Recently assessed an imported yacht for WoEF.
Originally built in USA, so 115 V system; converted by some previous owner for 230 supply.
Basically a nice system; with galvanic isolation by on-board isolating tx.
Tx has dual windings for both primary & secondary; so can be set up in 4 different configurations:
1:1 115 V, 32A; 1:1 230 V, 16 A; step up 115 : 230; or (as used) step down 230: 115.
Shore power using HD lead rated 600V to NEMA Easy Lock connector & inlet fitting (Marinco); inlet fitting clearly labelled 230 V
From inlet 600V rated TPS, via 2P mcb , to tx primary.
Lead - being ex-USA, has black Active and white Neutral, and whoever changed the plug to IEC 60309 type got this wrong, using black for N.
But since the only thing connected is the tx, and the overcurrent protection is in all live conductors, decided polarity wasn't an issue.
Incoming PEC connected to tx core, but not to case.
Case connected to vessel earthing system.
Changed that, because "3004" requires all items required by "3000" to be earthed to be connected to incoming shore PEC.
"3004" allows foreign-built vessels to use non-standard connector & inlet.
However having discovered that shore power active was arriving via white instead of via black, I checked polarity of lead alone
- and found the "rotation" of E-A- N on the connector was anticlockwise instead of clockwise like we use.
Which made me curious; so looked up these fittings on web.
The pins on these fittings are all designed as arcs of a circle, with different widths;
and with some being folded so that they have a "L" section.
There can also be an extra contact on the side of the body.
The "easy-lock" bit is you rotate the plug after insertion into socket (or rotate connector after insertion into inlet)
From what I have now found, seems 125 V 30 A fittings have a folded earth pin with the folded part pointing towards centre of circle.
Other voltages & currents have additional "folded" pins; with some folding away from centre.
In the Marinco handbook; the only 250 V rated fittings are for 2 phase 120 V, with L1 & L2 pins folded away from centre, neutral on 3rd (non-folded) pin, and earth on the side of the body .
So I'm now wondering whether whoever converted the boat just swapped the cover of the inlet; but not the inlet itself.
Which would mean that despite the very clear markings on the inlet that it's 250 V rated; it may only be 125 V rated.
On the other hand; I found a wiring diagram for a 250 V single phase 20 A one here:
https://www.google.com/url?sa=i&url=htt ... Rx6BAgAEAc
The centre image (L6 20 P, L6 30 P) matches what the boat had
Doesn't seem right that 250 V & 125 V fittings would be interchangeable; but there could be size differences in body / pins
Anyone have experience with these things?
Is there a 3-pin 230 / 240 V A,N,E form?
Shore power connector & inlet
Re: Shore power connector & inlet
Alec K
I have for many years worked for an organization that sourced equipment from all parts of the world.
In some cases, it was the only country that made the equipment, so one had to adapt this equipment initially designed for other supply systems to operate in an electrically safe manner on the 230/400 V TNC-S supply available in NZ or AU.
The boat you reported that you were inspecting for a WoEF was reported as being made in the USA.
The usual system of supply used in the USA in domestic and the small industrial is a 2 phase supply (L1 and L2) with a combined earthed centre tap and neutral connection. The system voltages are nominal 115 volts L1 to neutral, L2 to neutral, and the nominal voltage of 230 volts between L1 and L2.
Many high power devices are connected to L1 and L2 (230 Volts). In most cases, the neutral connection is also made to cater for some low power devices within the appliance, which operate from a 115 volt supply only. Hence the plugs and sockets used to connect the appliance to the supply need to have pins and sockets for the L1, L2, N and ground (earth) connections.
A prominent USA manufacturer of socket outlet and plug fittings, Hubbell, website, https://www.hubbell.com/hubbell/en/Prod ... cl/2144290 gives details of the fittings typically used in the USA.
Note this website also gives details of typical isolation transformers used in marine boats to prevent corrosion by PEC earth currents from the TNC-S supply to the water in which the boat is located.
I also note that an international series of fittings are available, which looks like IEC 60309 fittings.
In NZ and AU, using the neutral pin of the USA source sockets and plugs is not practical as to do so could connect 230 volts across an equipment connection designed for supply connection of 115 volts.
Assuming the boat you inspected is not intending to be used other than in NZ or AU. In that case, the non-connection of the inlet plug and cord connector neutrals, and if the isolating TX is permanently connected for 230-volt input, no problem will result from this modification. The NZ or AU connection being L1 connection supply lead Active (phase); L2 connection supply lead Neutral; and Ground (earth) connection supply lead earth.
I note you have reported that you have modified the PEC connected to the TX core; why was this done?
