ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Earth-Loop Testing

A change to our current Regulations,
over here, have required an Earth Fault
Loop test, be carried out after the
installation of electrical equipment, in
any Domestic,Commercial or Industrial
installation.
This test requires that the Installing
Electrician, after the new work is energised, a test shall be done, that
effectively tests the integrity of the
Phase-Earth and the Phase-Neutral
resistance, as this will find the final
size of the O/C protection and also it will
give the size of the expected Fault Current,
under Fault conditions,
Is there a comparative test in the USA
and England?,it's just that now, we are
required to do these tests.
Personally, I have been doing these tests
since I started my time, as an electrical
Boy.
But, what are your thoughts on increased
use of complex test-equipment, to
fault-find power supply problems,
your input, please.

Earth-loop impedance tests and calculations of prospective short-circuit current have figured in the U.K. IEE Wiring Regs. for years.

Go here for a brief extract on the subject.

Loop impedance testers which measure over a brief period so as not to trip RCDs are available here from (for the "el cheapo" versions) about £50 upwards.

Paul,
I have always maintained the idea,that
New Zealand has always been "behind the
times", as far as Electrical Safety,
is concerned, don't get me wrong, this is
not from the people who install, repair
and service, electrical gear over here,
this comes from the Regulators,
We now have a totally botched system over
here and only the Registered Electricians
of NZ are keeping the system honest.
Over here, Paul,we wait for something to
happen, before we do anything about it,
wether it costs a life or not

I think it a fine test to have included, but can find no mention of it becoming compulsory. Either in the Regs or AS/NZ3000 (mine turned up today) :-) I can’t understand why not,
I think our apprentices are very well trained (being one of them) and safety and testing are things that are hammered home at every opportunity.

Cheers CW

That sounds very much like the same principle that most British councils apply to roads. It doesn't matter how much people complain about something being unsafe, it's not until there's a serious accident that anything is done.

As far as making certain tests a requirement under U.K. IEE Wiring Regs. is concerned, the problem there is that as far as residential work is concerned, there is no legal requirement to follow the Regs.

With respect to my earlier comments
on Earth-loop testing, there are a whole
heap of tests required for the Certification of an Electrical Installation
these days.
In New Zealand, you are required to do the
following tests:
Before livening:
1)Insulation resistance tests w/ a 500V
Megohm meter
2)Continuity tests w/ a reliable ohm-meter
3)Earth electrode resistance test,
done with a dedicated test instrument and
electrodes.
After livening:
4)Polarity tests, to ensure correct sequence of supply, done at all socket-
outlets, light fittings and fixed-wired
appliances.
5) Voltage test- to ensure that the voltage is within a certain range for the area of
installation.(This must be done with a
voltage meter that is calibrated by the
local supply authority, this is a local thing,as the S/A wants to know of any
voltage anomalies).
6) Phase Sequence- As we all know,a motor
will run backwards if hooked up around the wrong way,but if this 3 phase supply feeds a large transformer for a rectifier system
supplying a large Emergency lighting Plant,
then you have problems.
7)Earth-Loop Resistance- We've all heard
about this!.
8)RCD Tests- All installed RCD's, must be
tested with an approved RCD tester,
using the test button on the RCD(GFCI),is
not considered to be a test.
The RCD must trip in under 300 milli-seconds @ a trip current of 30 milliamperes.
9)Operational tests- These are done on all
fixed-wired appliances,to make sure that
they work properly and safely.
With all these tests required, consumers
do not want to pay for the time needed to actaully do them, but they are the end users of the said safety tests.
What are we supposed to do, put in the
work then run away, quickly?

All of those you've listed are also "required" by British IEE Regulations, with the exception of #5. (Although naturally a voltage check is made automatically while hooking up the meter for some of the other checks.)

As I've said many times, for residential here it's anything goes. Commercial is another matter, not specifically because of our electrical regulations but because of the "Health & Safety at Work" rules which are enforced by the Health & Safety Executive. Under these rules, many work places now require a full set of annual tests and for records to be kept of the results of earth impedance, insulation values, etc.

I see Fault-Loop Impedance is still only an optional test.
CW

Craig,
Under AS/NZS 3000, the new code,
they have just made Earth-loop impedance
tests mandatory.
Its a shame when non-electrical people
start writing our Regs, it's just like the
whole Downlight thing over again.

Well i will be buggered if i can find where it says it is, got a page number. Down lights oh there is a real can of worm i wonder if they realise just how many are out there.
CW