Help with certification please

sjm · Nov 20, 2011

Hi guys, I would greatly appreciate your help if possible please.

The system in question is TNCS at the origin. It feeds 1 x consumer unit with MCB feeding an office in the house grounds using SWA cable.
The office consumer unit has an earth rod, Ze of 170 ohms so not connected to the TNCS system.
The office consumer unit feeds another small consumer unit using 10 mm T+E to feed 2 x wall heaters.

The question is how would you record this on an EIC?

Origin as the TNCS main supply, then use 2 lines of the results sheet to record the 2 x sub main circuits, or origin as the TT office supply and use the designated line for a consumer unit that is remote from the origin?

Thanks in advance.
Steve.

MarkieSparkie · Nov 21, 2011

My preference is to use 2 EICs. On a small installation such as yours this may seem excessive, but I think it's a neater layout particularly with larger installations and thus has become my standard method. Others will want to do this on one EIC to save the registration cost of an additional EIC. The first EIC for the house distribution board (DB1) at the origin and the sub-main and a second EIC for the office distribution board (DB2) and it's final circuits. On the second EIC refer the measured loop impedance at DB2 as Z[SUB]DB2[/SUB] as Z[SUB]E[/SUB] can only exist at the supply origin (DB1). The choice is yours, but the principle is the same.

Deleted member 26818 · Nov 21, 2011

It should really be one EIC, with the details of the origin for the TN-C-S part of the system recorded.
You should then produce a separate schedule of test results for each board, and as Markie says, refer to the first TT board as DB2.
However, there's nothing really preventing you from using the one schedule, as long as it's clearly shown that you are using the one schedule for two boards.
There's no requirements in the Regulation about how the information is recorded on Certification, just a requirement to record it.