eic help

[daveygh]

Hi all

done my 2391 a few years ago but never got a chance to use it properly as my old firm had 2 full time testers, so obviously a bit rusty. i need help on a couple of entries on the NICEIC electrical installation cert ICN2

the work i'm doing is adding some lighting and power to an existing DB on the 8th floor and the DB is connected to a rising busbar, i have no access to the main incoming supply so how do i find out

page 2 nature of supply parameters:the Earthing arrangement, the PFC, external earth fault loop impedence Ze, and also the characteristics of primary supply overcurrent protective devices.

page 5 :characteristics at this distribution board

The DB is mechanically fixed via trunking to the tap off unit and has a 25mm earth cable from the busbar casing to the db so how do i get the Zs without disconnecting all the out going earths from the board (including existing circuits already in the board)

and finally as the board is 3 phase but all outgoing supplies are single phase do i do the pfc as the highest of the 3 phases or do the rule of thumb and double the reading

lastly i have fitted some merlin gerin rcbo's and they still trip when i do loop test on the circuits even though the robin tester has D lock, can i substitute the rcbo for a mcb, get the readings ,then put the rcbo back

thanks:C

 

[kme]

OK:

1. by enquiry - you should have access to the last PIR or the original EIC - just add the letters "NV" after the entries (not verified).

Zs doesn`t require any removal of earths - it is taken with `em connected. You`re thinking of Ze, which you cannot do without shutting off the whole installation.

PFC - phase-phase X2.

You "can", but you "shouldn`t". alternative is by calculation (Zs(DB) + R1+R2)

HTH

KME

 

[daveygh]

Thanks Kme the only problem is we dont have the original EIC or last pir i guess i'm going to have to track down Maintenence of the building and se if they can get me the info.

thanks anyway

 

[kme]

Maintenance manager has to have this info, by law. FRA & H&S can request to see it.

You cannot sign your work off without either that paperwork; or powering down the whole installation to do your own tests. Tell `em that - they`ll "find" it for you!!

KME

 

[daveygh]

hi again

one other quick question:

on page 2 of the icn the part that says protective bonding conductors am i right in saying the earthing conductor is the earth at the 8th floor DB (25mm) and the main protective bonding conductors are the earths coming from this DB (6mm) which only do the ceiling grid and raised floors. There are no gas supplies on this floor and the kitchen sink pipework was already cross bonded or are these earths the main bonding conductors in the basement plantroom to which i have no access.

thanks :C