Electric cable cross-section

Hello everyone,

the electrical system of our house has just been completely renewed. Cable cross-section 1 square. Now another "expert" told me that I should have taken at least 1.5 so that the fuses stay in when I switch on several consumers. Now I am uncertain and would like your opinion.

Regards Karsten

Hello everyone,

the electrical system of our house has just been completely renewed. Cable cross-section 1 square. Now another "expert" told me that I should have taken at least 1.5 so that the fuses stay in place when I turn on several consumers. Now I am insecure and would like to have your opinion.

Regards Karsten

Hello

As far as I know, 1² is definitely too little for a normal house installation. Usually 1.5² is used. The latter must be protected with a 16A fuse, with 1² the fuse protection must be 10A (B10A circuit breaker in the fuse box).
The stove is usually connected with 2.5².

Please take a look in your fuse box - if there are 16A circuit breakers in there, then that is very bad!
Protecting 1² with 16A can lead to overheating and thus a fire!

Otherwise, it also depends on how the cables are laid.
Are they simply "normally" laid under plaster in the wall, or was a conduit used?
Which type of cable was used? "Normal" NYM cable? (Printed on the cable sheath - if you still have some remnants lying around somewhere)
There are cables that have a higher current carrying capacity - but also a higher price...

By the way - I am not sure if 1² is even approved for house installation...

If in doubt, hire a professional / expert who can look at the whole thing on site and not just guess blindly over the internet...

Regards
Micha

Hello and thank you very much for the detailed answers.

I can give the all-clear. I spoke with the electrician who assured me that everything was installed with 1.5 q. 16A fuses are also in place.
My "expert" had seen an old dead cable with probably 1.0 q and thought—because it still looked very good—that it was a new line.

Thanks again for the answers, I feel good again now and have learned something new.

Best regards Karsten

Hello everyone,

I’m trying to shed a little light on the matter. 1mm² has not been available for a long time, not even as a flat cable [Stegleitung]. Basically, the cable cross-section is designed according to the upstream fuse:

So you want to be able to draw 16A from a socket. By the way, that is the maximum current for conventional [Schukosteckdosen]. To ensure 16A, I have to calculate the cable cross-section based on the length of the cable (loop impedance). So a 3x1.5mm² cable can be laid a maximum of 17m if it is to be loaded with 16A. Either you take a smaller fuse, for example 10A, then you get about 23m, but then you only have a max of 10A at the socket. The next option is to increase the cross-section to 2.5mm². This then allows a maximum length of 25m.

So you cannot generally say that 1.5mm² is sufficient. That it is the minimum cable cross-section for flush-mounted house installation becomes clear when the resourceful DIYer tries to buy [NYM Leitung] at the hardware store.

That the stove should therefore be connected with 2.5mm², since usually a 20A fuse is also recommended by the manufacturer, now becomes clear. But here too, be careful with the cable length. Also note here: new ovens are usually delivered with a normal [Schukostecker]. In this case, only the oven should be connected to this fuse (socket). The same applies to dishwashers.

And please remember, all circuits that lie within the non-professional area must have [FI] protection since mid-2007. This also applies to DIYers!

It is best to have a registered craftsman take another look at the whole matter.

This is only meant to be a very brief and rough overview! The matter is much more complex.

Regards
JonnY

Hello, I am digging up this old thread because it comes up high on Google when searching for cable cross-section.

Can someone explain JonnY's calculation with the maximum length of 25m at 16A and 2.5mm² cross-section? I am not an expert, but I come to the following result with 50m cable length:

Given:
Cross-section 2.5mm²
50m cable length i.e. 100m conductor length
230V, 16A i.e. 3680W

With that, I come to (Cu, 20°C):
Line resistance: 0.71 Ohm
Voltage drop: 10.85 Volts
Power loss: 165.47 Watts
and thus an efficiency of 95.28%.

I have heard from a "professional" that everything over 95% would be okay. Is this information wrong?

Would be grateful for clarification or a calculation method!