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Associate

Join Date: Aug 2014
Posts: 35

TNC &TNS Earthing System

01/07/2015 11:13 PM

What happen if TNC earthing system is connected downstrem of TNS earthing system .In google it is mentioned that this arrangement prohibited but did not found any proper explanation.

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Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#1

Re: TNC &TNS earthing system

01/08/2015 12:01 AM

What is the diversity factor?

Did you look at the code books?

Are you a student?

Your questions seem......................................................................curious.

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Participant

Join Date: Jan 2015
Posts: 4
#2

Re: TNC &TNS Earthing System

01/08/2015 4:31 AM

TNC to TNS no problem (say it 3P+PEN to 4W (3P+PE and N) is olny separate between N and E

TNS to TNC is forbidden: Danger life parth exposed safety reason and for sure the upstream earth leakage will trip due to N and earth connected in TNC (PEN) with additional rods.

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Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33392
Good Answers: 1817
#3

Re: TNC &TNS Earthing System

01/08/2015 11:01 AM

It's my understanding that TN-C is no longer used....

"The TN-C should be avoided since rank 3 harmonics and multiples of 3 flow in the PEN (added to neutral current) and prevent the latter from being used as a potential reference for communicating electronic systems (distributed intelligence systems). Moreover, if the PEN is connected to metal structures, both these and the electric cables become sources of electromagnetic disturbance.

Note

The TNC-S (TN-S downstream from a TN-C should also be avoided even though risks are smaller)."

http://www2.schneider-electric.com/documents/technical-publications/en/shared/electrical-engineering/dependability-availability-safety/low-voltage-minus-1kv/ect173.pdf

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Guru

Join Date: Jul 2007
Location: Commissariat de Police, Nouvions, occupied France, 1942.
Posts: 2599
Good Answers: 77
#4

Re: TNC &TNS Earthing System

01/09/2015 12:17 PM

Because sooner or later, someone will get electrocuted.

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