Electrical

[electau]

What does this EIT code state on the following?

Tripping time of an over current protective device on an earth fault eg MCB.

Voltage drop within an electrical installation.

Earthing. The minimum size of a main earth ME conductor. Equipotential bonding.

The minimum size of an PE conductor. Earthing of conductive metal work that may become energised under earth fault conditions.

The installation of RCDs on final subcircuits. tripping times for an RCD.

The MEN (TN-C-S) and TT earthing systems

Testing and verification of electrical installations.

If the document is in Thai there must be an Edition translated into English otherwise you cannot interpret it.

Standards can conflict in many cases especially if one tries to use both the NEMA and IEC.

[electau]

The earth resistance of a 13mm single copper clad earth electrode at a depth of 1.2/1.8 metres in average moist soil in an areas exposed to the weather is generally about 70 to 100ohms. This is the contact resistance with the soil.

However, this value is a minimum practical value but may rise to over 500ohms. This is why RCDs must be utilised on electrical installations that use the TT or direct earthing system.

Earthing of HV is normally 30ohms at the transformer and for LV earthing 10 ohms. Earthing for these values requires more complex (and expensive) earthing proceedures which are not required for normal electrical installations under AS or IEC requirements.