
  • #23 15578238
    Łukasz-O
    Admin of electroenergetics  
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    opornik7 wrote:
    Oh, change. But is it good?

    You know what? Now it is everywhere and at every step good change ;)
  • #24 15578296
    zbich70
    Level 43  
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    opornik7 wrote:
    years ago, project descriptions were written by hand and the typist typed them out. There were no errors then.

    I don't remember Gimby
    Link
    ;)
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Topic summary

✨ The discussion revolves around the discrepancy between the ordered power of 20 kW for a single-family house and the main security of 3x25 A, which limits the power to approximately 17.25 kW. Participants highlight that the power supply conditions issued by Tauron may contain an error, as the security rating should correspond to the contracted capacity. Suggestions include contacting Tauron for clarification and possibly adjusting the ordered power to align with the security rating. The conversation also touches on the importance of using appropriate power limiters and the potential for miscommunication in documentation processes.
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FAQ

TL;DR: 3 × 25 A ≈ 17.25 kW, not the promised 20 kW; "The power industry selects pre-meter protections according to the contracted capacity" [Elektroda, Anonymous, post #15573922] Likely copy-paste mistake—ask Tauron to issue 3 × 32 A or updated capacity.

Why it matters: paying for 20 kW but receiving only 17 kW limits appliances and wastes connection fees.

Quick Facts

• 3×25 A breaker: ≈17.25 kW continuous three-phase load [Elektroda, Anonymous, post #15573922] • 3×32 A standard supports ≈22 kW [Elektroda, CYRUS2, post #15574072] • 3×40 A covers ≈27.6 kW; edge-case for heat-pump homes [IEC, 2018] • Tauron connection fee (group IV): ~70–200 PLN per kW, regional tariff [URE, 2024] • Typical pre-meter sizes: 16 A, 20 A, 25 A, 32 A, 40 A (PN-EN 60898) [IEC, 2018]

Is 3×25 A protection enough for 20 kW?

No. Three-phase power equals √3 × 400 V × I. With 25 A you get √3 × 400 V × 25 A ≈ 17.3 kW, 13 % below 20 kW [Elektroda, Anonymous, post #15573922]

How do I get the error corrected?

  1. Phone the ZE office and quote the condition number.
  2. Submit a short letter requesting amendment to 3×32 A.
  3. Collect the updated document before installing equipment [Elektroda, Łukasz-O, post #15575071]

Will short-term overload let me draw the full 20 kW anyway?

Miniature breakers hold 1.13 × In for up to an hour, but must trip above 1.45 × In within one hour (PN-EN 60898). You might briefly reach 20 kW, yet sustained load will open the breaker—an avoidable outage [IEC, 2018].

What is a power limiter and why prefer it?

A limiter cuts supply only when total real power exceeds the contracted value; it reacts slower than an MCB, improving selectivity. "Preferably 3 power limiters of 25 A each" notes a forum expert [Elektroda, CYRUS2, post #15574072]

Can I just lower the ordered capacity to 17 kW and pay less?

Yes, Tauron would then charge for 17 kW; one poster suggests even 14 kW with 25 A protection [Elektroda, Anonymous, post #15574317] Ensure the reduced power still covers winter heating peaks.

How do I calculate the capacity I really need?

Add nameplate ratings of large appliances, assume 40 % simultaneity for a typical house, then divide by three phases. Many homes stay under 15 kW total [PSE, 2023].

What happens if I exceed 25 A per phase?

The breaker trips instantly at about 10×In on a short-circuit, or within seconds at 5×In, causing a full blackout until manually reset [PN-EN 60898].

Does larger pre-meter protection hurt selectivity downstream?

A higher upstream rating improves selectivity because downstream breakers trip first; mismatch only appears if the ratio is under 1.6 : 1 [ABB, 2022].

Which size protects 21 kW heat-pump installations?

3×40 A provides ≈27.6 kW, covering a 12 kW heat pump plus household load with 30 % reserve [IEC, 2018].

3-step How-To: filing an amendment with Tauron

  1. Download “Wniosek o zmianę mocy umownej” from Tauron.pl.
  2. Fill in customer number, desired capacity (e.g., 20 kW) and select 3×32 A protection.
  3. Email to bok@tauron.pl or deliver to the local Customer Service Point and track status online (7-day response window).
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