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Posted By Topic: Earth Loop Impedance test in Hazardous Area

Dec 06 2018 15:08

AS/NZS 3000:2007 Clause 8.3.9 states that basically you only need to do an EFLI test on socket outlets that are not protected by an RCD.

The new check sheets for an Initial inspection in AS/NZS 60079.14: 2017 asks to check that the fault loop impedance TN Systems are satisfactory for each device inspected.

Also AS/NZS 60079.17: 2009 Clause 4.12.8 and AS/NZS 60079.17:2017 Clause 4.12.9 mandates the checking of the fault loop impedance at the initial inspection.

So what exactly would you be checking to satisfy the clause in AS/NZS 60079.17 for the fault loop impedance in an Initial Inspection bearing in mind that AS/NZS 3000 only mandates check for socket outlets with no RCD fitted.


Dec 06 2018 18:20

ESR 60(1)(b) requires installations in hazardous areas to be installed, tested, inspected, and connected so as to comply with BOTH "3000" AND "60079.14".

Similar for other special types of installation / part installation.

So any testing requirements in the cited special Standard(s) are additional to those of "3000".

60079.17 may be relevant to inspection / commissioning, via a secondary citation within 60079.14. Similarly it's not directly cited for inspection of high risk PEW under ESR 70. Important to note that these are 2 very different things, and where the Standard refers to "inspection" it doesn't relate to ESR 70 inspection, by an Inspector, of high risk PEW.

60079.17 is directly cited, by ESR 75, for periodic verification of hazardous area installations.

But in all cases this is NOT (yet) the 2017 editions; so put them away on the shelf as they are NOT the documents that are required to be used. Where there is any difference between them the later one cannot be enforced and the cited edition MUST be complied with.

Dec 06 2018 19:32

So when the AS/NZS 60079.14:2017 is cited and the new Initial Inspection Sheets become mandatory and it is also mandatory to check that the fault loop impedance, TN Systems, are satisfactory for each device inspected then what in practical terms does this mean.

What do they want the Inspector to check.

The point I am trying to make is what do we check with regards to the EFLI test.

Do we only check a power socket in the safe area switch room to prove the Earth fault loop Impedance back to the supply transformer or do we have to check every power device that has a circuit breaker feeding it (Motor/Lights/Power Points etc)


Dec 07 2018 09:33

When - eventually - the 2017 editions are cited by ESrs, and assuming the substance of the relevant ESRs doesn't change; then:

Both the inspect-&-test by installer for CoC and the Inspect-for -RoI by Inspector will be i.a.w. 60079.14; and - like now - you'll have to do whatever inspecting & testing "3000" requires PLUS whatever inspecting & testing "60079.14" requires.
If part 14 requires using part 17 for "initial inspection"; then that "secondary citation" will mean following whatever part 17 says for that aspect.

Without checking the details, I'm absolutely certain that checking one socket will definitely NOT be enough. I don't understand how you could possibly think that it might be, after I've told you that you need to comply with BOTH Standards cited by ESR 60.

Periodic verification will continue to be i.a.w 60079.17.

I'm also concerned by your question "what do they want the inspector to check".
If you mean just the inspection carried out as part of checking your work, before issuing CoC; then do whatever the relevant clauses in BOTH Standards say.

If you mean the inspector who carries out the inspection of high risk PEW required by ESR 70; I wonder why you want to know. Any Inspector should have a much better understanding of the ESRs and how citations work, else they shouldn't hold an Inspector PL.
And seems to me the only reason an non-Inspector would care what an Inspector is going to check would be that they suspect their work isn't up to Standard. Nothing to worry about there; Energy Safety actually expect that installers will not always get everything 100%; that's why we have ESR 70 9and Inspector PLs). The answer to what an inspector will check is in ESR 70(3): whatever they have to in order to be satisfied that the work complies & will be safe. There is NO list of particular items for Inspectors to check for any sort of high risk PEW. The Standards don't recognise that Inspectors even exist. Anything in a Standard is for the installer to do.


Dec 07 2018 10:12

The intent of the testing is to determine:
a) there is no evident damage or degradation that indicate the fault loop impedance (TN systems) is not satisfactory; AND
b) automatic electrical protective devices operate within permitted limits.

Both are from the currently mandated detailed inspection checklists in Pt 17 for initial detailed inspection as referenced in Pt 14.

To answer the subsequent question; yes for all circuits relying on a protective earth for operation of protection devices.

Dec 07 2018 15:17

Thanks for the advice.