In NZ, this would connect the shore supply PEC to the boat earthing system (including the earthing plate) with the potential to cause corrosion by earth currents from the TNC-S supply to the water in which the boat is located.
Information from the American Boat Yacht Club section E-11 AC and DC ELECTRICAL SYSTEMS ON BOATS clearly shows how the shore supplied PEC to the isolating TX is intended to be connected. The isolation TX has a shield between the primary and secondary windings and an internal transformer case (insulated from the external TX case) which is intended to be connected to the primary winding supply source and protected by the overcurrent device (you need to check suitability for 230-volt operation).
Note also that the Power inlet fittings need to be insulated from the boat.
The following website gives a copy of ABYC website section E-11; http://www.elettronavigare.it/files/E-1 ... ricane.pdf
You should carefully re-consider the modification that you have made and revert to the original earthing connections and use the onboard isolating transformer in the manner it was intended to be used. AS/NZS 3004.2:2008 figure B4 details the connections required.
An alternative would be to use the optional galvanic isolator to prevent earth currents from the TNC-S supply to the water in which the boat is located. The transformer would require no additional hardware to make it compliant with AS/NZS 3004.2.
I was a member of the AS/NZS 3004:2002 drafting committee. I can well remember the long debate that ensued on the subject of the direct connection of the shore supply PEC to the boat earthing system to cause corrosion by earth currents from the TNC-S supply to the water the boat is located. I'm sure that nothing has changed since that time.
I have for many years worked for an organization that sourced equipment from all parts of the world.
In some cases, it was the only country that made the equipment, so one had to adapt this equipment initially designed for other supply systems to operate in an electrically safe manner on the 230/400 V TNC-S supply available in NZ or AU.
The boat you reported that you were inspecting for a WoEF was reported as being made in the USA.
The usual system of supply used in the USA in domestic and the small industrial is a 2 phase supply (L1 and L2) with a combined earthed centre tap and neutral connection. The system voltages are nominal 115 volts L1 to neutral, L2 to neutral, and the nominal voltage of 230 volts between L1 and L2.
Many high power devices are connected to L1 and L2 (230 Volts). In most cases, the neutral connection is also made to cater for some low power devices within the appliance, which operate from a 115 volt supply only. Hence the plugs and sockets used to connect the appliance to the supply need to have pins and sockets for the L1, L2, N and ground (earth) connections.
A prominent USA manufacturer of socket outlet and plug fittings, Hubbell, website, https://www.hubbell.com/hubbell/en/Prod ... cl/2144290 gives details of the fittings typically used in the USA.
Note this website also gives details of typical isolation transformers used in marine boats to prevent corrosion by PEC earth currents from the TNC-S supply to the water in which the boat is located.
I also note that an international series of fittings are available, which looks like IEC 60309 fittings.
In NZ and AU, using the neutral pin of the USA source sockets and plugs is not practical as to do so could connect 230 volts across an equipment connection designed for supply connection of 115 volts.
Assuming the boat you inspected is not intending to be used other than in NZ or AU. In that case, the non-connection of the inlet plug and cord connector neutrals, and if the isolating TX is permanently connected for 230-volt input, no problem will result from this modification. The NZ or AU connection being L1 connection supply lead Active (phase); L2 connection supply lead Neutral; and Ground (earth) connection supply lead earth.
I note you have reported that you have modified the PEC connected to the TX core; why was this done?
In NZ, this would connect the shore supply PEC to the boat earthing system (including the earthing plate) with the potential to cause corrosion by earth currents from the TNC-S supply to the water in which the boat is located.
Information from the American Boat Yacht Club section E-11 AC and DC ELECTRICAL SYSTEMS ON BOATS clearly shows how the shore supplied PEC to the isolating TX is intended to be connected. The isolation TX has a shield between the primary and secondary windings and an internal transformer case (insulated from the external TX case) which is intended to be connected to the primary winding supply source and protected by the overcurrent device (you need to check suitability for 230-volt operation).
Note also that the Power inlet fittings need to be insulated from the boat.
The following website gives a copy of ABYC website section E-11; http://www.elettronavigare.it/files/E-1 ... ricane.pdf
You should carefully re-consider the modification that you have made and revert to the original earthing connections and use the onboard isolating transformer in the manner it was intended to be used. AS/NZS 3004.2:2008 figure B4 details the connections required.
An alternative would be to use the optional galvanic isolator to prevent earth currents from the TNC-S supply to the water in which the boat is located. The transformer would require no additional hardware to make it compliant with AS/NZS 3004.2.
