30/08/2026
WHY DO MANY ELECTRICIANS RECOMMEND 4MM CABLE BUT STILL USE 2.5MM ?
There is an interesting contradiction in electrical installation.
The demand for 2.5mm cable is significantly higher than that of 4mm cable, yet when you ask many electricians what cable size should be used for appliances like air conditioners, water heaters, cookers, and other heavy loads, the common answer is:
“Use 4mm.”
But here is the question:
How many of them actually use 4mm when installing those loads?
Knowing the recommended cable size is one thing. Understanding why that size is recommended and applying it correctly is another, or perhaps they are using 2.5mm because of cost, on the other hand if 4mm is cheaper than 2.5mm would they be using 4mm?
Cable selection should not be based on what electricians commonly say or what has always been done on previous jobs. It should be based on factors such as:
• The appliance’s rated power and current
• The length of the cable run
• Voltage drop
• Protective device rating
• The applicable electrical regulations and manufacturer’s requirements
A 2.5mm cable may be perfectly suitable for some loads, while another installation may require 4mm or even a larger conductor.
The goal is not to use the biggest cable. The goal is to use the CORRECT cable size for the actual installation.
As electricians, we should stop relying solely on “this is what we normally use” and start making our cable-selection decisions based on calculation, standards and the actual conditions of the installation.
