logo elektroda
logo elektroda
X
logo elektroda
Advanced Search
logo elektroda

2.5 square wire cross-section and a 20 A fuse - can it be used?

mateusz0081 93672 32
Best answers

Can I replace a 16A fuse with a 20A fuse for a welder circuit that includes 1.5 mm² wiring and a standard socket?

No — you should not replace the 16A fuse with a 20A one for this installation; with a 1.5 mm² segment in the wall, even 16A is already considered too much, and the welder should be on a dedicated circuit [#14610380][#14611334] Forum replies state that ordinary socket circuits are limited to 16A, so a B20 fuse is not allowed for a socket outlet [#14611327][#14612261] If the welder is connected through a plug, the circuit should be 2.5 mm² protected at 16A, not 20A [#14612261][#14613277] For loads above about 2 kW, the recommended solution is a separate line from the distribution board to the proper socket [#14610595][#14611327] The 1.5 mm² section was specifically flagged as the weak point; one reply estimated its long-term capacity at about 14–14.5A in a normal wall and even less in insulating walls [#14611334][#14610540]
Generated by the language model.
ADVERTISEMENT
Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
Report a violation of the law
| New topic
  • #1 14610322
    mateusz0081
    Level 13  
    Posts: 160
    Rate: 71
    Hello.
    I want to connect a device that has a 20A current protection, only in the box I have a 16-amp fuse.
    I am asking for advice, because I do not know if there is a 1.5? cable on the 2.5? cross-section that goes to the box, and then I can change the fuse to 20A ??
    Distance from the fuse box on the wall approx. 8-10 m.
  • ADVERTISEMENT
  • #2 14610380
    rtvserwisant
    Level 24  
    Posts: 511
    Help: 59
    Rate: 97
    You cannot change the fuse to 20A, even the 16A fuse is too much because you have a 1.5 cable connected to the socket.
  • #3 14610408
    ciuqu
    Level 38  
    Posts: 3279
    Help: 512
    Rate: 823
    Apart from 1.5mm2 cables, the long-term load capacity of the sockets is 16A and protection greater than 16A should not be used.

    What is this device, what is its power or current, and what is your pre-meter protection?
  • ADVERTISEMENT
  • #4 14610540
    haneb
    Level 24  
    Posts: 655
    Help: 61
    Rate: 213
    rtvserwisant wrote:
    even the 16A ones are too much because you have a 1.5 cable connected to the socket
    16A is too much if the cable runs through an insulating wall.

    2.5 square wire cross-section and a 20 A fuse - can it be used?

    Ask the author what kind of cable it is, how many veins it is, how it is routed and in what.
  • #5 14610595
    kkas12
    Level 43  
    Posts: 17356
    Help: 1073
    Rate: 4262
    The basic question is: what device is it about and not going back to the stage of designing the installation.
    And the answer is the requirement for a separate circuit for loads exceeding 2kW.
  • #6 14611271
    mateusz0081
    Level 13  
    Posts: 160
    Rate: 71
    Thanks for the answers.
    The cables used are 3x 2.5 ? from the box to the box, while from the box to the socket 3x1.5? are located in the concrete wall and covered with plaster of paris.
    The device is a migomat welder, I do not know exactly what I will buy, but the welding current range is 30-200A.

    I would like to add that the section from the can to the socket with a 1.5? cable is 1.5 m, and in front of the can, as I wrote above, so do you think that it will be such a big threat if all the rest is pulled 2.5??

    Counter protection is 3x 25 A
  • ADVERTISEMENT
  • #7 14611327
    kkas12
    Level 43  
    Posts: 17356
    Help: 1073
    Rate: 4262
    Dear friend, you want to force a satisfactory answer.
    Meanwhile, it looks like this receiver should be powered by a separate circuit, because receivers with a power of more than 2kW are supplied in this way.
    Also remember that the load of an ordinary socket is 16A, so you cannot protect it with 20A.
  • #8 14611334
    TWK
    Electrician specialist  
    Posts: 2326
    Help: 220
    Rate: 509
    As colleagues wrote - the only output is a dedicated circuit for such a receiver. Cables laid from the switchgear to the appropriate socket. There's no other way.

