Probably a stupid question but what is the definition of a private network or makes a private network, I have seen subdivisions in the area I live where they are called "private networks"?
Not sure if the reticulation for the subdivision is metered at the transformer that supplies power to the dwellings but all the houses have Retailer Revenue meters.
I assume "point of supply" comes into it, possibly if the POS's were identified at the Main Switchboards it would make things clearer for electricians and inspectors.
Quite often I hear "its a private network" so that doesn't need inspecting etc but I know the Act and Regs don't make exemptions for Private networks, sometimes mains are not mains but submains but any MEN link or earthing to an electrode still requires inspecting, private network or not.
I have seen retirement villages that have their own transformers and reticulation, so assume that these would be private networks as they are solely for the village use, once again though have Retailers meters installed.
What are the advantages of a private network?
Possibly someone can clarify it for me?
Peter
Private network
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gregmcc
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Re: Private network
Metering has no bearing on this, it is the definition of an installation, where main switchboard is defines the MEN point and the mains back to the point of supply which then defines which part of the installation is high risk work and requires inspection.
Re: Private network
Thanks Greg but how does that explain a private network subdivision which has no Main Switchboard?
Re: Private network
Agree that any "main earthing system" that is installed within an installation is high risk PEW and must be inspected.
Same for installation of "mains".
It's important that:
- only PEW on an "installation" needs to be certified;
- only PEW on an "installation" has a risk classification under ESR 6A;
It follows that only PEW on an "installation" can require inspection.
So the key to whether or not inspection is required is whether the work has been done on "works' or on an "installation".
The definitions of "works" and "installation" are mutually exclusive.
"Works" is defined as any fittings that are used, or designed or intended for use, in or in connection with the generation, conversion, transformation, or conveyance of electricity; but does not include any part of an electrical installation.
(note that ownership is not mentioned; so 'works" is not limited to fittings owned by electricity distributors)
Definition of "electrical installation" states that for any installation that has a POS, the installation commences at the POS.
The alternative of no POS is for off-grid installations.
So yes the POS is important, in fact crucial.
As Greg says, revenue metering has nothing to do with these fundamental definitions.
Nor does the ICP system for uniquely identifying consumers.
'Private network' isn't a defined term; so best not used.
Doesn't matter who owns the fittings in question; all that matters is whether they are part of 'works", or part of an "installation"
And that comes down to establishing where the POS is for the particular installation.
POS definition is complex, to cover a variety of situations.
But in all cases it relates to "a property"; another term defined in clause (3), and always related to land within a legal boundary.
The definition also relies on the concept of "exclusive fittings" (that supply only one property); vs "non-exclusive fittings" that supply more than one property.
POS is straightforward for most cases of a single installation on a property: the point on the boundary where "exclusive fittings" enter the property.
The (network-owned) supply fuse(s) (up pole or in pillar / pit) is "exclusive fittings", but outside the boundary so not the POS.
From the supply fuse(s) & network neutral connection come conductors that are also 'exclusive fittings"; but still outside boundary.
Where these supply conductors cross the boundary is the PoS; and that's where the "installation" begins.
Also the "mains" begins there (there's no defined term for the same conductors upstream of POS, but they are not "mains").
There are 4 exceptions to this default location for POS
a) If tx on the property that's owned by the "electricity distributor": POS is where output from tx enters 'exclusive fittings".
b) If any non-exclusive fittings on property, ; POS is where they become exclusive fittings.
c) If exclusive fittings on property are owned by a tenant, POS is where those EFs enter the tenant's area.
So this allows for there to be multiple separate installations within the property; in which case each must have own MSB etc.
d) POS can be at a point determined by a "specific agreement" (see definition of "specific agreement"
I know that probably doesn't help much.
And while the electricity distributor should be able to state clearly where the POS is; I suspect they get just as confused as we do.
But the way I read it; where distributor's supply fuses are within the property; the POS will generally be the load side of these fuses.
Remember that (nowadays) MENs for installations must be at MSB.
And before it can be the MSB, it has to qualify as a 'switchboard" (as defined in "3000");
which means there must be circuit protection devices for submains and / or final subcircuits.
If the only protective devices are for mains; then it is not a switchboard, so can't be the MSB.
In which case there can't be a MEN connection there, and any switch located there isn't a "main switch".
So having a common distribution / metering point within the property (eg metering point for block of flats / shops) doesn't always mean it's the MSB.
Where there are multiple consumers on a property; they can be configured either
a) as a single installation, with single POS, one set of "mains", and one "main earthing system"; and each consumer supplied from MSB via submains.
b) as a collection of separate installations, each with own POS, mains, MSB & MES .
Under option b), there may well be fittings within the property (upstream of those POSs) that are not owned by the electricity distributor, but by the landlord of the property. That would be private works.
Many high-rise buildings have what's called "rising mains"; with tee-offs to each floor.
But based on definitions these conductors are generally not "mains" at all.
They are either submains of a single installation (which has a single MEN at MSB);
Or they are private works (with each tenancy having a POS on the relevant floor, its own MEN, and its own MEC to an electrode).
Same for installation of "mains".
It's important that:
- only PEW on an "installation" needs to be certified;
- only PEW on an "installation" has a risk classification under ESR 6A;
It follows that only PEW on an "installation" can require inspection.
So the key to whether or not inspection is required is whether the work has been done on "works' or on an "installation".