I was a member of the AS/NZS 3004:2002 drafting committee. I can well remember the long debate that ensued on the subject of the direct connection of the shore supply PEC to the boat earthing system to cause corrosion by earth currents from the TNC-S supply to the water the boat is located. I'm sure that nothing has changed since that time.
Re: Shore power connector & inlet
Thanks for your response; and the link.
"3004" is clear that every item required by "3000" to be earthed must be connected to the shore power earthing system.
That must include the case of the transformer used to provide (galvanic) isolation.
Failing to make the change
Contrary to your suggestion; that doesn't connect the boats "earthing" system to the shore power.
the boat's earthing system remains separate, and is tied to one side of the tx output to provide a polarised single-phase supply that has no connection to shore power.
Fig B4 shows an optional galvanic isolator between the boat's earthing system and the incoming shore-power earth;
but it does not show any other connection to the shore power earth at all .
This is consistent with Fig A2 of IEC 60092-507 - the only difference being the IEC Fig doesn't include the galvanic isolator.
Hardly surprising, since a tx provides better galvanic isolation anyway - given that a GI can only prevent galvanic levels of current, with max voltage in order of 1.2 V.
None of these Figs shows the earthing of the tx; either for tx shore-mounted or on-board mounted.
The saftey aspects are identical for both cases; and clearly the case should be earthed to the incoming supply rather than the separate system aboard (regardless of whether the boat's system is 230 V or 115 V).
Just as for an isolating tx used to provide a separated supply, the case of the tx must be earthed to the incoming supply.
Otherwise, for an earth fault on the primary side; the shore power protection device cannot operate reliably to provide the required fault protection.
There's no change to any of this in 2014 edition.
So I'm perfectly happy with the earthing arrangements.
My only concern is the possibility of the cover of the inlet possibly being changed while leaving the "innards" as the original 115 V.
Info available on the web suggests that there are 250 V rated connectors / plugs/ inlets if the same pin configuration that Marinco use for 115 V
"3004" is clear that every item required by "3000" to be earthed must be connected to the shore power earthing system.
That must include the case of the transformer used to provide (galvanic) isolation.
Failing to make the change
Contrary to your suggestion; that doesn't connect the boats "earthing" system to the shore power.
the boat's earthing system remains separate, and is tied to one side of the tx output to provide a polarised single-phase supply that has no connection to shore power.
Fig B4 shows an optional galvanic isolator between the boat's earthing system and the incoming shore-power earth;
but it does not show any other connection to the shore power earth at all .
This is consistent with Fig A2 of IEC 60092-507 - the only difference being the IEC Fig doesn't include the galvanic isolator.
Hardly surprising, since a tx provides better galvanic isolation anyway - given that a GI can only prevent galvanic levels of current, with max voltage in order of 1.2 V.
None of these Figs shows the earthing of the tx; either for tx shore-mounted or on-board mounted.
The saftey aspects are identical for both cases; and clearly the case should be earthed to the incoming supply rather than the separate system aboard (regardless of whether the boat's system is 230 V or 115 V).
Just as for an isolating tx used to provide a separated supply, the case of the tx must be earthed to the incoming supply.
Otherwise, for an earth fault on the primary side; the shore power protection device cannot operate reliably to provide the required fault protection.
There's no change to any of this in 2014 edition.
So I'm perfectly happy with the earthing arrangements.
My only concern is the possibility of the cover of the inlet possibly being changed while leaving the "innards" as the original 115 V.
Info available on the web suggests that there are 250 V rated connectors / plugs/ inlets if the same pin configuration that Marinco use for 115 V
Re: Shore power connector & inlet
Would suggest that you carefully read as/nzs 3004.2:2008 clause 5.5.6 3rd and 4th paragraphs, if says the opposite to what you claim.
- Rating: 16.67%
Re: Shore power connector & inlet
An isolating transformer with a screen between the primary and secondary windings provides for the return of an earth fault tfrom the primary winding to the screen to return to the supply source and nowhere else, but needs the inlet plug to be insulated from the boat metallic parts earthed by the equipotentially earthing system. Transformers made to the UL specification have 4 kV insulation between windings and can provide for the screen to be brought out for connection to the primary winding supply source.
Re: Shore power connector & inlet
Earthing
Agree the screen will deal with any breakdown within the windings.
In this case the screen was correctly connected to incoming shore power earth.
The case wasn't, but now is.
None of the relevant documents is as clear as they could be on the point of earthing the case of the tx.
But clearly for shore-mounted the case must be connected to earth of shore power.
The applicable rules are in"3000", Clause 5.4.1.1;
and "3004" doesn't alter this underlying requirement to earth the tx case to the incoming supply.
