Hi. Technical parameters of the connection: Power 18 kW, protection 32A. The length of the WLZ is approximately 22 m. Power-hungry devices - 1-phase heat pump, thermal power 7 kW (electric power max 3.5 on one phase, plus graduated heaters 3-6 kW on the second phase), 7.5 kW induction divided...

YAKY 4x25mm² meets your needs.

And don`t even think twice about it. Almost all power industry runs on aluminum cables.

The calculated voltage drop from the point of connection to the last receiver in the installation cannot exceed 3%. In addition, you should check the conditions for the effectiveness of protection against electric shock if the power supply is in the TN system, and, of course, check the load capacity of this cable.

What is the maximum load capacity of a 4x10 Cu cable? So safe that it won`t flood the insulation. Will it pull with 22 kW?

Tables of long-term, permissible load capacity of wires (cables, too, in terms of cross-section of wires) are published. You just need to find one that will suit the way the cable is laid, i.e. the environmental conditions. At the same time, we must not forget about the principle of chain strength. A chain is only as strong as its weakest link. That is, we select the table for the least favorable conditions on the route, even if they occur only at a length of several dozen centimeters.

Does the presence of PV and current flow in both directions influence the selection of the diameter of the WLZ cables?

Of course. You select the cross-section for greater flow. If you intend to send more to the grid than you have in your energy supply contract, you select the wlz cross-section for sending to the grid, not for receiving from the grid. But I don`t think you should decide on a higher PV power than 18 kW, and that`s how much your wlz is selected. Added after 10 [minutes]: 22 kW exceeds the permissible current of Cu 4x10mm². In addition, the current flowing is greater than the protection value (32A), and after some time the protection will turn off the circuit.

Thanks. I don`t expect the PV to be higher than the connection power With these 22 kW, I was thinking more about the future and, if necessary, increasing the protection to 40A. At 22 kW of power we have about 7.33 kW per phase, which gives a current of practically 32A per phase. A 10mm2 wire won`t withstand 32A for a long time?

It won`t last under certain conditions, so I wouldn`t sign it. But the proposed AL 25 fulfills your dreams; will withstand and 30 kW.

[Solved] Cable cross-section for WLZ for 18kW, 32A, heat pump and induction - copper or aluminum?

R1990 12183 10

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#1 19454582 28 May 2021 07:53

R1990 R1990

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Post #1
19454582 28 May 2021 07:53

Hi.
Technical parameters of the connection:
Power 18 kW, protection 32A. The length of the WLZ is approximately 22 m. Power-hungry devices - 1-phase heat pump, thermal power 7 kW (electric power max 3.5 on one phase, plus graduated heaters 3-6 kW on the second phase), 7.5 kW induction divided into 2 phases, probably some car charging in the future electric charger 3f 11 kW from the power connector in the garage. Some say 4x10, others 4x16 (for the future), and some say about aluminum, and this is where I started to consider it, because copper prices are a failure. Aluminum is probably 4x25, so I would be 600 hundred points ahead of Cu.
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#2 19454610 28 May 2021 08:35

stonefree stonefree

Level 27

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Post #2
19454610 28 May 2021 08:35

The calculated voltage drop from the point of connection to the last receiver in the installation cannot exceed 3%. In addition, you should check the conditions for the effectiveness of protection against electric shock if the power supply is in the TN system, and, of course, check the load capacity of this cable.
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#3 19454627 28 May 2021 09:01

tyqva tyqva

Level 35

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Post #3
19454627 28 May 2021 09:01

R1990 wrote:
...Aluminum is probably 4x25 so I would be 600 hundred points ahead of Cu.

YAKY 4x25mm² meets your needs.
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#4 19454731 28 May 2021 10:24

retrofood retrofood

VIP Meritorious for electroda.pl

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Post #4
19454731 28 May 2021 10:24

R1990 wrote:
Aluminum is probably 4x25, so I would be 600 hundred points ahead of Cu.

