AS/NZS 3012:2.9 (d) requires socket outlets installed on the outside of a transportable structure to have the outlet protected by an RCD but the exceptions for that clause say " not if supplying other transportable structures...."
This scenario is often used on construction sites but what is to stop someone using the socket outlet not to connect other sheds but for some other reason, there would be no protection-cant stop fools!
The installs I have seen also wire the out going outlet from the live side of the Main RCBO so that if the first shed is turned off it doesn't turn the power off to the down stream sheds, so I assume this is correct?
Does the earthing of the inlet and outlet need to be joined together as per AS/NZS3001 3.5.1.1, I think this applies to my situation, if so would you join the earths in the same lug on the earth bar (if there is one) or loop the earths at the inlet/outlet?
Transportable Structures supplying power to other structures
Re: Transportable Structures supplying power to other structures
first part of 2.9 says must comply with '3001 "and' the following
which means that all the following are additional to, not instead of ,the provisions of "3001".
Exception (B) allows ACS type systems (with pass-through submains)
which appears to be there just in case someone decides that an ACS unit is within definition of transportable structure.
Exception (A) is limited to where the TS is set up to closely resemble an ACS system; with the socket for 'onward supply" being not on a final subcircuit, but instead directly connected to the inlet / supply lead. In effect, this creates a "submain" type arrangement.
Note there's no requirement in "3000" for equivalent of a "main switch" on a TS (this is set to change in next edition).
As a socket intended for connection of another TS, it must comply with 2.3; which limits the type & rating.
It's not going to be a standard 10 A "3112" socket; instead will almost certainly be am IEC 60309, minimum 16 A.
Otherwise the next TS couldn't plug into it .
This 'pass-through' type arrangement isn't explicitly covered in '3001"; but it's not forbidden (yet).
It's really limited to construction sites; and my understanding is that it was developed particularly for those States in Oz that don't permit ACS systems.
Lack of on-board RCD protection for a 'pass-through" socket isn't a big safety issue;
because the first TS in the line is plugged into a socket on construction wiring ,
- and the socket it plugs into has RCD protection.
For earthing, simplest is always best.
You don't want some fool disconnecting the earth of the pass-through when working at the switchboard.
So of your incoming PEC comes to a swbd, I'd connect the outgoing PEC for a 'pass-through" socket in same terminal,.
Even better, crimp "in" & "out" together; so that there's no chance of it being inadvertently disconnected.
But would be equally compliant , and arguably better practice, for the pass-through to be taken directly from the inlet and not go via the swbd.
Obviously any such system should be well labelled.
3.5.5.1 requires a direct connection between inlet(s) and earth terminal of permanent connection point(s)
which means that all the following are additional to, not instead of ,the provisions of "3001".
Exception (B) allows ACS type systems (with pass-through submains)
which appears to be there just in case someone decides that an ACS unit is within definition of transportable structure.
Exception (A) is limited to where the TS is set up to closely resemble an ACS system; with the socket for 'onward supply" being not on a final subcircuit, but instead directly connected to the inlet / supply lead. In effect, this creates a "submain" type arrangement.
Note there's no requirement in "3000" for equivalent of a "main switch" on a TS (this is set to change in next edition).
As a socket intended for connection of another TS, it must comply with 2.3; which limits the type & rating.
It's not going to be a standard 10 A "3112" socket; instead will almost certainly be am IEC 60309, minimum 16 A.
Otherwise the next TS couldn't plug into it .
This 'pass-through' type arrangement isn't explicitly covered in '3001"; but it's not forbidden (yet).
It's really limited to construction sites; and my understanding is that it was developed particularly for those States in Oz that don't permit ACS systems.
Lack of on-board RCD protection for a 'pass-through" socket isn't a big safety issue;
because the first TS in the line is plugged into a socket on construction wiring ,
- and the socket it plugs into has RCD protection.
For earthing, simplest is always best.
You don't want some fool disconnecting the earth of the pass-through when working at the switchboard.
So of your incoming PEC comes to a swbd, I'd connect the outgoing PEC for a 'pass-through" socket in same terminal,.
Even better, crimp "in" & "out" together; so that there's no chance of it being inadvertently disconnected.
But would be equally compliant , and arguably better practice, for the pass-through to be taken directly from the inlet and not go via the swbd.
Obviously any such system should be well labelled.