Since there's no difference electrically between having the tx mounted ashore or aboard;
if follows that an on-board tx case must also be earthed to shore power.
And - as you say - exposed conductive parts for any fittings up to the tx must also be earthed to the shore power
and isolated from the boat's earthing system (including from the hull if made of metal that's connected to the boat's earthing system).
Protection against electric shock has to come first;
and protection against galvanic corrosion must not interfere with shock protection.
I note Diagram 5 of the ABYC document shows the case connected to boat's earth.
But it also has the boat's earthing system connected (via GI) to shore power earth;
which means the tx is only providing polarisation, not galvanic isolation.
So not directly applicable.
The one that is directly applicable is diagram 6; where the tx is providing both polarisation and galvanic isolation
- and the case is connected to shore power earth; and not to the boat's earthing system.
The tx is screened from the the boat's system by being in a non-conductive enclosure.
Inlet
The inlet is same config shown in Fig 13 of the ABYC document as 125 V 30 A.
I note that there's no "250 V version shown - but that doesn't mean one isn't made; just that it isn't normal for USA.
And I found a diagram that suggests they do exist.
The inlet was certainly clearly marked 250 V.
So perhaps I'm fretting without good cause.
Overcurrent protection
There was no dedicated overcurrent protection for the cables from tx secondary to a.c. swbd.
And enough mcbs that they could be said to be protected by sum-of-ratings.
For overloads the mcb on the primary side would operate; despite seeing only half the current.
For fault protection they were HD insulated & sheathed; and I suppose the primary mcb would react fast enough as long as it has a magnetic trip.
But I'd have preferred to see a protection device; at least in the Active.
Agree the screen will deal with any breakdown within the windings.
In this case the screen was correctly connected to incoming shore power earth.
The case wasn't, but now is.
None of the relevant documents is as clear as they could be on the point of earthing the case of the tx.
But clearly for shore-mounted the case must be connected to earth of shore power.
The applicable rules are in"3000", Clause 5.4.1.1;
and "3004" doesn't alter this underlying requirement to earth the tx case to the incoming supply.
Since there's no difference electrically between having the tx mounted ashore or aboard;
if follows that an on-board tx case must also be earthed to shore power.
And - as you say - exposed conductive parts for any fittings up to the tx must also be earthed to the shore power
and isolated from the boat's earthing system (including from the hull if made of metal that's connected to the boat's earthing system).
Protection against electric shock has to come first;
and protection against galvanic corrosion must not interfere with shock protection.
I note Diagram 5 of the ABYC document shows the case connected to boat's earth.
But it also has the boat's earthing system connected (via GI) to shore power earth;
which means the tx is only providing polarisation, not galvanic isolation.
So not directly applicable.
The one that is directly applicable is diagram 6; where the tx is providing both polarisation and galvanic isolation
- and the case is connected to shore power earth; and not to the boat's earthing system.
The tx is screened from the the boat's system by being in a non-conductive enclosure.
Inlet
The inlet is same config shown in Fig 13 of the ABYC document as 125 V 30 A.
I note that there's no "250 V version shown - but that doesn't mean one isn't made; just that it isn't normal for USA.
And I found a diagram that suggests they do exist.
The inlet was certainly clearly marked 250 V.
So perhaps I'm fretting without good cause.
Overcurrent protection
There was no dedicated overcurrent protection for the cables from tx secondary to a.c. swbd.
And enough mcbs that they could be said to be protected by sum-of-ratings.
For overloads the mcb on the primary side would operate; despite seeing only half the current.
For fault protection they were HD insulated & sheathed; and I suppose the primary mcb would react fast enough as long as it has a magnetic trip.
But I'd have preferred to see a protection device; at least in the Active.
Re: Shore power connector & inlet
The Nema L6 series is for 230/240V
They aren't interchangeable with L5
https://diy.stackexchange.com/questions ... connect-to
They aren't interchangeable with L5
https://diy.stackexchange.com/questions ... connect-to
Re: Shore power connector & inlet
Oh, and yes, the polarity layout is backwards on US outlets (earth, neutral and "hot" - clockwise), but they consider 240V outlets are two "hot" connections (being usually part of a split phase 180deg domestic connection), so they don't really have a polarity AFAIK.
Usually I find it easier not to try and understand the US system, especially once you get into commercial or industrial supplies which are at higher voltages than "normal" and the way they achieve their standard 115V on those sites - easier to just bash ones head against a wall.
Usually I find it easier not to try and understand the US system, especially once you get into commercial or industrial supplies which are at higher voltages than "normal" and the way they achieve their standard 115V on those sites - easier to just bash ones head against a wall.
