K
Karsten 24413 Jan 2012 00:58Hello everyone,
the electrical system in our house has just been completely renewed. Cable cross-section is 1 square millimeter (1.55 square inches). Now, another "expert" told me that I should have used at least 1.5 square millimeters (2.33 square inches) so that the fuses don’t trip when I use several appliances at the same time. Now I’m unsure and would appreciate your opinions.
Regards, Karsten
the electrical system in our house has just been completely renewed. Cable cross-section is 1 square millimeter (1.55 square inches). Now, another "expert" told me that I should have used at least 1.5 square millimeters (2.33 square inches) so that the fuses don’t trip when I use several appliances at the same time. Now I’m unsure and would appreciate your opinions.
Regards, Karsten
M
Micha&Dany13 Jan 2012 06:40Karsten 244 schrieb:
Hello everyone,
The electrical wiring in our house has just been completely renewed. Cable cross-section is 1 square millimeter. Another "expert" told me that I should have used at least 1.5 instead, so the circuit breakers don’t trip when multiple appliances are turned on. Now I’m unsure and would like to get your opinions.
Regards, KarstenHello,
As far as I know, 1 mm² is definitely too small for a standard house installation. Usually, 1.5 mm² is used. The latter should be protected by a 16A circuit breaker, while 1 mm² requires a 10A breaker (B10 automatic breaker in the fuse box). The stove is often connected with 2.5 mm².
Please check your fuse box—if it has 16A breakers installed on 1 mm² cables, that is very dangerous! Protecting 1 mm² cables with 16A breakers can lead to overheating and potentially cause a fire.
It also depends on how the cables were installed. Are they simply embedded in the wall (flush-mounted), or were conduit pipes used? What type of cable was used? Regular NYM cable? (This should be printed on the cable sheath—if you still have any scraps lying around.)
There are cables with higher current ratings but also higher prices.
By the way, I’m not even sure if 1 mm² cables are approved for house installations at all.
If in doubt, you should hire a professional or an expert to inspect the setup on site rather than relying on guesses over the internet.
Regards,
Micha
K
Karsten 24419 Jan 2012 01:02Hello and many thanks for the detailed answers.
I can confirm there is no problem. I spoke with the electrician who assured me that everything was installed with 1.5 mm² (16 AWG) wiring. There are also 16A circuit breakers installed.
My "expert" had seen an old, inactive cable with probably 1.0 mm² (18 AWG) and thought—because it looked very good—that it was a new line.
Thanks again for the responses. I feel confident again and have learned something new.
Best regards, Karsten
I can confirm there is no problem. I spoke with the electrician who assured me that everything was installed with 1.5 mm² (16 AWG) wiring. There are also 16A circuit breakers installed.
My "expert" had seen an old, inactive cable with probably 1.0 mm² (18 AWG) and thought—because it looked very good—that it was a new line.
Thanks again for the responses. I feel confident again and have learned something new.
Best regards, Karsten
J
JonnYWeeD7 Feb 2012 14:01Hello everyone,
I’d like to clarify a few points. The 1mm² cable size has not been used for a long time, not even as flat cable. Basically, the conductor cross-section is designed according to the upstream circuit breaker:
If you want to draw 16A from a socket outlet, that is the maximum current rating for conventional Schuko sockets. To ensure 16A, you must calculate the cable cross-section based on the length of the cable (loop impedance). For example, a 3x1.5mm² cable can only be installed up to 17m (56 feet) if it is loaded with 16A. If you use a smaller breaker, for example 10A, the cable length can be about 23m (75 feet), but then the maximum current at the socket is only 10A. The other option is to increase the conductor size to 2.5mm², which allows for a maximum length of 25m (82 feet).
So you cannot simply say that 1.5mm² is sufficient. The fact that this is the minimum cable size for flush-mounted domestic wiring becomes clear if a skilled DIY enthusiast tries to buy NYM cable (non-metallic sheathed cable) at a hardware store.
The stove should therefore be connected with 2.5mm² cable, as the manufacturer usually recommends a 20A circuit breaker. Again, pay attention to the length of the cable. Also be aware that new ovens often come with a standard Schuko plug. In this case, only the oven should be on this circuit (socket). The same applies to dishwashers.
Please remember that all circuits accessible to non-professionals must be protected by a residual current device (RCD) since mid-2007. This applies to DIYers as well!
It is best to have a licensed professional electrician review the entire setup.
This is just a very brief and rough overview! The topic is much more complex.
Regards,
JonnY
I’d like to clarify a few points. The 1mm² cable size has not been used for a long time, not even as flat cable. Basically, the conductor cross-section is designed according to the upstream circuit breaker:
If you want to draw 16A from a socket outlet, that is the maximum current rating for conventional Schuko sockets. To ensure 16A, you must calculate the cable cross-section based on the length of the cable (loop impedance). For example, a 3x1.5mm² cable can only be installed up to 17m (56 feet) if it is loaded with 16A. If you use a smaller breaker, for example 10A, the cable length can be about 23m (75 feet), but then the maximum current at the socket is only 10A. The other option is to increase the conductor size to 2.5mm², which allows for a maximum length of 25m (82 feet).
So you cannot simply say that 1.5mm² is sufficient. The fact that this is the minimum cable size for flush-mounted domestic wiring becomes clear if a skilled DIY enthusiast tries to buy NYM cable (non-metallic sheathed cable) at a hardware store.
The stove should therefore be connected with 2.5mm² cable, as the manufacturer usually recommends a 20A circuit breaker. Again, pay attention to the length of the cable. Also be aware that new ovens often come with a standard Schuko plug. In this case, only the oven should be on this circuit (socket). The same applies to dishwashers.
Please remember that all circuits accessible to non-professionals must be protected by a residual current device (RCD) since mid-2007. This applies to DIYers as well!
It is best to have a licensed professional electrician review the entire setup.
This is just a very brief and rough overview! The topic is much more complex.
Regards,
JonnY
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charlieboy2 Aug 2013 23:15Hello, I’m digging up this old thread because it ranks high on Google when searching for cable cross-section.
Can someone explain JonnY’s calculation with a maximum length of 25m at 16A and 2.5mm² cross-section? Although I’m not an expert, I came to the following result for 50m cable length:
Given:
Cross-section 2.5mm² (0.0039 inch²)
50m cable length, meaning 100m conductor length
230V, 16A, meaning 3680W
With this, I calculate (Cu, 20°C (68°F)):
Conductor resistance: 0.71 ohms
Voltage drop: 10.85 volts
Power loss: 165.47 watts
and thus an efficiency of 95.28%.
I heard from a "professional" that anything above 95% is acceptable. Is this information incorrect?
I would appreciate some clarification or the calculation method!
Can someone explain JonnY’s calculation with a maximum length of 25m at 16A and 2.5mm² cross-section? Although I’m not an expert, I came to the following result for 50m cable length:
Given:
Cross-section 2.5mm² (0.0039 inch²)
50m cable length, meaning 100m conductor length
230V, 16A, meaning 3680W
With this, I calculate (Cu, 20°C (68°F)):
Conductor resistance: 0.71 ohms
Voltage drop: 10.85 volts
Power loss: 165.47 watts
and thus an efficiency of 95.28%.
I heard from a "professional" that anything above 95% is acceptable. Is this information incorrect?
I would appreciate some clarification or the calculation method!
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