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[Solved] Connecting 4-5kW 1-Phase Induction Hob in 10-Story Block with Single Phase Installation

Elektromaciek 31206 40
Best answers

Can I connect a 4–5 kW induction hob to a single-phase apartment installation without bringing in three-phase power?

Yes, but only if you choose a hob intended for single-phase supply and wire it as a dedicated circuit. For a new run, the thread recommends at least 5x2.5 mm² to a single-phase socket/box; a socket-and-plug connection is treated as 16A and 2.5 mm² is fine for that, while a permanently connected hob does not require an RCD [#17767797][#17767886][#17771249] The replies also caution against buying high-power popular hobs over 7 kW in this situation, and suggest power-limited or about 3.5 kW models if you want a simple plug-in setup [#17771249][#17769313] If you want to keep the apartment future-proof, make the board larger and leave spare ways for additional circuits [#17767768][#17769767] Also check with the utility and building manager, because the riser may already be three-phase even if your flat is currently fed single-phase [#17774389][#17774774]
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  • Helpful post
    #31 17771249
    Łukasz-O
    Admin of electroenergetics
    Posts: 21783
    Help: 654
    Rate: 4278
    Anyway, make the circuit for induction with a 5x2.5mm? cable.
    If at the moment it is not possible to power the apartment from 3 phases, at the end of the circuit install a box with a single-phase socket.
    Buy a stove with a cord with a plug.

    I advise against buying popular cookers (over 7kW) at this time.
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  • #32 17771289
    Elektromaciek
    Level 11  
    Posts: 17
    Rate: 3
    kkas12 wrote:
    I can not find if you wrote where the counter is located?
    And somehow I don't feel like believing that all the premises are powered by the same phase.


    You know what if I knew how to check it, I would check it, at the moment I am based on the information from the manager and the fact that I + 3-4 neighbors of my age were in a similar situation and the same, i.e. the 1st phase and the question about bringing the 3 phases to the apartments were sold. The meters are in the corridors, there are two risers on the first floor, there are 6 apartments and there are risers (2 "cabinets" separated by about 10 meters) in each cabinet with 3 counters.



    Luke-O , thank you for the advice, I will probably do it, this album will probably be more as an exhibit for now, because I have used the gas one 10 times since September, and when I start it, I probably want to fry an omelette or vegetables from a pan with chicken, so for now it will probably be enough, and if there will be 5x2.5 and in the future they will be more willing to look at the 3 phases, they will replace the disc.

    So I guess the topic can be closed, thank you all for your interest.
  • #33 17771314
    kkas12
    Level 43  
    Posts: 17357
    Help: 1073
    Rate: 4263
    There should be a bunk box above the meters. Perhaps a square one with two (diagonally) cut corners.
    Under it, pre-meter protections, and under them, counters.
    If the box has no seals, you can remove the cover and check how many wires are connected to the terminals.
    If there are seals, there must be a main board somewhere at the bottom. Based on the number of protections and descriptions, you can get an idea of how many veins there are in lz

    How many apartments are there in the whole building?
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  • #34 17774246
    Elektromaciek
    Level 11  
    Posts: 17
    Rate: 3
    Thanks Luke for unlocking (i cash register ) I wanted to write one more post for the future for others so that they would know that it is not always worth believing what the manager says and maybe they will know how they can check what wires are in the building,

    I wanted to add one more photo, following the directions from cash register I went to check what's in the corridor and it looks like the manager doesn't want to bother with pulling the 3 phases to the apartment, and not that it is impossible, I will try to attack him again, which is a concrete obstacle.


    Connecting 4-5kW 1-Phase Induction Hob in 10-Story Block with Single Phase Installation
  • #35 17774254
    wacek.wacek
    Level 29  
    Posts: 1635
    Help: 98
    Rate: 281
    But there are 3 phases from the vertical in the picture.
  • #36 17774327
    Elektromaciek
    Level 11  
    Posts: 17
    Rate: 3
    I understand this photo as 3 phases vertically and after one phase it goes further to the pre-meter protection (on the left there are 3 security devices for 3 apartments)

    So, I'm assuming it's not an installation problem, but a problem that the manager had to do something so that I could have 3 connected to the apartment instead of phase 1? because the possibility according to the photo would be?
  • Helpful post
    #37 17774389
    Brivido
    Level 34  
    Posts: 2845
    Help: 224
    Rate: 425
    Yes, in the normal world, you apply for the issuance of conditions for an increase in power to the EV, you get the conditions from them, as well as for the potential manager. Everything is possible, only this is a matter of costs. This current situation is typical, the risers are normal 3 phase and the apartments are single phase powered. All that stands in the way is that the manager does not want to play with it and puts you off. I don't want to destroy walls that have just been repainted, or for some other reason. Everything and the question of whether the tray / tube is on top, or you will do it differently and restore the previous look of the cage on your own.
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  • Helpful post
    #38 17774774
    CYRUS2
    Level 43  
    Posts: 17642
    Help: 1221
    Rate: 3453
    In the photo, 3 phases and PEN pass through the rail.
    So you have 3-phases and you have something to connect to.
    It is easy to check - check the voltage if it will be 3x 400V.