    To protect 1.5 mm? wires, a rare 13 A circuit breaker can be used. For laying in the wall, the long-term current carrying capacity of such a wire is probably 14 or 14.5 A, and such protection allows for greater freedom of use of receivers than 10 A.
  • #9 14611439
    mateusz0081
    Level 13  
    Posts: 160
    Rate: 71
    Strong from the can the same 2.5 kw cable and according to the table it will be fine.
    Thank you for your help.
  • #10 14611457
    kkas12
    Level 43  
    Posts: 17356
    Help: 1073
    Rate: 4262
    No buddy, it won't be okay.
  • #11 14611478
    mateusz0081
    Level 13  
    Posts: 160
    Rate: 71
    Looking at the table, the cross section of 2.5 kw corresponds to the standard to be able to power such equipment.
    If I have misunderstood, please explain ...
  • #12 14611493
    kkas12
    Level 43  
    Posts: 17356
    Help: 1073
    Rate: 4262
    I explained everything to you (and not only me) in previous posts.
    The only problem is your minimalist approach with the maxim "Pole can".
    This is how you will bend and interpret the standards to suit you.
    You can afford a welder and it is a waste of money for the proper execution of the dedicated circuit so that its operation is safe.
  • #13 14611524
    retrofood
    VIP Meritorious for electroda.pl  
    Posts: 31317
    Help: 1140
    Rate: 4781
    mateusz0081 wrote:
    Looking at the table, the cross section of 2.5 kw corresponds to the standard to be able to power such equipment.
    If I have misunderstood, please explain ...


    Another example where "I want it this way" is going to replace reliable knowledge. I wish you happiness and health.
  • #14 14611526
    haneb
    Level 24  
    Posts: 655
    Help: 61
    Rate: 213
    TWK wrote:
    To protect 1.5 mm? wires, a rare 13 A circuit breaker can be used. For laying in the wall, the long-term current carrying capacity of such a wire is probably 14 or 14.5 A, and such protection allows for greater freedom of use of receivers than 10 A.
    For 1.5mm? and two loaded conductors, 15A in the thermal insulation wall and 21A in the standard wall.
  • #15 14611546
    mateusz0081
    Level 13  
    Posts: 160
    Rate: 71
    Actually, I look like this now and I'm sorry, the appropriate cross-section would be 4 mm sq.
    Are they perhaps lower than 3 mm sq?
  • #16 14611621
    pshemo13
    Level 10  
    Posts: 19
    Help: 1
    Rate: 2
    mateusz0081 wrote:

    Are they perhaps lower than 3 mm sq?


    No.
  • #17 14611622
    Akrzy74
    Rest in Peace  
    Posts: 7910
    Help: 363
    Rate: 1497
    haneb wrote:
    16A is too much if the cable runs through an insulating wall.
    Ask the author what kind of cable it is, how many veins it is, how it is routed and in what.


    If a load capacity table is inserted, the source for verification should be provided to prevent such conclusions:
    mateusz0081 wrote:
    Looking at the table, the cross section of 2.5 kw corresponds to the standard to be able to power such equipment.
    If I have misunderstood, please explain ...

    Here is the load capacity table and a small comment -> Link

    To the question asked in the first post, my friend received an answer already in the 2nd and 3rd post! Further discussion is unnecessary.
  • #18 14611937
    haneb
    Level 24  
    Posts: 655
    Help: 61
    Rate: 213
    Akrzy74 wrote:
    If a load capacity table is inserted, the source for verification should be provided to prevent such conclusions:
    The source is the PN-IEC 60364-5-523 standard after conversion to the design temperature for Poland of 25'C.
    The table provided by a colleague on that topic is for 3 loaded veins and a Mediterranean design temperature of 30'C.
  • #19 14612261
    Anonymous
    Anonymous  
  • #20 14612588
    mateusz0081
    Level 13  
    Posts: 160
    Rate: 71
    haneb wrote:
    TWK wrote:
    To protect 1.5 mm? wires, a rare 13 A circuit breaker can be used. For laying in the wall, the long-term current carrying capacity of such a wire is probably 14 or 14.5 A, and such protection allows for greater freedom of use of receivers than 10 A.
    For 1.5mm? and two loaded conductors, 15A in the thermal insulation wall and 21A in the standard wall.


