M
Mr.Simple
Hi, firstly I wanted to publish this in the DIY Forum as I am not an electrician, however the DIY forum appears locked and new members cant post there.
So, my problem is trying to interpret an EIC for a neighbour. I will say again I am not en electrician however I do know about electrics, I have a degree in electronic engineering and my neighbour wanted some technical help.
He has just had an extension and this was completed correctly by a NICEIC Domestic Installer and the system tested. ON page 2ofthe NICEIC Domestic installation Certificate, under "Supply Characteristics" is a value for External Earth Fault Loop impedance Ze of 0.35 Ohms (this is a TNCS system, and I think the ma permissible Ze is 035 Ohms). My understanding f Ze is that it measures the impedance of the circuit from the customers from Consumer unit main earth (disconnected from the board) through the suppliers transformer and back along the live to the live side of the main breaker (hope that this is right). If this is correct then it appears to be on the limit but is in tolerance, so everything is ok.
However in the sexton "Particulars of the installation at the origin' there is another box labelled Measured Ze,and this is 0.14 Ohms. Basically I simply don't understand the difference between the two. Furthermore also in the "Supply Characteristics" area is a box called Prospective Fault Current Ipf recorded as 1.8kA Now using Ohm law and assuming the supply is actually 250v (yes I know that Uo is 230v, but isn't that a sop to the EU) 250 divided by 1800 comes out at 0.138 Ohms, which is near enough measured 0.14 Ohms. So where does the vale 0.35 Ohms come from in the Supply Characteristic area?
I also have an earlier Periodic Inspection Report dating from 2004, before the extension and new wiring, which talks about the Ze as being "measured as 0.32 which is close to the supply limit o 0.35, caution advised" (what caution did they expect my neighbour to take?). This is recorded in the "Supply characteristics" of the Periodic Inspection Report with the comment in observations Section.
Can someone please clarify why there are two entries for Ze on the NICEIC Domestic Electrical Installation Certificate and why they should be different.
Many thanks
So, my problem is trying to interpret an EIC for a neighbour. I will say again I am not en electrician however I do know about electrics, I have a degree in electronic engineering and my neighbour wanted some technical help.
He has just had an extension and this was completed correctly by a NICEIC Domestic Installer and the system tested. ON page 2ofthe NICEIC Domestic installation Certificate, under "Supply Characteristics" is a value for External Earth Fault Loop impedance Ze of 0.35 Ohms (this is a TNCS system, and I think the ma permissible Ze is 035 Ohms). My understanding f Ze is that it measures the impedance of the circuit from the customers from Consumer unit main earth (disconnected from the board) through the suppliers transformer and back along the live to the live side of the main breaker (hope that this is right). If this is correct then it appears to be on the limit but is in tolerance, so everything is ok.
However in the sexton "Particulars of the installation at the origin' there is another box labelled Measured Ze,and this is 0.14 Ohms. Basically I simply don't understand the difference between the two. Furthermore also in the "Supply Characteristics" area is a box called Prospective Fault Current Ipf recorded as 1.8kA Now using Ohm law and assuming the supply is actually 250v (yes I know that Uo is 230v, but isn't that a sop to the EU) 250 divided by 1800 comes out at 0.138 Ohms, which is near enough measured 0.14 Ohms. So where does the vale 0.35 Ohms come from in the Supply Characteristic area?
I also have an earlier Periodic Inspection Report dating from 2004, before the extension and new wiring, which talks about the Ze as being "measured as 0.32 which is close to the supply limit o 0.35, caution advised" (what caution did they expect my neighbour to take?). This is recorded in the "Supply characteristics" of the Periodic Inspection Report with the comment in observations Section.
Can someone please clarify why there are two entries for Ze on the NICEIC Domestic Electrical Installation Certificate and why they should be different.
Many thanks