3.5.5.1 requires a direct connection between inlet(s) and earth terminal of permanent connection point(s)
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Re: Transportable Structures supplying power to other structures
Giving this more thought the cascading/plug and play system is a rubbish system that opens the installation up for many errors, when any site shed can be connected to the arrangement by a layman, you could possibly end up with 10 sheds cascading off one socket outlet, overloading could be an issue but also the operating of the RCBO's but a layman would know or be concerned about that.
As the interconnecting cables are like a ACS assembly, so are called submains, for compliance of 3001 C7.5, I assume we call the supply lead to TS the incoming lead, the other leads upstream of the supply lead are submains?
What I am trying to say is for C7.5 we dont need to test the earth resistance of all the submains, only the incoming lead to that TS concerned?
3012: 2.9 (b) says max length of supply lead 15m, so once again only the incoming lead not all the submains.
3012 Appendix K5.3 say the devices for interconnection shall have a min rating of 32A, once again TS with the incorrect inlets/outlets could be connected.
All of the above probably only is relevant if we call this system an ACS, as has been mentioned above.
Just doesn't seem correct to me this set up with TS
Sorry all about blurb
As the interconnecting cables are like a ACS assembly, so are called submains, for compliance of 3001 C7.5, I assume we call the supply lead to TS the incoming lead, the other leads upstream of the supply lead are submains?
What I am trying to say is for C7.5 we dont need to test the earth resistance of all the submains, only the incoming lead to that TS concerned?
3012: 2.9 (b) says max length of supply lead 15m, so once again only the incoming lead not all the submains.
3012 Appendix K5.3 say the devices for interconnection shall have a min rating of 32A, once again TS with the incorrect inlets/outlets could be connected.
All of the above probably only is relevant if we call this system an ACS, as has been mentioned above.
Just doesn't seem correct to me this set up with TS
Sorry all about blurb
Re: Transportable Structures supplying power to other structures
Have raised this with NZ working group for revising "3001".
Initial discussion suggests combination of '3012", "3001" & ESRs means that a straight pass-through set-up is non-compliant
and can't be issued with WoEF.
Initial discussion suggests combination of '3012", "3001" & ESRs means that a straight pass-through set-up is non-compliant
and can't be issued with WoEF.
Re: Transportable Structures supplying power to other structures
Wow, there is so many of these set ups out on construction sites, so as they come up for renewal they will be failed then?
If so, this info would possibly not be known by others. Big issue I think
If so, this info would possibly not be known by others. Big issue I think
Re: Transportable Structures supplying power to other structures
Agree
Very complex with 2 different standards, plus ESRs.
Part of the complexity is that as soon as there are 2 or more sockets on the building site that are intended to supply connectable installations, they become a 'caravan park" (both under Standards, and again under ESRs).
Clearly intent of 3012 was to allow a cascade system , with some limits to ensure safety.
But the writers don't appear to have fully understood the "3001 requirements;
which I believe have changed since the concept was first introduced.
I'll need time to work through it carefully.
Question: have you seen any that don't have current limitation for the supply fittings?
That would be a "fail" for WoEF (unless they were old caravan still with a N-E link).
Very complex with 2 different standards, plus ESRs.
Part of the complexity is that as soon as there are 2 or more sockets on the building site that are intended to supply connectable installations, they become a 'caravan park" (both under Standards, and again under ESRs).
Clearly intent of 3012 was to allow a cascade system , with some limits to ensure safety.
But the writers don't appear to have fully understood the "3001 requirements;
which I believe have changed since the concept was first introduced.
I'll need time to work through it carefully.
Question: have you seen any that don't have current limitation for the supply fittings?
That would be a "fail" for WoEF (unless they were old caravan still with a N-E link).
Re: Transportable Structures supplying power to other structures
In answer to your question the three TS's the other day had RCD's not RCBO's
I have also asked around and the feedback I am getting is not compliant and not good practice if it was a compliant.
Just found out these TS's are manufactured in Palmerston Nth, and wired by a local electrical company, so must be lots out there.
I have also asked around and the feedback I am getting is not compliant and not good practice if it was a compliant.
Just found out these TS's are manufactured in Palmerston Nth, and wired by a local electrical company, so must be lots out there.
