Understanding Earthing Systems

What in the world is TT and TTNS? Please make question more clear without acronyms.

Hi :Ronsargent

A earthing system are classified with a three letter designation.

The first letter indicates the supply earthing arrangement :

T - indicates that one or more point of the supply are directly earthed.

The second letter indicates the installation earthing arrangement :

T - all exposed conductive metalwork connected directly to earth.

N - all exposed conductive metalwork connected directly to earthed supply conductor.

The third letter indicates the earthed supply conductor arrangement :

S - separate neutral and earthed conductors.

I hope than you can understand the technical team use.

Best Regards

Thanks for the info. Unfortunately, I have limited experience with the question. Therefore, I will leave the answer up to others.

Do you honestly not know what these systems are? I suggest you do some study.

To the OP, the best answer you can find to your question lies with IEEE (IEC). If you don't have access to such documents, you can find a reasonable general overview on wikipedia...but be advised that this is an OVERVIEW & is not 100% correct or detailed.

See Schneider's Cahiers techniques:

http://www.schneider-electric.com/corporate/en/products-services/technical-publications/networks.page?

Refer nos. 172 & 173.

The answer may be found within the pages of a number of on-line encyclopaediae on the subject of "electrical earthing systems".

TT is usually found in rural areas, as it is not ideal to rely on an overhead earth conductor that may be brought down by tree branches, landslides etc. It is far better for the customer to supply an earth electrode.