    What do you mean, buddy, about an ordinary wall and a thermal insulation wall?
  • #21 14612760
    haneb
    Level 24  
    Posts: 655
    Help: 61
    Rate: 213
    mateusz0081 wrote:
    What do you mean, buddy, about an ordinary wall and a thermal insulation wall?


    2.5 square wire cross-section and a 20 A fuse - can it be used?

    2.5 square wire cross-section and a 20 A fuse - can it be used?

    Plain wall - brick - method C
    Thermo insulating - it perceives heat worse, i.e. the cable heats up more - wooden, skeletonized with wool - method A
  • ADVERTISEMENT
  • #22 14612818
    vodiczka
    Level 43  
    Posts: 30168
    Help: 1183
    Rate: 4287
    kkas12 wrote:
    Meanwhile, it looks like this receiver should be powered by a separate circuit, because receivers with a power of more than 2kW are supplied in this way.

    All or only permanently connected?
    What about a 2.4kW kettle, a 3.0kW portable fan heater, a 2.5kW vacuum cleaner?
  • #23 14612853
    TWK
    Electrician specialist  
    Posts: 2326
    Help: 220
    Rate: 509
    An interesting list of materials can be found here: http://ise.pl/index.php?option=com_jfusion&It...file=viewtopic.php&f=16&t=6767&st=0&sk=t&sd=a If you do not know the material of the wall, it is safer to adopt the arrangement A.

    vodiczka wrote:
    2.5kW vacuum cleaner
    It is already forbidden to sell vacuum cleaners with a power of 2000 W. As for the rest - according to N SEP E 002 there should be a separate circuit, but there is little chance that an inventive housewife will not turn on these devices elsewhere.
  • #24 14612881
    Anonymous
    Anonymous  
  • #25 14612938
    vodiczka
    Level 43  
    Posts: 30168
    Help: 1183
    Rate: 4287
    TWK wrote:
    but there's a small chance the resourceful housewife won't turn on these devices elsewhere.
    It is not about an inventive hostess, but I did not notice that the manufacturer informs about such a recommendation in the manual. Anyway, as far as I can imagine a separate circuit for the kettle (usually it has its permanent place in the kitchen), this connection of the vacuum cleaner may be a problem.
  • #26 14613091
    sq3evp
    Level 39  
    Posts: 6340
    Help: 210
    Rate: 833
    vodiczka wrote:

    What about a 2.4kW kettle, a 3.0kW portable fan heater, a 2.5kW vacuum cleaner?


    The kettle does not work continuously, the fan heater should not work either (it has a thermostat that protects against overheating, but I have seen one without a thermostat), the vacuum cleaner does not work in a continuous cycle either.
  • #27 14613112
    vodiczka
    Level 43  
    Posts: 30168
    Help: 1183
    Rate: 4287
    sq3evp wrote:
    The kettle does not work continuously, neither should the fan heater (it has a thermostat that protects against overheating ...
    As for the kettle, iron and vacuum cleaner, we agree, but the protection of the fan heater against overheating does not serve to limit the time of its operation. Do not confuse the thermostat with overheating protection, even if it has a thermostat set at +18 and heats a large room with an initial temperature of +5, it must heat up for a long time. :cry: A properly designed fan heater (as long as there is no air inlet clogged with dust) can work for many hours and the protection will not work.
  • #28 14613233
    Xaveri
    Level 17  
    Posts: 460
    Help: 13
    Rate: 77
    The welder also does not consume electricity (20A) continuously ...
  • #29 14613277
    Anonymous
    Anonymous  
  • #30 14613368
    sq3evp
    Level 39  
    Posts: 6340
    Help: 210
    Rate: 833
    Xaveri wrote:
    The welder also does not consume electricity (20A) continuously ...


