Online assistance for electrical trade people in New Zealand and Australia Login  |  Register  |   Forgot Password
Assistance for electrical trade people
 

 

 

 


Click here to send Ron a pdf document for publication on this Topic

Documents must be less than 200k in pdf format

Posted By Topic: Works and ROI

CraigW
Mar 20 2018 09:41

We are having a debate as to whether or not a site requires either a COC/ROI or a ESC, a street has had its overhead supply undergrounded with the poles left in place and new connections from newly installed pillars to the existing overhead connections, no one want to pay to get rid of their overhead cables.
Apparently the person that engineered the job insists they should all have COC\'s and ROI\'s, any thoughts?

   

TheDon
Mar 20 2018 10:01

From what you describe all the work has been done on the Network and nothing on any installations , would that be correct ?
   

AlecK
Mar 20 2018 10:31

If all work was on \"works\", then no CoCs are required by ESRs, because the work is not done \"on an installation\" [ESR 65(1).

Similarly no RoIs are required by ESRs, because no \"high risk\" PEW has been done[ESRs 70(1) & 6A(2)]. Some of the work may have been done on \"mains\" but only on the section of mains upstream of the \"point of supply\"; which is \"works\" & not \"installation\" (another example of \"mains work\" that is not \"high risk\" PEW, though this time not for the usual reason of being \"low risk\").

On the other hand, there\'s nothing to prevent them being CoCs or RoIs being issued even when they don\'t have to be. Except that CoCs are required to certify compliance with \"3000\"; and this work may well not comply. For Part 1 there would have been a Certified design; but it\'s possible that the work does actually comply with Part 2.

However ESCs ARE required, for each connection made to an installation; by ESR$ 74(1AA)(c); because work has been done on fittings that supply installations.
   

zl2aj
Mar 20 2018 16:35

Check the networks definition of \"Point of Supply\" in the network connection standard as, because there is no property boundary to cross, the POS is defined by the network (Section 2 (3) (d) of the Act).

If the work you are doing is after the POS then it is high risk installation work (mains) and would need a CoC / RoI.
   

gregmcc
Mar 20 2018 17:12

Just done 100 or so properties along a street in Auckland overhead to underground conversion, along with that were a whole bunch of new street lights, While the company that done the works (line workers) done the supply end of the street lights, the installation crew (Electricians) done the street light end of the supply, inside the street light was a N&E bar, a MEN link, so as the work was mains work we got inspections done on each street light.
Regardless of the location of the street light it meets the definition of an installation so it would require a ROI
   

pluto
Mar 20 2018 21:07

Looks like another area that does NOT understand the systems of supply used by streetlights. It is most important street lights be wired correctly when there is NO true MEN system of supply (with NO earth electrodes) to reduce the electrical shock potential to aminimum.

The knowledge of the so called MEN supply system is only correctly known by a few, you need to ask oldtimers who worked for an old supply authority for the key points.

As a general rule if the streetlight is supplied by a lines company distrinution cables AND there is NO MEN switchboard (providing the supply connection the system of supply is TN-C. In this supply system the earthing is done using the neutral conductor and routine testing from time to time.
Also need a good screened cable termination box with a fuse link for the streetlight fitting active supply.

If the streetlights is being fed from an electrical installation (downstream of the main switchboard only)the streetlight is wired using TN-C-S, the fitting being earthed by a protective earth conductor and active and neutral being the power supply inlet connections.

With the rollout of LED streetlights replacing the old sodium streetlights you need to get the correct facts of how streetlighting is arranged. If you find some old series connected streetlighting that system is not satisfactory for LED replacements.
   

Sarmajor
Mar 21 2018 06:42

In many areas street lights are installed as men installations complete with earth electrodes.
This is being done in works in new subdivisions and they are being inspected before livening.

   

pluto
Mar 21 2018 07:54

If another systemm of supply, TT, is to eb uintroduced it looks like there is a major problem that most do NOT understand the MEN system of supply.