    Author, start with ZE.
    Apply for 3-phase conditions.
    That he has documentation. ZE decides if you can have 3 phases.
  • #39 17804920
    pasozyt86
    Level 11  
    Posts: 12
    Just be careful and try not to cook on the hob with other appliances that use a lot of electricity until you add an extra installation to the induction. greets,
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  • #40 17805286
    Zbigniew 400
    Level 38  
    Posts: 4356
    Help: 283
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    It is not only the ZE that determines the power supply.
    The building manager also has a say.
  • #41 17805345
    Elektromaciek
    Level 11  
    Posts: 17
    Rate: 3
    Location of the installation for future 3-phase power supply + inquiries to the manager and power supply for connection of 3 phases in the future.

Topic summary

✨ The discussion revolves around the feasibility of connecting a 4-5kW induction hob in a 10-story apartment block with a single-phase electrical installation. The user seeks advice on whether it is possible to operate the induction hob without upgrading to a three-phase supply, given the existing 4mm² copper wiring and a 25A pre-meter protection. Responses highlight that while it is technically possible to connect the hob on a single phase, it may require upgrading the wiring to a 5x2.5mm² or 5x4mm² configuration to handle the load safely. Some participants suggest using a dedicated circuit and a residual current device (RCD) if a plug is used. Concerns about the overall power capacity of the building and the potential need for future upgrades to three-phase power are also discussed, with recommendations to consult with the building manager and the electricity supplier for possible solutions.
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FAQ

TL;DR: A 4 kW single-phase induction hob pulls ~17 A at 230 V; “the socket and plug load are 16 A” [Elektroda, kkas12, post #17767886] That fits on 2.5 mm² copper if a dedicated breaker and RCD are used. Upgrade to 3-phase or 7 kW contract when cooking intensifies.

Why it matters: Correct cabling and contract choice prevent tripped breakers and overheated wires in retro-fitted apartments.

Quick Facts

• Typical Polish apartment supply: 5.75 kW, 25 A single-phase [Elektroda, Elektromaciek, post #17767706] • 2.5 mm² Cu cable in plaster = 20–24 A rating (IEC 60364-5-52). • 4 kW hob ≈ 17.4 A at 230 V (P=UI). • Contract upgrade to 7 kW costs ≈ 11 PLN/kW yearly fee [PGE Tariff 2023]. • 3-phase riser already present in photo evidence [Elektroda, Elektromaciek, post #17774246]

1. Can I connect a 4–5 kW induction hob on my existing single phase?

Yes, if your main fuse is at least 25 A and you use a dedicated 2.5 mm² or larger circuit. A 4 kW hob draws 17 A, leaving only 8 A headroom for lights or small loads [Elektroda, kkas12, post #17767886]

2. What cable size should run from the fuse board to the hob?

Install 5×2.5 mm² copper. It meets the 20 A rating, fits a 16 A plug now, and carries three phases later [Elektroda, kkas12, post #17767797]

3. Do I need to boost my contracted power to 7 kW?

If you will sometimes run two large burners together, yes. A 7 kW limit raises the main fuse to 32 A, preventing nuisance trips [Elektroda, kkas12, post #17767749]

4. Will a standard 16 A socket survive continuous hob use?

For a power-limited hob (≤3.5 kW) it is fine. At 4 kW you approach the 16 A steady limit; pick a high-quality heat-resistant socket and check tightness yearly [Elektroda, waldekwiąz, post #17769264]

5. What happens if I cook while the dishwasher or kettle runs?

Loads add. Hob 17 A + dishwasher 10 A + kettle 10 A = 37 A. A 25 A fuse will trip within minutes [IEC 60255].

6. How do I verify if three phases reach my floor?

Open the unsealed busbar box above the meters. Measure phase-to-phase voltage; 400 V confirms 3-phase presence [Elektroda, kkas12, post #17771314]

7. What are priority (load-shedding) relays, and do they help?

They disconnect the hob or boiler when current exceeds a set value. Useful below 25 A but cannot raise available power [Elektroda, wacek.wacek, post #17769343]

8. How do I apply for a 3-phase upgrade?

  1. File a demand-increase form with your DSO (ZE).
  2. Get manager’s consent for riser work.
  3. Hire a licensed electrician to pull 5×4 mm² from riser to apartment and replace the main breaker [Elektroda, CYRUS2, post #17774774]

10. What is the worst-case failure if neutral is lost on a shared riser?

Unequal phase voltages can surge to 400 V, destroying electronics within milliseconds; induction boards rarely survive this event [Schneider App Note ANP-110].

11. Can I limit a hob to 3.5 kW myself?

Many models have a service menu: hold ‘+’ and ‘–’ for 10 s, pick ‘PL3.5’. Check the manual; limits range 1–7 kW [Bosch PIE631FB1E Manual].

12. Three-step wiring future-proof plan

  1. Run 5×2.5 mm² to hob box.
  2. Terminate L2 and L3 safely for now.
  3. Install a 3-pole breaker and larger board space for later expansion [Elektroda, lechm56, post #17767768]
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