Ground-Phase Voltage 230V in Server Room: Residual Current Device & Electrician Advice

Question

Hello, I am building server rooms in the company, I was concerned that when the meter touches the grounding pin and the phase, there is a voltage of about 230V, the same if I touch the computer housing and the phase. There is a residual current device installed in the electrical network, which,...

Loker · Answer

N and PE are theoretically at the same potential so a voltage of approx. 230V between phase and any earthed element is perfectly correct unless you have power isolation which I doubt.
The differential current protection will work if the difference in currents in the L and N lines is greater than a certain value (probably 15mA, but I'm not sure), a much smaller current flows through the voltmeter, so the protection will not work.

"Because our unlicensed people do not want to play it and / or have no idea about it" - if they have no idea about something so basic, they are not electricians.

bestler · Answer

It's probably normal. The meter has too little leakage to throw out the differential. But if you use a light bulb instead of a meter, the differential must blow out.

darek_wp · Answer

This is how it should be and the meter itself cannot trip the RCD protection. The protection is activated only after the expiry of the current value greater than that marked on the protection (std 30mA).

niutat · Answer

Hello, the differential has a specific minimum tripping current, the meter is not enough to work. Uups late and can't delete the post anymore

ajpier · Answer

I would sound the alarm as if nothing showed between the pin and the phase.

kris669 · Answer

They don't actually have any idea about it! The transformer's neutran point in TN installations is grounded, so the ground and this point, as well as the outgoing neutral wire from it, are at potential 0 - the same. There should be approx. 230 V between each phase conductor and the neutral or ground conductor (the exact value depends on many factors). The RCD will trip when a certain current flows, which may trip it. Such a current will not flow through the voltmeter (too high internal resistance). RCD release should cause, for example, inclusion of a light bulb / resistor in the phase-to-earth circuit.

domal7 · Answer

hehe, this is how the pin should be connected to the PE conductor or it is zeroed, and therefore it is a different potential, so the meter reading must be different if there was a phase on the pin, but there is also a differential if there was something wrong in the RCD installation To make it break, you can make sure that there is no dangerous voltage on the pins, but it is unnecessary.

lkosc_st · Answer

Only with the earthing most likely ends with the wires in the switching station ... because no one has found the earthing of the building ...

What to connect to the ground and phase to make the differential work (30mA)

kris669 · Answer

You can connect a 7.5 k? resistor of power from 2 W up (2 W is enough for such a short load).

domal7 · Answer

take a makeshift bulb with a socket one wire plug the second wire to L to PE and the differential must work, or connect a receiver to this circuit and short-circuit with some N PE wire and it will also work

kondensator · Answer

The reason is ... at least to read: and more.

Ground-Phase Voltage 230V in Server Room: Residual Current Device & Electrician Advice

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