There are places when TT is better but we need to retrain alsmost everyone what an MEN supply really means in real life. And then teach everyone the TT system of supply.

Looks like we have found a good topic for upcoming competency courses instead of some of driblle I see being rolled out to apply from this year.
   

zl2aj
Mar 21 2018 08:17

Understanding the MEN system of supply is a separate (but equally valid) issue Pluto. The OP asked about whether an inspection was required. Answer - it depends on the network connections rules (and thus agreement to where the POS is with the council).

For those that do such work - the most important thing you need to understand is which side of the POS you are working on. Because it changes everything.

Works side - working on network asset, to thier design standards, their testing procedures, and their certification rules (if any).

Installation side - working on customer asset, to AS/NZS 3000, testing to section 8 of AS/NZS 3000, certifying in accordance with the ESRs.

Failure to understand where the POS is, and where you are working in relation to it, means it is likely you will get things wrong.

Historically many supply companies decided to treat streetlight columns as installations to remove their liability over the cable supplying the column. In many cases it served no network benefit to retain ownership of it so it was divested back to the council. A misinterpretation by some of the Act also suggested appliances could not be connected directly to works but had to go via an installation (this was later clarified as incorect by a Energy Safety newsletter release). However many networks liked the perceived increase safety around having each streetlight (or group of streetlights) as an installation with TN-C-S earthing rather than TN-C. That said there may as you point out be issues going forward with the mixed system that now is prevalent. Confusion with some not understanding the systems could lead to mistakes being made by those that dont take due care to understand the systems and why they exist.

The risk now is many new streetlight columns are fully insulated when burried by a tough coat layer sprayed onto the galv base. So inherent earthing of the column can not be relied upon. Touch voltages need to be managed within the limits of AS/NZS 60479. To achieve this it requires cooperation between all of the entities that own assets in the road reserve. Bonding between any conductive material (irrespective of ownership) that is 2 metres or less apart (length between outstretched arms + safety margin) should be mandatory. Then connection to the greater urban electrode mat should dissipate any fault currents to within safe limits. That is the challenge.
   

pluto
Mar 21 2018 08:55

ZL2AJ

Yes you understand the issues, but what a mess the lazy line companies are making and sooner or later it will all have to be sorted out and be done correctly.


   

zl2aj
Mar 21 2018 10:32

In fairness to the lazy lines co\'s - they are (in various ownership models) all private companies striving to give return to their owners. If this laziness is deemed to be an issue by the regulator, would they not have regulated it?

The 29 different sets of rules is no different to the 29 different public safety management systems, 29 different network design criteria (standards) etc. Yes it is a challenge but the regulator either doesnt see a need for broad regulation (due to lack of safety incidences to justify such) and is keen to leave it in the hand of 29 different engineering teams, or hasnt come up with a solution that would reduce the perceived risk.

Thus here we are :).


   

AlecK
Mar 21 2018 11:44

I think you\'ll find that the regulations already cover it, and allow for all systems;
lights as part of works and lights as installations (either individually or in groups).

Enforcement of those regulations is another matter entirely; but if / when an incident occurs it\'s likely some set-ups will be found to be in breach - having been done in a way that is \"neither fish nor fowl\".

Largely because networks have still not realised that they lost \"Supply authority\" status in 2993; and still think they can make up their own rules and/or apply their own interpretations of both ESRs & supply Regs.

I suspect the demand for RoIs is due to ignorance, thinking that because it\'s \"mains work\" it must be \"high risk\".

You\'re right that knowing which side of POS you are working on is crucial to knowing what rules apply. If asking a network for this information, best to get it in writing, as the answer is likely to vary depending on who you ask and whether they are trying to shift liability away from the network.

Of course for streetlights-as-works there may be no POS. But for undergrounding distribution while retaining o/h supply to installations (what the OP was about); there definitely will be a POS for each. Generally at position where \"mains\" cross the property boundary. But even if no PEW was done downstream of these POSs (no PEW \"on an installation\", ESCs are still required by ESR74A for the connection of each installation to new distribution system.