The definitions of "works" and "installation" are mutually exclusive.
"Works" is defined as any fittings that are used, or designed or intended for use, in or in connection with the generation, conversion, transformation, or conveyance of electricity; but does not include any part of an electrical installation.
(note that ownership is not mentioned; so 'works" is not limited to fittings owned by electricity distributors)
Definition of "electrical installation" states that for any installation that has a POS, the installation commences at the POS.
The alternative of no POS is for off-grid installations.
So yes the POS is important, in fact crucial.
As Greg says, revenue metering has nothing to do with these fundamental definitions.
Nor does the ICP system for uniquely identifying consumers.
'Private network' isn't a defined term; so best not used.
Doesn't matter who owns the fittings in question; all that matters is whether they are part of 'works", or part of an "installation"
And that comes down to establishing where the POS is for the particular installation.
POS definition is complex, to cover a variety of situations.
But in all cases it relates to "a property"; another term defined in clause (3), and always related to land within a legal boundary.
The definition also relies on the concept of "exclusive fittings" (that supply only one property); vs "non-exclusive fittings" that supply more than one property.
POS is straightforward for most cases of a single installation on a property: the point on the boundary where "exclusive fittings" enter the property.
The (network-owned) supply fuse(s) (up pole or in pillar / pit) is "exclusive fittings", but outside the boundary so not the POS.
From the supply fuse(s) & network neutral connection come conductors that are also 'exclusive fittings"; but still outside boundary.
Where these supply conductors cross the boundary is the PoS; and that's where the "installation" begins.
Also the "mains" begins there (there's no defined term for the same conductors upstream of POS, but they are not "mains").
There are 4 exceptions to this default location for POS
a) If tx on the property that's owned by the "electricity distributor": POS is where output from tx enters 'exclusive fittings".
b) If any non-exclusive fittings on property, ; POS is where they become exclusive fittings.
c) If exclusive fittings on property are owned by a tenant, POS is where those EFs enter the tenant's area.
So this allows for there to be multiple separate installations within the property; in which case each must have own MSB etc.
d) POS can be at a point determined by a "specific agreement" (see definition of "specific agreement"
I know that probably doesn't help much.
And while the electricity distributor should be able to state clearly where the POS is; I suspect they get just as confused as we do.
But the way I read it; where distributor's supply fuses are within the property; the POS will generally be the load side of these fuses.
Remember that (nowadays) MENs for installations must be at MSB.
And before it can be the MSB, it has to qualify as a 'switchboard" (as defined in "3000");
which means there must be circuit protection devices for submains and / or final subcircuits.
If the only protective devices are for mains; then it is not a switchboard, so can't be the MSB.
In which case there can't be a MEN connection there, and any switch located there isn't a "main switch".
So having a common distribution / metering point within the property (eg metering point for block of flats / shops) doesn't always mean it's the MSB.
Where there are multiple consumers on a property; they can be configured either
a) as a single installation, with single POS, one set of "mains", and one "main earthing system"; and each consumer supplied from MSB via submains.
b) as a collection of separate installations, each with own POS, mains, MSB & MES .
Under option b), there may well be fittings within the property (upstream of those POSs) that are not owned by the electricity distributor, but by the landlord of the property. That would be private works.
Many high-rise buildings have what's called "rising mains"; with tee-offs to each floor.
But based on definitions these conductors are generally not "mains" at all.
They are either submains of a single installation (which has a single MEN at MSB);
Or they are private works (with each tenancy having a POS on the relevant floor, its own MEN, and its own MEC to an electrode).
Re: Private network
Thanks Alec, the term 'private network" gets used a lot especially by engineers, where as they should say "works/private works"?
So the "private network" of a subdivision is "works" from the LV side of the tx, as the fittings are non-exclusive fittings until they become exclusive fittings to each dwelling (eg at distribution pillar) and then the POS is normally at the boundary of the property, "works" from the pillar to the boundary and "mains" from the boundary to the main switchboard.
Definitely would help if the POS had to be identified somewhere.
So what is the advantage then of a private network/private works?
So the "private network" of a subdivision is "works" from the LV side of the tx, as the fittings are non-exclusive fittings until they become exclusive fittings to each dwelling (eg at distribution pillar) and then the POS is normally at the boundary of the property, "works" from the pillar to the boundary and "mains" from the boundary to the main switchboard.
Definitely would help if the POS had to be identified somewhere.
So what is the advantage then of a private network/private works?
Re: Private network
Unsure as to any particular advantage in context of normal distribution.
Just something that happens in some multi-occupancy properties.
And for subdivisions, the developer may have installed the distribution, but maybe the local electricity distributor declines to accept ownership (and ongoing responsibility for maintenance).
But it will become more of an issue in future; with increasing "distributed generation".
If a single consumer adds a PV & inverter system as "supplementary supply" for their installation, it's all within one installation.
But larger communal systems, spread across several consumer's properties, raise issues.
Just something that happens in some multi-occupancy properties.
And for subdivisions, the developer may have installed the distribution, but maybe the local electricity distributor declines to accept ownership (and ongoing responsibility for maintenance).
But it will become more of an issue in future; with increasing "distributed generation".
If a single consumer adds a PV & inverter system as "supplementary supply" for their installation, it's all within one installation.
But larger communal systems, spread across several consumer's properties, raise issues.
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