NU Series – Switching Devices with Neutral Conductor Monitoring
(DFS NU & DHS NU / NUS)
Neutral Conductor Monitoring: Why the Doepke NU Series Matters
Electrical faults don’t always announce themselves loudly. One of the most dangerous — and often overlooked — issues in electrical installations is a failure of the neutral conductor. When this happens, the consequences can range from damaged electronic equipment to serious fire hazards.
The Doepke NU series of residual current circuit-breakers (DFS NU) and main switches (DHS NU / NUS) was developed specifically to address this risk — by continuously monitoring all live conductors, including the neutral.
The Hidden Risk of Neutral Conductor Failure
In three-phase systems, loads are rarely perfectly balanced. If the neutral conductor is interrupted while line conductors remain energised, a neutral point shift occurs. This can lead to:
- Dangerous overvoltage or undervoltage
- Damage to sensitive electronic equipment
- Malfunctions in connected devices
- Increased fire risk in worst-case scenarios
Traditional protective devices often do not detect this condition in time — or at all.
The Solution: Safety Through Mains Monitoring
The NU series from Doepke introduces active mains monitoring as a safety standard.
How it works:
- All line conductors (L1, L2, L3) and the neutral conductor (N) are continuously monitored
- Faults in the supply are detected immediately
- The system reacts by disconnecting the installation in a controlled and safe manner
This approach significantly reduces the risk of secondary damage caused by unstable supply conditions.
DFS NU & DHS NU – What’s the Difference?
DFS NU (Residual Current Circuit-Breaker)
- Monitors line conductors and neutral conductor
- In the event of a fault, all conductors including neutral are disconnected
- Ideal where complete isolation is required for maximum safety
DHS NU / DHS NUS (Main Switch / Switch-Disconnector)
- DHS NU: monitors line conductors and neutral
- DHS NUS: additionally monitors the neutral rail via a dedicated sensor
In fault conditions:
- NU devices disconnect all conductors
- NUS devices disconnect line conductors only
This allows for flexible system design depending on regulatory requirements and installation architecture.
Key Benefits at a Glance
✅ Continuous monitoring of the neutral conductor
✅ Protection against neutral point shift
✅ Reduced risk of equipment damage and fire
✅ Clear safety advantage in asymmetrically loaded systems
✅ Suitable for modern, sensitive electrical installations
Typical Applications
The NU series is especially suited for installations where reliability and safety are critical:
- Commercial and industrial buildings
- Installations with sensitive electronic equipment
- Systems with uneven phase loading
Facilities where continuity of safe power supply is essential
Available Models (Examples)
- DFS 6 040-4 / 0.03 A NU
- DFS 6 063-4 / 0.03 A NU
- DHS 6 – 063 NU
- DHS 6 – 063 NUS
(Exact selection depends on rated current and system requirements.)
Why Choose Neutral Monitoring Today?
As electrical installations become more complex and equipment more sensitive, neutral conductor monitoring is no longer optional — it’s preventative safety.
The Doepke NU series provides a robust, future-proof solution that actively prevents faults instead of reacting after damage has already occurred.