Line-to-neutral voltage is the electrical potential difference measured between a live conductor (phase) and the neutral (N) in an AC power system. It is the voltage most commonly used for single-phase loads, including many household circuits and single-phase EV charging. In typical European low-voltage networks, line-to-neutral voltage is 230 V.
What Is Line-to-neutral Voltage?
Line-to-neutral voltage (often written as V<sub>LN</sub>) is measured:
– Between L1–N, L2–N, or L3–N in a three-phase system
– Between L–N in a single-phase system
It differs from line-to-line voltage, which is measured between two phases.
In a balanced three-phase system, line-to-neutral voltage relates to line-to-line voltage as:
– V<sub>LN</sub> = V<sub>LL</sub> / √3
That’s why a 400 V line-to-line supply corresponds to about 230 V line-to-neutral.
Why Line-to-neutral Voltage Matters in EV Charging
Line-to-neutral voltage determines how much power can be delivered in single-phase charging and affects charger configuration and site electrical design. It impacts:
– Whether an AC EV charger can be wired for single-phase operation
– Maximum charging power at a given current limit
– Circuit design (neutral conductor sizing, protection, and earthing checks)
– Charger compatibility where only single-phase supply is available (many homes and small businesses)
For many destination and residential installations, line-to-neutral voltage is the key value used to size the charger and verify the available electrical capacity.
How Line-to-neutral Voltage Affects Charging Power
For single-phase AC charging, power is commonly estimated using:
– P ≈ V<sub>LN</sub> × I × PF
Where I is current and PF is power factor (typically close to 1 for EV charging).
Practical examples (typical 230 V supply):
– 10 A ≈ 2.3 kW
– 16 A ≈ 3.7 kW
– 32 A ≈ 7.4 kW
If the actual line-to-neutral voltage drops under load (for example due to long cable runs or grid conditions), the charger may deliver less power and charging time increases.
Line-to-neutral Voltage vs Line-to-line Voltage
These two values are often confused, but they describe different measurements and use cases:
– Line-to-neutral (V<sub>LN</sub>): phase-to-neutral, used for single-phase circuits and many building loads
– Line-to-line (V<sub>LL</sub>): phase-to-phase, used for three-phase power ratings and calculations
EV chargers may use either depending on configuration:
– Single-phase charging uses L–N (line-to-neutral)
– Three-phase charging uses L1–L2–L3 with V<sub>LL</sub> as the primary voltage reference
Common Line-to-neutral Voltage Levels
Line-to-neutral voltage depends on the regional grid standard:
– 230 V – common across most of Europe
– 120 V – common in North America for standard outlets
– Other values exist in specific countries and industrial networks depending on transformer configuration
Chargers typically specify acceptable operating ranges (for example ±10%) because real-world voltage varies with load and network conditions.
Practical Considerations for Installers and Site Owners
Correctly confirming line-to-neutral voltage supports safe, compliant EV charger installations:
– Check that neutral is present and correctly connected (especially in older buildings)
– Confirm supply capacity (main fuse rating, available current per circuit)
– Manage voltage drop by selecting correct cable cross-section and routing
– Choose protection devices appropriate for the system (MCB, RCD, surge protection)
– Align charger configuration with the site’s supply type (single-phase vs three-phase)
Related Glossary Terms
Line-to-line voltage
Single-phase supply
Three-phase supply
Voltage drop
AC EV Charger
Power factor
MCB (Miniature Circuit Breaker)
RCD (Residual Current Device)
Load balancing
Power throttling