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Posted By Topic: Solar to distribution board, EL001 committee

OctaneOutlaw
Dec 14 2018 17:32

Hey everyone

Just have a quick question, can anyone tell me where I can find a reference to the second statement to this? Says in 3000 but can't find anything via search

It was a PDF about solar installation and said if solar supply is connected to a distribution board the PEC to that board must be of at least 4mm2

References ruling from EL001 committee and I know some of you are part of that


-update file won't post but hopefully enough info in post-
   

OctaneOutlaw
Dec 14 2018 17:35

It was in a solar PV generation guide by Solar Group so easy to look up if anyone wants a reference to my post
   

AlecK
Dec 15 2018 07:25

Pretty sure not in "3000".
Maybe in "5033"?
   

OctaneOutlaw
Dec 15 2018 08:33

I haven't yet been able to find it in either, maybe I'll try 4777

The exact quote on there PDF is as follows, the second part is the part in question

"The following standards and regulations Apply Within New
Zealand:

AS/NZS 3000 – Wiring Rules

All PV array system bonding conductors shall comply with the material, type, insulation,
Identification; installation and connection requirements specified in AS/NZS 3000 but shall
not have a cross-sectional area less than 4mm².
Reference - AS/NZS 3000:2007 Clause 5.6.3.2

Where the solar supply is connected to a sub-board the protective earth between the main
switchboard and sub-board may be of a cross-sectional area less than 4mm².
Reference – ruling from EL 001 committee - AS/NZS 3000:2007"
   

OctaneOutlaw
Dec 15 2018 08:42

I have noticed it's a PDF dated for 2013 so maybe some of it's outdated but that's why I was checking the references as I went to prove them current but I just couldn't find this one anywhere as of yet
   

AlecK
Dec 15 2018 09:27

Noting that when talking about NZ requirements, the edition of "3000" currently cited is 2007 + A1 + A2.

However 5.6.3.2 remains unchanged in 2018 edition.
This clause sets minimum sizes for equipotential bonding conductors. It does this for three types of things:
a) conductive piping, cable sheaths, and wiring enclosures;
b) showers, bathrooms, swimming & spa pools; and
c)telephone and telecommunications equipment.
Nothing there about PV array bonding; and NO specific minimum size set for non-listed applications.

There may be something in "5033", haven't checked (too busy today but will later); but for reasons below I very much doubt it.

So on the face of it, the statement is untrue. However the reason for the 4 mm2 size set for 2 of the listed applications relates to physical robustness of the single, insulated but unsheathed, conductor typically used for EPB.

The proposition appears to be based on the isda that where an array is bonded to a DB; the DB's submain PEC should be at least as big as the array EPB conductor. That's not necessarily true, and it certainly isn't stated in "3000". It's actually faulty logic. The functions of PEC and EPBC are different. While both are intrended to avoid hazardous touch voltages on accessible conductive parts; PECs are designed to carry very high currents in order that overcurrent devices will operate, and EPBCs are not expected to mcvarry high current but only the low currents that may arise from various parts being at different "earth" potential.

Where an array is bonded to a DB, it's unlikely that anything connected - earthed or bonded- to the MSB's (or any other switchboard's) earthing system will be simultaneously accessible with the PV array. Also, the DB may well be in an outbuilding supplied by a submain that simply doesn't have a PEC. Thus there isn't a sound technical reason to set such a requirement.

Tyhe EL 001 Committee does not issue "rulings". A ruling would be equivalent to a requirement set in a clause, and as such would be required to go through the full process used for amendments - including public consultation. It just does NOT happen. Nearest you'll find is the "FAQs" [ www.wiringrules.standards.org.au ], which are explanations and have equivalent status to Notes to clauses.
Most of the previous FAQs were included into the 2018 edition; so there are now only a few left. If there had been one similar to what they cite; it would have been included as a change to 5.6.3.2.

It may be that they had an opinion from an individual member of the Committee, but such opinions have NO official standing. And in my view this one is simply wrong.




   

pluto
Dec 15 2018 09:29

read AS/NZS 5033:2014 clause 4.4.2.2 this covers earthing of PV arrays.

AS/NZS 5033:2014 is currently not cited by ESR 2010 but the use of a newer edition is permitted as the newer edition will, in general, have aditional requirements to those mandated by the cited edition which is 2012.

I was one of the drafting team for 5033 since 2008.