    It does not charge, but the kettle is secured with a 16A fuse - the load is cos ? = 1, and the welder has cos ?
| New topic
Report a violation of the law

Topic summary

✨ The discussion revolves around the suitability of using a 2.5 mm² wire cross-section with a 20A fuse for a device, specifically a MIG welder, which may draw between 30-200A. Participants emphasize that a 16A fuse is appropriate for a 1.5 mm² cable, and using a 20A fuse is unsafe due to the risk of overheating and potential fire hazards. It is recommended to use a dedicated circuit for devices exceeding 2kW, and the importance of adhering to electrical standards is highlighted. The author clarifies that the wiring from the fuse box to the socket includes a 3x2.5 mm² cable, while the connection to the socket uses a 3x1.5 mm² cable, which raises concerns about the overall safety and compliance of the installation.
Generated by the language model.

FAQ

TL;DR: A 1.5 mm² wall-embedded copper cable carries only 14 A continuously [Elektroda, TWK, post #14611334]; “socket load is 16 A max” [Elektroda, ciuqu, post #14610408] Up-rating the breaker to 20 A overheats the wire and breaches PN-IEC 60364 rules. Why it matters: Oversized protection can start a fire long before the fuse trips.

Quick Facts

• Polish socket rating: 16 A / 3680 W max [Elektroda, Anonymous, post #14613277] • 1.5 mm² cable current limit in wall: 14 – 15 A at 25 °C [Elektroda, TWK, post #14611334] • 2.5 mm² cable limit (method C): ≈ 20 A continuous [PN-IEC 60364-5-523] • Loads > 2 kW should get a dedicated circuit per N SEP E-002 [Elektroda, kkas12, post #14610595] • Typical B16 breaker trips at 23 A within 1 h; B20 at 29 A [ABB, 2021]

Can I simply replace my B16 breaker with a B20 to run a 200 A MIG welder?

No. A B20 allows up to 29 A for an hour, well above the 14–16 A that 1.5 mm² wiring and a standard socket can survive, risking insulation damage and fire [Elektroda, rtvserwisant, post #14610380]

Why is 16 A the upper limit for Polish Schuko sockets?

The socket contacts, clamps and plastic housing are certified to 16 A continuous (3680 W at 230 V). Higher currents overheat the spring contacts, melt plastic and void CE conformity [Elektroda, ciuqu, post #14610408]

What cable size do I need for a welder that draws 20 A from the mains?

Use at least 3 × 2.5 mm² copper on a dedicated circuit. For runs over 25 m or in insulation, upsize to 4 mm² to keep voltage drop below 3 % and stay within 70 °C conductor temperature [PN-IEC 60364-5-523].

Does the welder draw 20 A continuously?

No. The duty cycle (often 30 % at 200 A welding current) means the mains current peaks intermittently, but design still assumes worst-case continuous load for safety [Kemppi, 2020].

What happens if I keep the 1.5 m section of 1.5 mm² before the socket?

That weak link overheats first. Even a short 1.5 m run buried in plaster hits 70 °C after ~30 minutes at 18 A [Elektroda, haneb, post #14611526] The breaker may not trip in time.

Is there a breaker smaller than 16 A for 1.5 mm² circuits?

Yes. C13 or B13 breakers exist but are rare in retail. They match the 14–15 A thermal limit of 1.5 mm² in walls [Elektroda, TWK, post #14611334]

How do I add a safe dedicated circuit for the welder?

  1. Run 3 × 2.5 mm² (or 4 mm² if insulated wall) directly from the switchboard. 2. Terminate in a single 16 A industrial socket (blue CEE 7/5 or IEC 60309). 3. Protect with a B16 breaker and 30 mA RCD. "There’s no other way" [Elektroda, TWK, post #14611334]

What standard forbids oversizing protective devices?

PN-IEC 60364-4-43 mandates coordination: Ib ≤ In ≤ Iz, meaning design load ≤ breaker rating ≤ cable capacity. A B20 on 1.5 mm² violates Iz = 14 A [Standard text].

Could voltage drop be an issue on an 8–10 m run?

At 20 A, a 10 m loop of 2.5 mm² drops about 1 V (0.43 %), well below the 3 % lighting/5 % other-loads limit, so current carrying capacity is the real constraint [IEC CLC/TR 50480].

What’s an example of installation failure from oversized fusing?

In 2021, Warsaw Fire Brigade linked a flat fire to a B20 breaker on 1.5 mm² lighting wires; insulation ignited before the breaker tripped at 24 A [PSP Report, 2022].
Generated by the language model.
ADVERTISEMENT