And don`t even think twice about it. Almost all power industry runs on aluminum cables.
#5 19456878 29 May 2021 21:36

R1990 R1990

Level 9

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Post #5
19456878 29 May 2021 21:36

What is the maximum load capacity of a 4x10 Cu cable? So safe that it won`t flood the insulation. Will it pull with 22 kW?
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#6 19456913 29 May 2021 21:58

retrofood retrofood

VIP Meritorious for electroda.pl

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Post #6
19456913 29 May 2021 21:58

R1990 wrote:
What is the maximum load capacity of a 4x10 Cu cable? So safe that it won`t flood the insulation. Will it pull with 22 kW?

Tables of long-term, permissible load capacity of wires (cables, too, in terms of cross-section of wires) are published. You just need to find one that will suit the way the cable is laid, i.e. the environmental conditions. At the same time, we must not forget about the principle of chain strength. A chain is only as strong as its weakest link. That is, we select the table for the least favorable conditions on the route, even if they occur only at a length of several dozen centimeters.
#7 19458926 31 May 2021 09:54

R1990 R1990

Level 9

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Post #7
19458926 31 May 2021 09:54

Does the presence of PV and current flow in both directions influence the selection of the diameter of the WLZ cables?
#8 19458976 31 May 2021 10:43

tyqva tyqva

Level 35

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Post #8
19458976 31 May 2021 10:43

R1990 wrote:
Does the presence of PV and current flow in both directions influence the selection of the diameter of the WLZ cables?

Of course.
You select the cross-section for greater flow. If you intend to send more to the grid than you have in your energy supply contract, you select the wlz cross-section for sending to the grid, not for receiving from the grid.
But I don`t think you should decide on a higher PV power than 18 kW, and that`s how much your wlz is selected.

Added after 10 [minutes]:

R1990 wrote:
What is the maximum load capacity of a 4x10 Cu cable? So safe that it won`t flood the insulation. Will it pull with 22 kW?

22 kW exceeds the permissible current of Cu 4x10mm². In addition, the current flowing is greater than the protection value (32A), and after some time the protection will turn off the circuit.
#9 19459003 31 May 2021 10:51

R1990 R1990

Level 9

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Post #9
19459003 31 May 2021 10:51

tyqva wrote:

R1990 wrote:
Does the presence of PV and current flow in both directions influence the selection of the diameter of the WLZ cables?

Of course.
You select the cross-section for greater flow. If you intend to send more to the grid than you have in your energy supply contract, you select the wlz cross-section for sending to the grid, not for receiving from the grid.
But I don`t think you should decide on a higher PV power than 18 kW, and that`s how much your wlz is selected.

Added after 10 [minutes]:

R1990 wrote:
What is the maximum load capacity of a 4x10 Cu cable? So safe that it won`t flood the insulation. Will it pull with 22 kW?

22 kW exceeds the permissible current of Cu 4x10mm². In addition, the current flowing is greater than the protection value (32A), and after some time the protection will turn off the circuit.

Thanks.
I don`t expect the PV to be higher than the connection power
With these 22 kW, I was thinking more about the future and, if necessary, increasing the protection to 40A.
At 22 kW of power we have about 7.33 kW per phase, which gives a current of practically 32A per phase. A 10mm2 wire won`t withstand 32A for a long time?
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#10 19459154 31 May 2021 12:41

tyqva tyqva

Level 35

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Post #10
19459154 31 May 2021 12:41

R1990 wrote:
...A 10mm2 wire won`t withstand 32A for a long time?

It won`t last under certain conditions, so I wouldn`t sign it.
But the proposed AL 25 fulfills your dreams; will withstand and 30 kW.
#11 19757320 11 Dec 2021 15:52

R1990 R1990

Level 9

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Post #11
19757320 11 Dec 2021 15:52

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Topic summary

The discussion revolves around selecting the appropriate cable cross-section for a WLZ (main power supply line) to support an 18 kW load with a 32A protection, considering future expansions such as a heat pump and induction cooktop. Users suggest that a 4x25 mm² aluminum cable would meet the requirements, as it can handle higher loads and is more cost-effective than copper. Concerns about voltage drop, load capacity, and the impact of photovoltaic (PV) systems on cable selection are also addressed. The consensus is that a 4x10 mm² copper cable would not suffice for the anticipated load, especially if future upgrades to 40A protection are considered.
Summary generated by the language model.