Just as they are for all new connections - but just try getting an ESC from a network. Or even getting them to wait for the mains to be certified & inspected before connecting at least the phase and often the active(s) as well. Leaving the supply fuses out does NOT satisfy ESRs. They get away with this sort of stuff because even if the electrician and/or inspector know better, the network is in a strong commercial position to just do what they want to without much chance of being reported.



   

zl2aj
Mar 21 2018 14:29

Networks I deal with all know the rules around ESR 74A and ESR 73A (not connecting conductors until safe).

I thought the question was around streetlights in road reserve (hence no property boundary to cross) and thus reliant only on the networks written definition.
   

Blazesto
Mar 29 2018 15:20


\"I thought the question was around streetlights in road reserve (hence no property boundary to cross) and thus reliant only on the networks written definition.\"

A lot of the time the street light is owned by the local council, so the POC from network to consumer is the fuse in the pole.

The have an MEN board inside using the pole as the electrode.
   

AlecK
Mar 29 2018 15:45

which might be ok; except that \"stret light pole\" is NOT included on the list of acceptable earth electrodes for an installation.
   

zl2aj
Mar 29 2018 16:03

Worse than that - most galvanized steel columns are installed with a tough plastic coating on them to extend the life of the buried steel-work so are isolated from the mass of earth.
   

Blazesto
Mar 29 2018 18:45


AlecK
Mar 29 2018 15:45


which might be ok; except that \"stret light pole\" is NOT included on the list of acceptable earth electrodes for an installation.

It might not be on a list but it is accepted by the EWRB, common practice and they have given installers of road lighting, networks and councils dispensation to use it as a main earth.

   

pluto
Mar 29 2018 20:22

Blazesto Mar 29 2018 18:45

Your comment (part only)
It might not be on a list but it is accepted by the EWRB, common practice and they have given installers of road lighting, networks and councils dispensation to use it as a main earth.

My comment
A earth electrodes permitted by law in NZ are described by Electricity (Safety) Regulations 2010 or by a standard (typically AS/NZS 3000) called by the regulations. These regulations are controlled by Energy Safety Service of WorkSafe NZ.

EWRB is mandated to control the registration of electrical workers only, it is NOT the technical agency controlling the use (or provide technical rulings) on the Electricity (safety) Regulations. So I would discount any technical ruling provided by EWRB.
   

Blazesto
Mar 30 2018 08:48

We and everyone else in the country use the pole as the electrode
We have had Sparky\'s audited several times and always passed.

But keep telling me about how you know best.
   

pluto
Mar 30 2018 09:15

There are at least 2 other posters who support that metallic street light poles, with a plastic coating on the base part that is buried in the ground, we all say that a plastic coated pole base will NOT have a satisfactory contact with the mass of earth.

I would refer you AS/NZS 3000 section 5 Table 5.2 for the description of acceptable earth electrodes.

As AS/NZS 3000 and the Electrical (safety) Regulations 2010 have no electrical performance testing of earth electrocdes, the Electricity (safety) Regulations 2010 uses these written descriptions of acceptable electrodes to have a \"deemed to comply\" status in respect to complaince.

Noting that metallic street light poles do NOT fit any of acceptable earth electrodes descriptions, if follows that a metallic street light pole can and should NOT be used for compliance purposes.
   

AlecK
Mar 30 2018 12:23

Or at least, not when the streetlights are installed as an installation.


   

Blazesto
Mar 30 2018 17:51

They do get used and they are perfectly legal. Maybe stick to your own industry.
   

Sarmajor
Apr 02 2018 12:54

Might be legal in Works but definitely not legal in an installation despite what you say the EWRB has allowed. They do not have any authority to vary the regulations or standards. There role is limited to licensing and competency.

If the light pole is installed as an installation then the only acceptable earth electrodes are as detailed in AS/NZS3000:2007 section 5.

