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High Household Voltage Fluctuations: Experiences & Changes in Polish Power Grid Since 2013

barytek 23895 33
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Why does my household mains voltage stay around 237–248 V and sometimes change by more than 15 V, especially before and during a storm, and is that normal?

Yes, voltages of 237–248 V are still within the permitted mains range of 207–253 V, and 253 V is an average over the measurement period, not a hard instantaneous ceiling [#15212297][#15212465] Such fluctuations can be normal on the low-voltage network, especially near the transformer, and a storm can change the load or even switch network sections, causing the voltage to rise or fall quickly [#15213572][#15213827] If you suspect a real problem, ask the utility to check the neutral/PEN connection and the installation, because a bad neutral can cause abnormal voltages in a three-phase system [#15212666][#15213163] The most useful next step is to request a recorder/analyzer so the voltage is logged 24/7 instead of only during a daytime visit [#15216179][#15216979] With recorded evidence, the supplier can decide whether to adjust transformer taps, replace faulty wiring/poles, or otherwise correct the network [#15212340][#15216979]
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  • #1 15212254
    barytek
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    This topic has already been discussed, but in 2013 and since then, a lot has changed in the Polish power grid.

    In October I had a reconstruction of the low voltage power grid on the street. Constant power outages prompted me to buy a UPS. Until then, I was convinced that the mains voltage should be around 230V + - a few volts. Meanwhile, the voltage is usually from 237v to 248v for me, 244v most of the time. There was a small thunderstorm at the end of November. Just before the storm, the voltage exceeded 250V, the UPS switched on voltage stabilization. When it started to rain, the voltage dropped very quickly by over 15V. I will add that the house is located 400m from the transformer. Do I alone have such high voltage fluctuations? The voltage comes from the UPS
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  • #2 15212297
    jharlan
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    The permissible deviation is +/- 10%, i.e. from 207V to 253V.
    barytek wrote:
    Do I alone have such high voltage fluctuations?

    Not
    barytek wrote:
    Just before the storm, the voltage exceeded 250V

    barytek wrote:
    The voltage comes from the UPS

    And what is the accuracy of the measurement?
  • #3 15212340
    retrofood
    VIP Meritorious for electroda.pl  
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    barytek wrote:
    This topic has already been discussed, but in 2013 and since then, a lot has changed in the Polish power grid.


    Report the topic of the energy supplier, maybe it is enough to regulate the voltage with taps on the transformer.
  • #4 15212395
    opornik7
    Electrician specialist  
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    retrofood wrote:
    Report about an energy supplier,

    But what is he supposed to report? That his voltage is normal?
  • #5 15212465
    CYRUS2
    Level 43  
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    For something to be damaged, the voltage must exceed 270V AC.

    In terms of equipment damage, the standard does not guarantee safety.
    There is no record that 253V is a limit that cannot be exceeded even for a time, e.g. 0.1sec.
    253V is just the average of the measurements over time.
    If the voltage in the network exceeds 350V for 0.1 sec, this average will be approx

    Near the transformer, the voltage is probably overestimated so that at the end of the line there is approx
    In such a situation, I would advise to protect valuable receivers - against the effects such as the voltage "jumps higher". There are no protections against the voltages of 300V-400V in the installation.
  • #6 15212666
    Anonymous
    Anonymous  
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  • #7 15212777
    barytek
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    The installation is three-phase.
  • #8 15213163
    retrofood
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    opornik7 wrote:
    retrofood wrote:
    Report about an energy supplier,

    But what is he supposed to report? That his voltage is normal?


    That he suspects the tension goes beyond the standard.

    He does not report to the prosecutor either committing by someone a crime, but suspicion of committing . The consumer is not authorized to judge whether the voltage is normal or not. It is up to the experts to investigate it.
  • #9 15213384
    jharlan
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    Małolepszym wrote:
    Is it three-phase? Significantly inflated voltages are sometimes caused by a stuck-badly contacting zero.

    barytek wrote:
    The installation is three-phase.

    CYRUS2 wrote:
    For something to be damaged, the voltage must exceed 270V AC.