Re: Transportable Structures supplying power to other structures
Alec, just trying to get it clear in my head, that two or more sockets outlets supplying power to CI's on a construction site make this a caravan park, I know that is the definition in the Regs and 3001, surely a construction site (definition in 3012) is different to a caravan park. In 3012, under 2.3 for switchboards I cant see any restrictions of the number of socket outlets supplying TS's and I know the site supplies need to comply with 3001 also. 3001 2.3 doesn't mention about the number of socket outlets supplying TS's also.
I have seen construction site switchboards with multiple socket outlets supplying TS's and I am sure that these swbs will not be set up to the 3001 in regards to a min 16mm earth, I know that this doesn't make the installation of them correct either.
As I have already mention just trying to clarify things as I am getting lots of questions regarding why or why not the construction switchboards and TS's set ups could be wrong, I am also hoping that I am not the only person looking for your answers on this subject.
I have seen construction site switchboards with multiple socket outlets supplying TS's and I am sure that these swbs will not be set up to the 3001 in regards to a min 16mm earth, I know that this doesn't make the installation of them correct either.
As I have already mention just trying to clarify things as I am getting lots of questions regarding why or why not the construction switchboards and TS's set ups could be wrong, I am also hoping that I am not the only person looking for your answers on this subject.
Re: Transportable Structures supplying power to other structures
Yes this isn't widely understood, so construction sites generally don't comply with 3001 WRT supplies for TSs (both here & in Oz).
Agree it's a bit weird to apply full "caravan park" rules, including depth of burial, etc; and may not have been the intent.
And will be more so when new requirements for earthing of "service pillars" come in (next edition).
But WRT overcurrent protection, RCD, etc for sockets supplying TSs; I believe same or closely similar requirements should apply.
Remember 3001 also has less-strict rules for supplies to TSs at 'other locations'; and entirely understandable of people apply those for construction sites instead instead of "caravan park".
Because of the definition these only officially apply for single sockets (eg at home); and as soon as there are 2 or more sockets it's a 'caravan park" and must comply as such via ESR 60.
It might be reasonable to apply these slightly relaxed rules (which don't include anything about submains or earthing) to construction sites
Except that there are large / remote sites (especially in Oz), where worker accommodation is provided by TSs (they call them "dongas").
Seems to me these should comply with same rules as a 'caravan park".
So a big part of the problem is using the term 'caravan park" for situations most people would not describe that way.
I believe that leads to widespread confusion & misunderstanding.
'3001" definition could be changed; eg so that "caravan park" rules only applied where caravans & mobile homes are expected to be plugged in.
But ESR definition would remain.
So 2 or more sockets on a construction site intended / used for supply to TSs become a "caravan park";
and so must comply with "3001". They may not be a 'service pillar" as defined, which will affect how come of the rules apply.
(They don't have to comply with "3012' because ESRs do not require compliance [ESR 25)
Leaving that mess aside for a while, and just considering a TS (connectable installation) with a "pass-through" socket intended for cascaded connection of other TSs.
The outgoing socket is a socket intended for supply to a TS.
But it isn't part of the construction site installation , so doesn't get counted towards the tally for determining whether 'caravan park" .
Assuming only one; can apply the 'other locations" rules of "3001" - but don't have to.
More confusion & lack of certainty!
It's definitely part of a 'connectable installation" and must comply with "3001";
And must have WoEF before being plugged in
The pass-through socket can be treated as not being on a 'final subcircuit', but more like a "submain"
(which is how "3012" treats ACS pass-throughs; and seems to be the intent of the provisions in '3012').
So on that basis, arguably no RCD required.
But not OK to take the supply directly from inlet; as there must be overcurrent protection for the supply fittings (max demand limitation).
So there has to be at least an mcb in the pass-through wiring, that controls / protects the outgoing socket as well as all the wiring within the TS.
At this stage, and among all the grey areas & complexity, that's one issue I'm certain of; that if current limitation is not in place, then it's non-compliant both for initial certification and for WoEF.
Agree it's a bit weird to apply full "caravan park" rules, including depth of burial, etc; and may not have been the intent.
And will be more so when new requirements for earthing of "service pillars" come in (next edition).
But WRT overcurrent protection, RCD, etc for sockets supplying TSs; I believe same or closely similar requirements should apply.
Remember 3001 also has less-strict rules for supplies to TSs at 'other locations'; and entirely understandable of people apply those for construction sites instead instead of "caravan park".
