Ze

brizospark · Jan 11, 2011

Had a bit of a problem today

I was carrying out a PIR in a car hire kiosk in an airport today. The small kiosk had it's own DB supplied via a SWA cable.

For recording the Ze on the test sheet I understand that this has to be carried out at the supply entry point but with working in an airport everything is 100 times more stringent than working most places, I was not permitted access to the main switch room.

So I measured the EFLI at the DB main switch 60947-3 which was 0.28 Ohms

Would it be satisfactory to record this value as the Ze or would I be better off putting L/M in the Ze box?

Sparky Ninja · Jan 11, 2011

That's a surprisingly good reading.
Record this value as the Zdb, and put on your reports limitation to the true origin of the installation. You could ring the supply authorities, or maybe somewhere there, so that you can gain the information by enquiry..

IQ Electrical · Jan 11, 2011

brizospark said:
Had a bit of a problem today

I was carrying out a PIR in a car hire kiosk in an airport today. The small kiosk had it's own DB supplied via a SWA cable.

For recording the Ze on the test sheet I understand that this has to be carried out at the supply entry point but with working in an airport everything is 100 times more stringent than working most places, I was not permitted access to the main switch room.

So I measured the EFLI at the DB main switch 60947-3 which was 0.28 Ohms

Would it be satisfactory to record this value as the Ze or would I be better off putting L/M in the Ze box?

Technically, this value is Zs or Zdb, as you say, there is only 1 Ze for an installation and I guarantee you that you will never get to isolate the installation and measure it!

I would put LIM in the Ze box and include the reasons in your 'extent and limitations' box ie. 'main supply characteristics not verified by client request'