Choosing Cable Cross-Section: Know the Terms Before You Call an Electrician
Cross-section (mm²) is one of the first terms you'll run into when planning wiring or data cabling. Here's what it actually means — and why 1.5/2.5/4/6/10 mm² keep showing up in DIY projects — without a made-up amperage chart.
How to think about cross-section
Understand what mm² measures
Cross-section (mm²) describes the conductor's area — it affects resistance and heat dissipation, not a fixed current rating.
Remember: safe load isn't fixed
It always depends on the installation method (free air, conduit, in-wall), ambient temperature, cable length, and how cables are bundled.
Know the common DIY sizes
1.5 / 2.5 / 4 / 6 / 10 mm² are the sizes you'll most often see in home wiring — a starting point for the conversation, not a final answer.
Check the datasheet and regulations
Before connecting anything, check the manufacturer's datasheet, local wiring regulations, or ask a certified electrician.
What to know about cross-section sizes
common DIY sizes
1.5 / 2.5 / 4 / 6 / 10 mm² — size labels, not an amperage chart.
mm² is area, not power
Cross-section describes the conductor's area in square millimetres — on its own it doesn't tell you what load you can safely connect.
Circuit type shapes the choice
Lighting, socket, and higher-power circuits typically use different sizes — but the exact match comes from the project and regulations, not a fixed table.
Solid vs stranded
Solid conductors suit fixed in-wall or conduit installation and terminal blocks; stranded conductors suit anything needing flexibility, like moving equipment or cable trays with motion.
Data cable follows different logic
UTP/FTP or KNX bus cable uses completely different sizing and construction principles than power cable — don't mix them up.
Route power and data separately
It's best to run power and data/low-voltage cables in separate conduits or with enough distance between them to avoid interference.
What's included in a consultation
We help you figure out what fits your project — no pressure to buy.
- {'t': 'Existing wiring review', 'd': "We look at what's already in place and what's planned."}
- {'t': 'Circuit list walkthrough', 'd': 'We go through which circuits and devices are planned together.'}
- {'t': 'Routing recommendations', 'd': 'How to separate power and data cabling, where shielding helps.'}
- {'t': 'Pointers to the right rules', 'd': 'Where to look — datasheet, IEC standards, local wiring rules.'}
- {'t': 'A clear next step', 'd': "If needed, we'll point you to a certified electrician."}
Frequently asked questions
Why doesn't this page give an 'X mm² for Y amps' table?
Because that table would be misleading — safe current always depends on installation method, temperature, length, and local regulations. The right number comes from the cable's datasheet or a certified electrician, not a generic table online.
What does mm² actually mean on a cable?
It's the conductor's cross-sectional area in square millimetres — the bigger the number, the 'thicker' the conductor. It affects resistance and heat dissipation, but on its own doesn't state a safe load.
What's the difference between 1.5, 2.5, 4, 6, and 10 mm²?
They're the sizes you'll most commonly meet in home wiring — from thinner conductors typical of lighting-type circuits up to thicker ones used for higher-power circuits or panel connections. The right choice for each circuit comes from the project, not a fixed list.
Can solid and stranded conductors be mixed in one circuit?
Better not without thinking it through — termination points (terminal blocks) often need different handling for each. If you're unsure, ask an electrician.
When does data cable need shielding?
Shielded cable (FTP/STP or shielded LiYCY) helps in electrically noisy environments or on longer runs near power cable — but the shield must be grounded correctly, or it can actually make things worse.
Not sure what cross-section fits your project?
Book a consultation — we'll go through your circuits together and flag what to confirm before you shop or call an electrician.