Because of the definition these only officially apply for single sockets (eg at home); and as soon as there are 2 or more sockets it's a 'caravan park" and must comply as such via ESR 60.
It might be reasonable to apply these slightly relaxed rules (which don't include anything about submains or earthing) to construction sites
Except that there are large / remote sites (especially in Oz), where worker accommodation is provided by TSs (they call them "dongas").
Seems to me these should comply with same rules as a 'caravan park".
So a big part of the problem is using the term 'caravan park" for situations most people would not describe that way.
I believe that leads to widespread confusion & misunderstanding.
'3001" definition could be changed; eg so that "caravan park" rules only applied where caravans & mobile homes are expected to be plugged in.
But ESR definition would remain.
So 2 or more sockets on a construction site intended / used for supply to TSs become a "caravan park";
and so must comply with "3001". They may not be a 'service pillar" as defined, which will affect how come of the rules apply.
(They don't have to comply with "3012' because ESRs do not require compliance [ESR 25)
Leaving that mess aside for a while, and just considering a TS (connectable installation) with a "pass-through" socket intended for cascaded connection of other TSs.
The outgoing socket is a socket intended for supply to a TS.
But it isn't part of the construction site installation , so doesn't get counted towards the tally for determining whether 'caravan park" .
Assuming only one; can apply the 'other locations" rules of "3001" - but don't have to.
More confusion & lack of certainty!
It's definitely part of a 'connectable installation" and must comply with "3001";
And must have WoEF before being plugged in
The pass-through socket can be treated as not being on a 'final subcircuit', but more like a "submain"
(which is how "3012" treats ACS pass-throughs; and seems to be the intent of the provisions in '3012').
So on that basis, arguably no RCD required.
But not OK to take the supply directly from inlet; as there must be overcurrent protection for the supply fittings (max demand limitation).
So there has to be at least an mcb in the pass-through wiring, that controls / protects the outgoing socket as well as all the wiring within the TS.
At this stage, and among all the grey areas & complexity, that's one issue I'm certain of; that if current limitation is not in place, then it's non-compliant both for initial certification and for WoEF.
Re: Transportable Structures supplying power to other structures
Thanks Alec, this is just such a mess! The writers of the standards may know in their heads what they want or mean but unfortunately any readers cant get inside their heads to make sense of things or what was the intent.
Having an OC protection for the pass through wiring for the outgoing socket then means TS1 effectively controls TS2 , and TS2 controls TS3 etc?
Found another clause in 3012 K5.1 detachable submains (interconnecting cables) of an ACS system shall be screened, so standard 3C flex would probably not be acceptable.
In regards to my original setup the contractor is now going to hard wire all the TSs but still worth getting this all to make sense.
Cheers for your help
Having an OC protection for the pass through wiring for the outgoing socket then means TS1 effectively controls TS2 , and TS2 controls TS3 etc?
Found another clause in 3012 K5.1 detachable submains (interconnecting cables) of an ACS system shall be screened, so standard 3C flex would probably not be acceptable.
In regards to my original setup the contractor is now going to hard wire all the TSs but still worth getting this all to make sense.
Cheers for your help
Re: Transportable Structures supplying power to other structures
Cascading is not something I've ever had to deal with directly.
Agree it's a mess, compounded by the way ESRs & Standards inter-relate.
The possible cross-over between ACS (App K of 3012) and connectable installations is another set of issues.
And we also have some 'grey" between whether something is "mobile equipment" or a "connectable installation".
I've discussed the issues arising form clause 2.9 of "3012 with the NZ members of committee for "3001";
who agree there are some issues to be considered; and extra clarity may be needed.
We'll take it to full AS/NZS Committee - but probably too late to do anything in current revision.
But bottom line is less about "does it comply" than "is it safe".
Agree it's a mess, compounded by the way ESRs & Standards inter-relate.
The possible cross-over between ACS (App K of 3012) and connectable installations is another set of issues.
And we also have some 'grey" between whether something is "mobile equipment" or a "connectable installation".
I've discussed the issues arising form clause 2.9 of "3012 with the NZ members of committee for "3001";
who agree there are some issues to be considered; and extra clarity may be needed.
We'll take it to full AS/NZS Committee - but probably too late to do anything in current revision.
But bottom line is less about "does it comply" than "is it safe".
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