    When N gets hot to the end it will be 400V ? 10%
  • #10 15213408
    retrofood
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    jharlan wrote:

    If N gets hot to the end it will be 400V ? 10%


    It will or it will not. It depends on the degree of load unbalance.
  • #11 15213529
    DJ ANNUS
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    barytek wrote:
    sometimes my voltage is usually from 237v to 248v, 244v most of the time


    At my previous location there was 250V nonstop and it is still used today.
    And it was the 3rd pole from a large 400kVA transformer. in the countryside.
    The upside is that the mower on the extension cord still had a lot of power and I could do something for myself, e.g. aluminum rims or other delicacies.
    I have not noticed any heat damage to the equipment.
    But the voltage was stable at 250V.
  • #12 15213540
    jharlan
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    retrofood wrote:
    jharlan wrote:

    If N gets hot to the end it will be 400V ? 10%


    It will or it will not. It depends on the degree of load unbalance.

    Rather, it will be closer to 400 than 270.
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  • #13 15213566
    retrofood
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    jharlan wrote:
    retrofood wrote:
    jharlan wrote:

    When N gets hot to the end it will be 400V ? 10%


    It will or it will not. It depends on the degree of load unbalance.

    Rather, it will be closer to 400 than 270.


    Rather not necessarily.
  • #14 15213572
    BILGO
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    barytek wrote:
    There was a small thunderstorm at the end of November. Just before the storm, the voltage exceeded 250V

    Quite normal, the load on the network dropped quickly as people disconnected their loads before the storm and the voltage had to increase as a result ;)
    barytek wrote:
    When it started to rain, the voltage dropped very quickly by over 15V

    People in the area said the thunderstorm was gone, so they turned on most of the receivers that were operating before the storm came. ;)
    barytek wrote:
    Most of the time, 244V

    Normal.
    barytek wrote:
    Do I alone have such high voltage fluctuations? The voltage comes from the UPS

    The one closest to the transformer is the worst ;) In general, there are voltage fluctuations in the network, it cannot be avoided ...
  • #15 15213590
    jharlan
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    BILGO wrote:
    barytek wrote:
    There was a small thunderstorm at the end of November. Just before the storm, the voltage exceeded 250V

    Quite normal, the load on the network dropped quickly as people disconnected their loads before the storm and the voltage had to increase as a result ;)
    barytek wrote:
    When it started to rain, the voltage dropped very quickly by over 15V

    People in the area said the thunderstorm was gone, so they turned on most of the receivers that were operating before the storm came. ;)
    barytek wrote:
    Most of the time, 244V

    Normal.
    barytek wrote:
    Do I alone have such high voltage fluctuations? The voltage comes from the UPS

    The one closest to the transformer is the worst ;) In general, there are voltage fluctuations in the network, it cannot be avoided ...

    This is a logical explanation, but let N check it.
    There is also the question of the accuracy of the measurement.
  • #16 15213625
    BILGO
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    jharlan wrote:
    but let N check.

    An overhaul of the installation won't hurt. Knowing life, an electrician recently saw the installation as he made it ... this is the reality in the construction of single-family houses ;)
  • #17 15213827
    tom_bart1
    Level 14  
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    BILGO wrote:

    Quite normal, the load on the network dropped quickly as people disconnected their loads before the storm and the voltage had to increase as a result

    It is more likely to disconnect another MV line supplied from the same substation, or to disconnect one of the HV lines supplying this substation. ARN automation works with a certain delay.
  • #18 15214622
    CYRUS2
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    retrofood wrote:
    It will or it will not. It depends on the degree of load unbalance.

    PEN burnout within the network is the asymmetry of many receivers - this is averaged.
    The PEN break for a single object is worst. Because then the asymmetry is not averaged, you can expect 400V on the receiver.
    Varistors in equipment cause chain reactions.
    The varistor gets a short and gives clean phase to another receiver.
  • #19 15215615
    bizon_126
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    I would like to have such a supply voltage, because Saturday evening at my place is 190 V, sometimes not even all of it
    There was a conversation with the energy industry but I didn't hear anything concrete - they have it in ...
  • #20 15216026
    opornik7
    Electrician specialist  
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    bizon_126 wrote:
    I would like to have such a supply voltage, because Saturday evening at my place is 190 V, sometimes not even all of it
    There was a conversation with the energy industry but I didn't hear anything concrete - they have it in ...

    Advice for the future, do not talk, just write a letter with a request to provide energy with parameters in accordance with the contract.
  • #21 15216048
    DJ ANNUS
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    opornik7 wrote:
    Advice for the future, do not talk, just write a letter with a request to provide energy with parameters in accordance with the contract.