And before you tell me to stick to my industry I have worked both sides of the fence and seen most things done right and wrong.
   

zl2aj
Apr 03 2018 08:27

Using the column as an earthing electrode is not considered acceptable in any of the distribution companies I have worked for or with for the above mentioned reasons. It might have been in the past as a method of minimising EPR or voltage rise but certainly not any more.

The point about EWRB not being the technical authority is interesting - why are they conducting audits then? (Rhetorical question - sort of).
   

AlecK
Apr 03 2018 09:59

EWRB\'s job is the licencing and competence of electrical workers.
If they didn\'t conduct some form of audit, how could they know whether we are in fact competent? Or rather, since there\'s plenty of anecdotal evidence that many are not competent; which ones are competent, and which parts of industry might benefit from further education.
   

ppaw1965
Apr 03 2018 15:11

Years ago in West Aussie street lights up poles used to ( and probably still do) have the N connected to the frame to create a fault path for the protection as there’s no effective earth up a wooden or concrete pole. I’ve also been told it’s normal practice on a remote meter board to connect the N to frame for the same reason. Example a stand alone metal meter box at the front of a property. Would the street light poles (stand alone metal ones) be following the same philosophy. I understand these days over there they often use RCDs on strings of these sort of street lights? Or is this something done there and not here? I’ve never worked on any of these systems but have seen and heard bits and pieces over the years.
   

Sarmajor
Apr 03 2018 20:01

That method of earthing metal meter boxes was in the draft version of AS/NZS3000:2016 along with a couple of others.
   

zl2aj
Apr 04 2018 08:05

TNC Earthing (whete the neutral is the earthing conductor) is the system of earthing used before the main switchboard. It can be used for streetlights if the streetlight is not classed as an electrical installation. However the difficulty is demarcation of ownership, and ensuring that safety to the public is maintained. This method is often used for poletop lights however for columns many networks treat them as installation. This is to delineate them from the networks public safety obligations - the scope of which exclude electrical installations and assets owned by others.

In short networks are using this as a means to clearly exclude such assets from their PSMS and future maintenance obligations - probably unnecessarily.

If TNC earthing is allowed in columns you must be able to show that step and touch voltages are maintained within safe limits during normal and abnormal conditions IAW AS/NZS 60479 (ref Energy Safety newsletter May 2016)

Relevent section copied below.

Guidance Note – Electricity supply to street lighting


Issue
Industry has asked for clarification of the acceptability of street lighting being supplied from the electricity supply network without a driven earth and earth/neutral (MEN) link. That is, without the establishment of an ‘installation’.

Comment
The Electrical (Safety) Regulations 2010 are structured principally around risk and the ability to achieve electrical safety. They provide guidance on how the safety of electrical equipment can be achieved and set prescriptive requirements where considered necessary.
With regards to street lighting, no specific requirements have been prescribed, nor is there any restriction to connecting an appliance directly to a distribution system without the need for there to be an installation.
Response
The electricity reticulation network in New Zealand uses the system internationally referred to as a TNC system (the typical power distribution system in New Zealand) , in which the neutral conductor is earthed at regular intervals to ensure that it remains at, or near, earth potential during both normal operation and under fault conditions.
The Regulations do not prevent an arrangement being used in which the ‘neutral’ conductor is used for ‘earthing’ purposes provided that:
• the electrical system supplying the light fittings and the configuration of the lighting system ensures that the earth potential rise (EPR) remains within safe levels as described in IEC 60479 – Effects of current on human beings and livestock (Regulation 8 (2)), and
• the installation configuration meets with the rules associated with the use of a TNC system.
There is no mandatory requirement for a TNC-S (commonly known as MEN) to be established for a supply directly to appliances, such as street lighting.

   

AlecK
Apr 04 2018 08:20

There\'s also the possibility of streetlights being installed as an installation to Part 1 of 3000, in which case the limitation on type of earth electrode would not apply. However documentation would be needed to show how the installation was no less safe than an installation complying with Part 2.