Temperatures
PVC insulation — 70 °C; XLPE — 90 °C. The cable should not work at the limit — keep 10-20% margin.
Derating factors
Ambient above 30 °C — reduce by 3-10%; bundled cables — 0.7-0.9; in insulation — 0.5-0.6. The tables in IEC 60364-5-52.
Symptoms
Warm cable along the wall, smell, darkening of the box, tripping breaker. Measure the temperature with a thermal camera.
How to check
Compare the load current with the cable capacity by the installation method. GorkyCAD does it for every line.
Fixes
Increase the section, split the group, improve cooling (remove the insulation).
Why it matters
Overheating destroys the insulation — a short circuit or a fire. The check takes a minute and costs nothing.
Frequently asked questions
Is this article free?
Yes, all articles and calculators are completely free.
Yes, all articles and calculators are completely free.
Where can I run calculations?
The site offers 21 free calculators: cable sizing, breakers, RCD, voltage drop and more.
The site offers 21 free calculators: cable sizing, breakers, RCD, voltage drop and more.
How do I prepare an electrical project?
In GorkyCAD Pro: plans, panels, calculations and a PDF set for free.
In GorkyCAD Pro: plans, panels, calculations and a PDF set for free.
Found an error in the article?
Write to hello@gorkycad.pro — specialists will review and correct it.
Write to hello@gorkycad.pro — specialists will review and correct it.