What is the difference between Tn-S and TN Cs?

bluevelvet New Member. so the main earth cable that goes into the split head would usually be TN-C-S (PME) and the earth cable attached to the cable sheath would be TN-S .

What is TN-S network?

TN-S: TN-S describes an arrangement where separate conductors for Protective Earth (PE) and Neutral are run to consumer loads from a site’s power supply (i.e. generator or transformer). The PE and N conductors are separated in nearly all parts of the system and are only connected together at the supply itself.

What is a TN-C earthing system?

The TNC earthing system always provides a return path for faults in the low voltage grid. The grounding conductors at the transformer and all customers are interconnected. This ensures a distributed grounding and reduces the risk of a customer not having a safe grounding.

Is PME same as TNCS?

PME is a TN-C-S system, where the neutral and earth functions are combined in one conductor (the PEN conductor) on the supply side of the installation. The PEN conductor is referenced to Earth in multiple positions with Earth electrodes, as illustrated in Fig 1.

Does a TT system need an RCD?

In a typical splitboard consumer unit for TT system, the socket-outlet circuits are protected by a downstream 30 mA RCD, which is required by Regulation 471-08-06 (this regulation should be studied for the full requirements). The other circuits are protected by an upstream time-delay (S type) 100 mA RCD.

How is earthing done?

How is Earthing Done? To ensure safety, earthing can be done by connecting the electrical appliance to earthing systems or electrodes placed near the soil or below the ground level. The electrode or earthing mat equipped with a flat iron riser is installed under the ground level.

Is TNS and TNCS PME?

Yes it does. PME supplies are TN-C-S but not all TN-C-S supplies are PME. You could have a TN-C-S supply direct from an on site transformer without the multiple earthing.

Do I need an earth rod with PME?

Since 2013 earth rods have been required on PME systems and the flexibility that some installers used to not fit an electrode was removed from the 18th Edition in January 2019, but the difficulty of successfully fitting an earth rod predates both regulations.

What RCD do I need for a TT system?

30 mA RCD
In a typical splitboard consumer unit for TT system, the socket-outlet circuits are protected by a downstream 30 mA RCD, which is required by Regulation 471-08-06 (this regulation should be studied for the full requirements). The other circuits are protected by an upstream time-delay (S type) 100 mA RCD.