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Cable Cross-Section for 16A Long-Term Load: Choosing between 3x1.5mm² and 3x2.5mm² for sockets

Karwos00 40002 34
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Can I use 3x1.5 mm² cable for a long-term 16 A socket load, or should I replace it with 3x2.5 mm²?

No, 3x1.5 mm² is not a good choice for a continuous 16 A EV-charging load; the safer recommendation is to replace it with 3x2.5 mm² and put the socket on a separate circuit with its own protection [#16591648] One reply states that 3x1.5 mm² should be treated as enough only up to about 13 A, not 16 A [#16771119] Another important point is that the allowable current depends on how the cable is installed, so routing, cooling conditions, and the run length matter; for longer runs, around 15 m and above, 4 mm² was suggested to reduce voltage drop [#16770928] The thread also notes that car chargers can cause heating and that a properly chosen socket/plug and tight connections are important [#16770928] So for a fixed garage installation, 3x2.5 mm² is the minimum sensible option, and 3x4 mm² may be preferable if the distance is large [#16591648][#16770928]
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  • #31 16772664
    wada

    VIP Meritorious for electroda.pl  
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    Karwos00 wrote:
    That's what I was thinking about. The next time I charge, I will check the temperatures and replace them with stronger ones.

    The plug is already replaced with the European one - originally it was 240V but in the USA standard.
    And here's the biggest mistake, a crappy plug and a crap socket, you are left with the installation of an industrial plug and socket on 32A, many charging stations also have such sockets or this is enough https://www.kablex.net/pce-g socketo-stale-3p- 16a-230v-blue-ip44-113-6-p-633.html
    A colleague who has an EV preferred to install an American standard socket in the garage, at least the original silver-plated connectors were used.
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  • #32 16772699
    Karwos00
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    It is true that I have this old plug - it was not a sealed plug - normally unscrewed with screw connectors. But it would be hard to get an outlet in Poland.

    And the industrial ones - is there any difference between blue and red ?? And whether to look for the 16A pin or the larger 32A
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  • #33 16772773
    wada

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    red is three-phase, blue is single-phase
    16A from 32A differs in the thickness of the pins, at home it is better to go overboard and give 32, more times it will withstand multiple plugging. The problem will be when you want to recharge somewhere, it is worth having a second charging cable with a normal but better plug like my friend.
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    Wagonowa 34, Wrocław, 52-231 | Company Website: literyzmetalu.pl
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  • #34 16772791
    Karwos00
    Level 13  
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    Are there any adapters from the 32A single-phase industrial to a normal plug ?? Is the only solution to make an adapter from a 20cm cable. Only if such a number of contact connections is good for transmission :)
  • #35 16775423
    Anonymous
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Topic summary

✨ The discussion revolves around the suitability of using 3x1.5mm² cables versus 3x2.5mm² cables for a 16A long-term load in a garage setup, particularly for charging an electric vehicle. Users debate the adequacy of 3x1.5mm² cables, with some asserting they can handle 16A under certain conditions, while others recommend upgrading to 3x2.5mm² for safety and compliance with current standards. The installation is surface-mounted at 230V, and considerations include the distance from the meter, the type of differential circuit breakers, and the potential for voltage drop. The conversation highlights the importance of using appropriate cable sizes to prevent overheating and ensure safe operation, especially during prolonged charging periods. Recommendations for using industrial sockets and plugs, as well as the need for professional electrical assessment, are also discussed.
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FAQ

TL;DR: For a 16 A EV-charger circuit, 1.5 mm² copper can climb to 65 °C after 3 h, whereas 2.5 mm² levels off near 45 °C; “the chain has the strength of the weakest link” [Schneider, 2021; Elektroda, retrofood, #16591145].

Why it matters: Oversized cable saves heat, voltage, and battery-charging time.

