N-conductor disconnect terminal blocks: Where are they mandatory, and why can they be useful even outside the standard?
Contrary to common misconceptions, neutral conductor disconnection isn’t always mandatory for electrical installations, such as in private residences. Nevertheless, it can also be useful where it is not directly required. Why and where it is actually required by law? Let’s take a look at the relevant standards.
Where is N-disconnection required?
N-disconnection devices (per DIN VDE0100-718) are mandatory in public buildings, workplaces or buildings where people gather. These include restaurants, shopping malls, train stations, airports, parking structures, apartment buildings, theaters and stadiums. In those places, the insulation resistance must be measured frequently, and at conductor cross-sections under 10 mm 2, measurement must be possible without disconnecting the conductors. N-disconnection devices are also mandatory for neutral conductors if the workplace has an increased fire risk, according to the VdS 2033 directive.
Why is N-disconnection useful?
With N-conductor disconnect terminal blocks, an insulation measurement can be performed without disconnecting the neutral conductor according to DIN VDE 0100-482. But there is also a practical benefit: N-disconnect terminal blocks greatly accelerate electrical system troubleshooting – thanks to the sliding disconnect function. Simply switch off all fuses, pull all N-disconnect sliding links from the N-busbar and then, with the RCD switched on, switch each individual circuit back on. After all, do you have the time and money for hours of troubleshooting in either private or commercial installations?