    I reported it, situation as above. they arrived, measured at the pole around 11.00 when the consumption was the lowest and they went, apparently it was normal.
    You can dream that they will come for the measurement at 7-8 am or around 5-20 pm.

    But still, at 15kW, I have a 199V phase in the hourly interval as above.
    At 32A it drops to 160V. :D
    And each compressor included causes such a load.
  • #22 15216179
    Darom
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    Apply for an analyzer. They will have a 24/7 cross-section regarding stresses and loads.

    kisses
    - GIFT-
  • #23 15216196
    bizon_126
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    They came exactly at noon with the meter at the meter and said that it was ok and they did not see the problem, sat down and went
    Let someone prove himself and make a measurement Saturday evening as in every other house, a 2.0 kw heater heats the water often densely to the oven and not to mention the street light
    When I once welded a sheet metal, it started to weld well after 23 - everyone is asleep and when the street ones turned off it was quite a fairy tale
  • #24 15216271
    zbich70
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    bizon_126 wrote:
    Let someone prove himself and make a measurement Saturday evening as in every other house, a 2.0 kw heater heats the water often densely to the oven and not to mention the street light

    But who is to prove himself? Forum readers are to prove themselves - come to Olkusz and install a recorder?
    Can he write a letter to the supplier for you?
  • #25 15216284
    bizon_126
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    The management is probably Będzin, I don't even know exactly
    A neighbor wrote letters and they were twice during office hours, i.e. at noon, and they found no groundless accusations
  • #26 15216319
    zbich70
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    bizon_126 wrote:
    A neighbor wrote letters and they were twice during office hours, i.e. at noon, and they found no groundless accusations

    Then write a letter stating that the problem only occurs in the evenings on public holidays.
    The energy emergency works 24/7 so it shouldn't be a problem.

    But if you write as carelessly as here on the forum, be aware that you will be treated as carelessly.
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  • #27 15216341
    bizon_126
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    I work from 7 am to 5 pm so I do not have much time for such dealing with officials
  • #28 15216388
    zbich70
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    bizon_126 wrote:
    I work from 7 am to 5 pm so I do not have much time for such dealing with officials

    So what? You can't do it until 5 p.m. because you are working. Not after 5 pm either, because then you rest.
    So, in your letter to the supplier, state what hours you are satisfied with.
  • #29 15216445
    bizon_126
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    After 5 p.m. I have other duties
    The truth is that it would be best to throw the transformer closer or, if such an option is an option, put a strand through the village instead of 30-year-old lines
    I have a kilometer to the transformer, maybe not all, and I do not have a tip
  • #30 15216504
    DJ ANNUS
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    bizon_126 wrote:
    After 5 p.m. I have other responsibilities
    The truth is that it would be best to throw the transformer closer or, if such an option is an option, put a strand through the village instead of 30-year-old lines
    I have a kilometer to the transformer, maybe not all, and I do not have a tip


    Buddy, if you want to do something, e.g. an autotransformer on some pole, then you need to talk to someone who can do something.

    Or, with the neighbors, make a harassing and polished attack on the PGE hotline or whatever you have there, because if they have a report, they must react.

    This was also the case with street lighting, I called 7 or 10 times and they came and finally they discovered that one lamp short-circuited after some time and extinguishes the entire street.
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Topic summary

✨ The discussion revolves around high voltage fluctuations in the Polish power grid, particularly since 2013. A user reports experiencing voltage levels between 237V and 248V, with spikes exceeding 250V during storms, prompting the purchase of a UPS for stabilization. Participants highlight that permissible voltage deviations are +/- 10% (207V to 253V) and suggest reporting issues to the energy supplier, as voltage regulation may be possible. Concerns about equipment safety are raised, noting that voltages exceeding 270V can cause damage. The conversation also touches on the impact of load imbalances and the importance of accurate measurements. Users share personal experiences with voltage stability and fluctuations, emphasizing the need for proper documentation and communication with energy providers to address undervoltage issues.
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FAQ

TL;DR: Polish low-voltage networks must hold 230 V ± 10 % (207-253 V) [Elektroda, jharlan, post #15212297]; “voltage up to 253 V is still 'normal'” [Elektroda, jharlan, post #15212297] Brief spikes above 250 V near transformers are common and usually harmless if below 270 V [Elektroda, CYRUS2, post #15212465] Why it matters: knowing the limits helps you decide when to complain—or when to install protection.