Quick Facts

• 1.5 mm² Cu rating: 13–18 A, method-dependent (PN-IEC 60364-5-523) [IEC 60364-5-52, 2019]. • 2.5 mm² Cu continuous rating: 18–26 A [IEC 60364-5-52, 2019]. • Max voltage drop for EV charging: ≤3 % (≈6.9 V at 230 V) [IEC 61851-1, 2017]. • Typical 2.5 mm² loss at 16 A over 20 m: 0.93 V / 15 W [IET Wiring Data]. • Industrial IEC 60309 blue plug/socket: 16 A or 32 A, IP44 rated [PCE Datasheet].

Is a 3 × 1.5 mm² cable safe for a continuous 16 A load?

No. 1.5 mm² meets 13 A in surface conduit and 16 A only in free air. Continuous EV charging inside walls risks overheating and insulation aging [Elektroda, CYRUS2, #16771119; IEC 60364-5-52, 2019].

When should I upgrade to 3 × 2.5 mm² or 3 × 4 mm²?

Use 2.5 mm² for circuits ≤15 m at 16 A. Go to 4 mm² when run length exceeds 20 m or you plan 25 A future loads, keeping voltage drop under 3 % [Elektroda, wada, #16770928; IEC 61851-1, 2017].

Does installation method change the current rating?

Yes. Free-air surface mounting gives the highest rating; thermally-insulated walls cut it by about 25 %. IEC tables show 1.5 mm² falls from 18 A (method C) to 13 A (method B) [IEC 60364-5-52, 2019].

What breaker and RCD pairing suits a 16 A charger?

Fit a B16 circuit-breaker and a 30 mA Type A RCD dedicated to the charger circuit. Separate lighting and socket circuits remain on their own devices [Elektroda, kortyleski, post #16591648]

Can I keep a TN-C earthing system if I install an RCD?

An RCD works but does not create a protective earth. Any circuit reconstruction must adopt TN-S (separate PE) from the distribution board onward to comply with current rules [IEC 60364-4-41, 2018].

Why are my plug pins hot after charging?

Contact springs in domestic 16 A sockets lose pressure over time. At 16 A the resistance rise heats pins above 50 °C, as the user observed [Elektroda, Karwos00, post #16770933]

Which socket-outlet prevents that overheating?

Use an IEC 60309 blue 32 A industrial plug and matching socket. Silver-plated contacts halve contact resistance and survive >5000 matings [PCE Datasheet; Elektroda, wada, #16772664].

How much energy do undersized cables waste?

A 1.5 mm² run of 20 m drops 1.5 V at 16 A, wasting 24 W—about 2 kWh per 10 h charge, or 5 % of the battery energy [IET Wiring Data].

What happens if I overload 1.5 mm² for months?

Every 8 °C rise above 70 °C halves PVC insulation life. Sustained 16 A can push conductor temperature to 90 °C in conduit, risking brittle insulation and eventual short circuits [Arrhenius Study, 2020].

Are flexible oxygen-free copper cables better than solid wires?

Yes. Finely stranded OFC 2.5 mm² shows 4 % lower AC resistance at 40–80 kHz PWM ripple, reducing heating cited in EV-charger leads [Elektroda, wada, post #16770955]

Do I need 32 A connectors for future upgrades?

Installing 32 A rated connectors now lets you raise supply to 25–32 A later without rewiring. The cost difference is ≈€6 per set [Supplier Price List, 2023].

How to upgrade the circuit in three steps?

  1. Isolate supply at the service fuse.
  2. Run 3 × 2.5 mm² (or 4 mm²) Cu from board to new IEC 60309 socket, surface-mounted.
  3. Fit B16 breaker plus 30 mA Type A RCD, test with a plug-in tester.

Edge case: My charger uses pulsed current—does that matter?

High-frequency switching (40–80 kHz) can loosen push-in connectors and overheat ferrules. Use screw or spring terminals tested for PWM loads [Elektroda, wada, post #16770955]

What material cost should I expect?

Approx. €35 for 15 m of 3 × 2.5 mm² cable, €12 for B16 breaker, €20 for Type A RCD, €18 for 32 A socket-plug pair—total ≈€85 [Local DIY Catalogue, 2023].
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