When needed
Above 7-8 kW of calculated load: electric heating, sauna, 3-phase equipment, EV fast charging. 15 kW — standard three-phase input.
What changes
Input cable 5×6 or 5×10 mm²; a 3-phase meter; a 3P/4P breaker; groups are distributed across phases.
Balancing
Single-phase groups spread evenly: 9 groups → 3/3/3. The imbalance above 15% overheats the neutral.
Voltage 380 or 400?
Nominal 400 V (linear). Equipment is marked 230/400 V. In old networks — 380 V.
Cost
Three-phase connection is not much more expensive than single-phase (standard 550 ₽ up to 15 kW in RF); the meter and the cable are more expensive.
Why design
The project shows the phase distribution, the cable and the metering — the input is done per the TC without rework.
Frequently asked questions
Is this article free?
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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?
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