Quick facts • Polish/EU tolerance: 230 V ± 10 %, 95 % of 10-min averages (EN 50160) • Damage risk climbs sharply above 270 V AC [Elektroda, CYRUS2, post #15212465] • Neutral break can expose outlets to ~400 V in three-phase homes [Elektroda, CYRUS2, post #15214622] • Utility must investigate written quality complaints within 14 days (Energy Law Art. 7-9, 2023) • A portable power analyzer rental costs ~120 PLN/week (Energo-Control, 2024)

Quick Facts

• Polish/EU tolerance: 230 V ± 10 %, 95 % of 10-min averages (EN 50160) • Damage risk climbs sharply above 270 V AC [Elektroda, CYRUS2, post #15212465] • Neutral break can expose outlets to ~400 V in three-phase homes [Elektroda, CYRUS2, post #15214622] • Utility must investigate written quality complaints within 14 days (Energy Law Art. 7-9, 2023) • A portable power analyzer rental costs ~120 PLN/week (Energo-Control, 2024)

What voltage range is legally acceptable in Polish household sockets?

EN 50160 and national rules allow 230 V ± 10 %, so any 10-minute average between 207 V and 253 V meets the standard [EN 50160][Elektroda, jharlan, post #15212297]

Is 244–250 V harmful to my appliances?

Most devices tolerate up to 253 V continuously. Damage risk rises only above about 270 V AC [Elektroda, CYRUS2, post #15212465] Switch-mode supplies and LED bulbs are rated to 265 V nominal (datasheets, 2024).

Why does voltage climb before a thunderstorm and drop when rain starts?

Many users disconnect loads before lightning, reducing current draw and letting the feeder voltage float higher; once rain calms fears, loads return and voltage falls [Elektroda, BILGO, post #15213572]

How accurate is a UPS display for measuring mains voltage?

UPS LCDs are typically ±5 V. Use a calibrated multimeter or a class 0.5 recorder for complaints. Inaccurate readings weaken claims [Elektroda, jharlan, post #15212297]

How can I formally complain about over- or undervoltage?

Write (not call) your supplier, request compliance with EN 50160, and ask for a 7-day analyzer. They must respond and share the report [Energy Law Art. 7-9, 2023]. Forum users confirmed written requests get recorders installed [Elektroda, tronics, post #15216979]

What if technicians test only at noon and miss the problem?

State the exact hours of trouble in your letter and insist on 24-hour recording. Emergency crews operate 24/7, so evening checks are feasible [Elektroda, zbich70, post #15216319]

Can a local autotransformer fix chronic low voltage?

Yes. A 5 kVA step-up autotransformer can add 10-15 % and costs ~800 PLN. It protects one house but doesn’t solve grid issues [Elektroda, DJ ANNUS, post #15216504]

How do I protect sensitive gear from extreme surges?

  1. Install Type 3 surge arresters in power strips.
  2. Add an AVR or line-interactive UPS with ±8 % regulation.
  3. For workshops, fit an automatic tap-changing stabilizer (±20 %) rated for peak load. This covers 300-400 V spikes from neutral loss edge cases [Elektroda, CYRUS2, post #15214622]

Could low voltage shorten appliance life?

Yes. Motors draw higher current, overheating by ~8 % for every 10 % undervoltage [IEEE Std 141-2010]. Persistent 190 V reports justify action [Elektroda, bizon_126, post #15215615]

What’s an easy three-step procedure to file a voltage complaint?

  1. Record dates, times, and measured voltages for one week.
  2. Send a registered letter with data, citing EN 50160 and contract clause.
  3. Request a portable analyzer within 14 days and ask for written results.

Is there a cost if the analyzer shows voltage within limits?

Suppliers may bill testing costs (approx. 300 PLN) if parameters are compliant; they waive the fee when limits are breached (PGE T&C §12, 2024).

Can repeated 350 V spikes average out as ‘within 253 V’?

Short 0.1 s spikes barely affect 10-minute averages, so EN 50160 may still be met [Elektroda, CYRUS2, post #15212465] That’s why surge protection, not just standards, matters.

What’s the cheapest temporary fix for evening sags to 190 V?

A 2 kW ferroresonant constant-voltage transformer (~350 PLN used) can hold 220–230 V output down to 160 V input. It hums and wastes ~50 W standby, but saves equipment during peak demand.
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