How to choose the right cable cross-section
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Choosing the correct electrical cable cross-section is one of the most important steps when building or repairing an electrical installation. An error can lead to overheating, damage to appliances, or fire.
What is a cable cross-section?
The cable cross-section is the area of the conductor's cross-section, measured in square millimeters (mm²). The larger the cross-section, the more current can flow through the cable without overheating.
The basic rule
The cross-section is chosen according to the current of the consumer. If the current is greater than the permissible limit for a given cross-section, the cable will overheat — even if the circuit breaker does not trip immediately.
Approximate table
- 1.5 mm² — lighting, up to 10A
- 2.5 mm² — sockets, water heater, up to 16A
- 4 mm² — air conditioner, cooker, up to 25A
- 6 mm² — electric oven, heat pump, up to 32A
- 10 mm² — main power cable, up to 50A
Important factors when choosing
In addition to the current, the following should also be considered:
- Cable length — for longer runs, the voltage drops, requiring a larger cross-section
- Installation method — a cable in a conduit heats up more than an exposed cable, so the permissible current is lower
- Number of cables — if several cables are laid together, they heat each other up
Copper or aluminum conductors?
Copper conductors conduct current better and are more flexible. For domestic installations, copper cables are always recommended. Aluminum ones are cheaper but have higher resistance and require a larger cross-section for the same current.
Practical advice
When in doubt, always choose one size larger cross-section. The price difference is small, and the safety is significantly greater.
Explore electrical cables in our store — available in various cross-sections and lengths.
See available models in our store.
Important: Electrical installations must be carried out by a qualified electrician. The information in this article is for educational purposes only.