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Posted By Topic: Compliant or Not

Sarmajor
Feb 01 2016 22:32

I have been asked to inspect and connect an installation that is supplied from a pole mounted 15kva transformer via 25m of 1c N/S cable down from the transformer to a metering station.
From there, there is 350 of 16mm bare (existing old) aerial conductors strung on 4 poles before transitioning to 35m of 35mm N/S cable down the last pole into the dwelling.

Our network engineers have calculated the voltage drop in the Mains (from the transformer fusing to the Main Switchboard) at about 12% @ 30 amps.
Gencalc supports this figure.

I believe that the electrician has decided that the mains stop at the metering enclosure and anything after that is sub mains. I disagree with that.
The mains go from the transformer fuses to the MEN switchboard closest to the point of supply. A metering station is not an MEN Switchboard.

Not that this removes the voltage drop from the equation.

I have indicated that I would not be prepared to issue a Pass ROI for this installation on the basis that the voltage drop in the mains (and submains if that is what they want to call them) @ 30 amps would exceed the 5% allowable.

What is the opinion of the collective brain.
   

DougP
Feb 01 2016 23:10

You don't need opinions when you have rules.

1. Mains, run between the point of supply and the main switchboard. A meter location is not a main switchboard.

2. Wiring systems must be installed to satisfy current-carrying capacity, voltage drop and other minimum size requirements for conductors.

3. The cross-sectional area of every current-carrying conductor shall be such that the voltage drop between the point of supply and any point in that electrical installation does not exceed 5% of the nominal voltage at the point of supply.

Besides all that, I'm pretty sure the customer will have problems with the supply voltage only being around 205-215V at times. As well as noticing the large fluctuations in voltage at relativity low loads.
   

Sarmajor
Feb 01 2016 23:31

Doug, I agree completely with your points.
My thoughts were along these lines.
1. The installation fails the 5% volt drop rule. Reg 59 requires domestic installations to comply with AS/NZS3000 Part 2. Section 3.6.2 set 5% as the maximum volt drop between point of supply and any point in the installation.
2. Having failed the volt drop rule the installation mains will most likely fail the EFLI requirement as well.

So despite the electrician presenting a COC stating that all is well it is not. Should be an interesting battle.
   

Power
Feb 02 2016 02:34

At what point do the overhead conductor/s enter the property boundary?


If it is the total distance you have indicated then the volt drop across the consumer mains is non compliant.

If it is from a point anywhere less than that distance then the installation volt drop needs to be taken from that point only - if it is within limits then no problem in issuing a pass.

In the second scenario above the volt drop issue becomes a network problem, the network has a responsibility (as per ESR 28) to supply a voltage within 6% of standard low voltage.
   

Power
Feb 02 2016 02:50

And I should add 5% is not always the allowable volt drop, 7% and 11% have their places too.

To make this interesting:
Would you consider a power pole which supports a transformer a structure?

If yes then the transformer and pole fit the description of 'substation' (ESR definitions of substation) which if inside the property boundary and is there solely for the installation allows the voltage drop to be increased to 7%.

Not that I agree with the above, and not that this value is anywhere near the 12% mentioned...Just a point of discussion.
   

pluto
Feb 02 2016 07:31

The 5% volt drop starts at the point of supply (aa defined by ESR 2010) and goes to the most remote point of the electrical installation, and that includes all the voltage drop in the final sub circuits in the electrical installation.

Someone proposed a 7% volt drop (from AS/NZS 3000) this concession is only for installations when the defined point of supply is very close to the transformer terminals, typically less than about 5 metres, as the additional 2% takes in the volt drop of the distribution system if it was a considerable distance in length, e.g. 10's of metres of distribution line.


This is a another case of someone not doing the correct voltage drop calculations and getting the right result and then installing the electrical installation to that correct design. So a reject is quite in order in my view.
   

Andrew
Feb 02 2016 10:13

There shouldn't be much of a battle just because the CoC wrongly claims the installation is compliant. The whole idea of independent inspection is because electricians make mistakes and a second look is required to ensure things are ok for high risk items like mains work.

In this case the argument about where the mains ends makes no difference to compliance, but does affect whether it needs inspected. If they've actually made the meter board the MSB then you could issue a passing ROI and report the non-compliant downstream work, but either way the installation needs work and the electrician should accept that and make the necessary changes.


   

Sarmajor
Feb 02 2016 11:05

The transformer and supply fuses are at the boundary. The transformer is not exclusively for this customer so 7% is not available.
11% is only available for standalone systems which this is not.

The problem with issuing a pass ROI and connecting the system is that I am required to make a declaration that the work on the installation is done in accordance with the Regulations and is electrically safe.

The installation as it stands is not compliant with the regulations and I know it and our network design department knows it. It may also be electrically unsafe (at least for voltage sensitive equipment).
   

wireman
Feb 02 2016 14:30

On phone, short version.

Does installation fall within Reg 59? It says ..must be...inspected.. in accordance with part 2 of asnzs 3000.

Section 8 under visual has mains requirements that they be suitable for ccc and volt drop among others.

If you're looking for black and white to quote it is there..
   

AlecK
Feb 02 2016 15:27


The mains - which exted nfrom POS to main switch on MSB for A(s) and to ME point at MSB for N)is clearly non-compliant.
The rest of the installation probably is as well, but that's not your official concern because you are only there to look at the compliance or otherwise of the High Risk PEW. Though you also have a separate obligation to report immediate hazards discovered in course of doing PEW ; and you have the option of reporting non-compliant PEW to either ES, EWRB, or both. But you can't get into trouble for not noticing a non-compliance issue that does not affect High Risk PEW.

So as far as inspection of HRPEW goes you have 2 options.
You can issue a "fail" Roi, or you can declare that our inspection is as yet incomplete and so issue no RoI (yet).

Issuing a "fail" roI means the job ("inspect mains") that you contracted to do is complete, so you can send an invoice.

Deciding the inspection is incomplete means you haven't fully performed as per contract so you can't ask for payment (unless you've pre-arranged progress payment terms).

BUT our illustrious regulators' database has NO facility to record whether the inspection resulted in a "pass" (is compliant and will be safe) or a "fail" (is not compliant and/or will not be safe).
Nor will the linesman be likely to read the fine print to see what the RoI actually says, they just want to "sight" a CoC & an RoI (and many don't even wait for those, just hook 'er up and sod off to next job).
   

Sarmajor
Feb 02 2016 17:39

Fortunately for me the job is still in the quotation stage at our end of things and we haven't agreed to connect their installation to the network.
The information presented above is their first (I think) attempt at solving the problem.

Our design department will I am sure offer them a compliant solution based on under grounding the whole cable run in aluminium single cores, probably 2 phase.

Luckily I will be both the inspector and the connector and should notice the fail ROI before acting.

I see that there have been some changes to the eghrd lately, but as you say still no place to record a fail ROI.