Another observation the connection of GRID CONNECT inverters to distribution switchboards is not possible due to revenue metering issues. The requirement is to be able to detrimine the power imported and exported from or to the local electricity distributors network.

This requirement is NOT part of AS/NZS 5033, but are requirements of the NZ Electricity Authority rules covering revenue metering.
   

OctaneOutlaw
Dec 15 2018 10:05

Thank you both,very much appreciated
   

OctaneOutlaw
Dec 15 2018 10:32

I just relooked at your comment Pluto

Where would I find these rules? So basically it's not legal to connect to a distribution board? How does this not work with the metering?

Is there anyway around this?
   

pluto
Dec 15 2018 13:52

OctaneOutlaw Dec 15 2018 10:32


Your comment 1
Where would I find these rules?

My comment 1
Use Google and search on "Electricity Authority" and the EA rules on metering are there.

Another source is the 'distributed generation " rules of the Lines company in the area in which you are working in, they should detail the metering arrangements or will refer you to the retailer for the installation.

your comment 2

So basically it's not legal to connect to a distribution board?

How does this not work with the metering?

My comment 2
The metering requirements of the Electricity Authority is that all energy imported into an installation has to be on one meter register and all energy exported from the installation has to be on a second meter register.

The usual requirements for all metering to be at one location (often at the main switchboard location or very near to that position) precludes revenue metering being located on distribution switchboards.

Your comment 3
Is there anyway around this?

My comment 3
No. A submain beck to the main switchbaord is a typical way.
   

pluto
Dec 15 2018 13:55

BTW the joint stsndards committee which deal with PV systems is NOT EL-001, it is EL-042, on which there are only a few NZ committee members I am one of the NZ members.
   

dbuckley
Dec 17 2018 08:57

I think there is a set of misunderstandings between the lines going on here.

The thread started with a question about PECs, and essentially, whether its OK to connect solar up to a sub-board, and the answer appears to be yes one can.

The thread then drifted to revenue meters, and it was pointed out that the revenue meters have to be at the edge of the installation, and thus connect to the main or only switchboard housing the main switch.

The two scenarios are not exclusive; the revenue meters will measure any power exported wherever it is generated within the installation. Though obviously the local generation will first supply all the loads of the installation before the question of export even arises.

Adding the obvious caveat that in all but the most unusual circumstances exporting power is not a cost-effective thing to do, one needs to use every watt generated at the moment of generation, to reduce import as far as possible, and export nothing, a/k/a "zero export".


   

Sarmajor
Dec 17 2018 11:49

Dbuckley, you are correct that the metering will record export power regardless of where it enters the installation, after all it is the surplus after supplying all of the installations connected load.

I have been to many sites that have solar power to supply their connected load and do not have export registers in their meters. A conscious decision based on the poor return on investment for exported power and the fact that the solar installation is insufficient to generate export except in exceptional circumstances.
   

AlecK
Dec 17 2018 12:01

Since the OP was solely about the earthing and bonding of the array; the rules for grid-connected inverters are only of peripheral relevance. It wasn't about WHETHER an array can be connected at a DSB - it can. Nor was it about under what circumstances an inverter was connected at a DB. It was simply about whether the quoted statement relating to earthing and bonding of arrays was correct - which it wasn't.

But; since we've strayed off into other matters...

Wiring Rules, ie "3000" & its "companion" Standards, don't deal with revenue metering requirements or load control. As far as Wiring Rules are concerned, such equipment is simply part of the installation (as "electrical installation" is defined for NZ).

Requirements set by networks for load control, and by retailers for revenue metering; are a separate issue. There's no safety reason for requiring separate registers for import & export; and this NZ requirement is not universal.

Also have to remember that the PV array is a separate issue from the connection of an inverter, and different Standards apply to each. While we now have inverters being built into the arrays, the rules are still in different Standards.

So Wiring rules, including "5033" (PV arrays) & 4777.1 (grid-connected inverters), don't prohibit connecting an array / inverter combination at a DB. And unless it's a grid-connected inverter, nor do the Regulations governing metering. Even for grid-connected, it's not a straightforward prohibition but rather the imposed preference for separate registers that makes it impracticable ; for no sound technical reason; just a commercially driven preference.
   

OctaneOutlaw
Dec 17 2018 13:58

Thank you, this has cleared up the original point and a few other things

I don't know if it was my misunderstanding but what Pluto was saying but I think it's all cleared up now