Re: Shore power connector & inlet
The image I found showed L6 as 250 V, with very similar pin config to the L5 125 V gear.
Both being "single-phase" 3-pin (2 x live connections + E)
The third one in the image was L14; being 4-pin 2-phase.
Which I presume is the one shown in both Marinco & another manufacturer's info.
No dimensions on the image; but L6 appears to be slightly larger diameter overall,
and possibly "wider" pins arranged on circumference of a bigger circle.
That suggested non-compatibilty-by-size.
More importantly (for me) it suggested the fittings I saw may have been kosher and the label on the lid valid.
So maybe I'm being over-cautious; in reaction to something the owner said he'd been told.
With 250 V rated fittings in the range, I don't have any basis for thinking the insulation and clearances aren't good enough to be electrically safe.
Not many imported boats this part of the country; so may never have another to look at.
But there's a good chance this boat will be back in 4 years time; so want to be more certain
Especially as changing to IEC 60309 would result in an ugly and awkwardly protruding tripping & rope-catching obstruction,
where the existing is all but flush.
Interesting coincidence to find last week a NZ-based mail order supplier was discounting items from Marinco range of fittings,
in particular the 2 male to 1 female and 2 female to 1 male adaptors.
Wouldn't have thought there was much market this side of the Pacific
considering this standard can only be used for the inlet / connector,
and only for boats built overseas.
I presume this was old stock that they have imported without knowing about NZ rules.
Both being "single-phase" 3-pin (2 x live connections + E)
The third one in the image was L14; being 4-pin 2-phase.
Which I presume is the one shown in both Marinco & another manufacturer's info.
No dimensions on the image; but L6 appears to be slightly larger diameter overall,
and possibly "wider" pins arranged on circumference of a bigger circle.
That suggested non-compatibilty-by-size.
More importantly (for me) it suggested the fittings I saw may have been kosher and the label on the lid valid.
So maybe I'm being over-cautious; in reaction to something the owner said he'd been told.
With 250 V rated fittings in the range, I don't have any basis for thinking the insulation and clearances aren't good enough to be electrically safe.
Not many imported boats this part of the country; so may never have another to look at.
But there's a good chance this boat will be back in 4 years time; so want to be more certain
Especially as changing to IEC 60309 would result in an ugly and awkwardly protruding tripping & rope-catching obstruction,
where the existing is all but flush.
Interesting coincidence to find last week a NZ-based mail order supplier was discounting items from Marinco range of fittings,
in particular the 2 male to 1 female and 2 female to 1 male adaptors.
Wouldn't have thought there was much market this side of the Pacific
considering this standard can only be used for the inlet / connector,
and only for boats built overseas.
I presume this was old stock that they have imported without knowing about NZ rules.
Re: Shore power connector & inlet
Hi All
Please Aleck don't alter the earthing as you have done, this will cause galvanic corrosion under certain circumstances and potential hazard from earth fault currents back to shore when connected to shore power under fault conditions . Our surveyor will fail you if wired this way.
see here:
https://www.victronenergy.com/blog/2016 ... -seawater/
Fig 13 relevant
Please Aleck don't alter the earthing as you have done, this will cause galvanic corrosion under certain circumstances and potential hazard from earth fault currents back to shore when connected to shore power under fault conditions . Our surveyor will fail you if wired this way.
see here:
https://www.victronenergy.com/blog/2016 ... -seawater/
Fig 13 relevant
Re: Shore power connector & inlet
Not true
Galvanic isolation by transformer is not in any way dependent of whether the case, or the inter-winding protective shield (if fitted), are connected to shore earth or boat's earth. The only thing that matters for galvanic isolation is that there are no connections between the 2 earthing systems.
ABYC document "E11" shows a number of diagrams, covering both scenarios where the tx is used only for polarisation and six where it also provides galvanic isolation. Of those 6, 3 cover 2-phase supply and the other three cover single-phase supply.
Both sets cover 3 options:
a) case and shield connected to shore earth (diagrams 6 & 9)
b) connected to shore earth & case connected to boat's earth (diagrams 7 & 10)
c) case and shield connected to boat's earth (diagrams 8 & 11)
These are presented as all being equally valid; and there is no guidance provided suggesting any preferences for any particular conditions.
(note: the inter-winding shield is a requirement under this document; and it's also a requirement that the tx case be metallic)
However while that's useful as background, and shows that the earthing connections simply don't matter for purposes of galvanic isolation; it isn't directly relevant because that document applies to the prevailing conditions (voltage, frequency, and supply system) for northern America; whereas NZ's requirements are set in the context of our MEN system of supply.
In particular, the WoEF system has to ensure that boats wired overseas are safe to operate on our supply system, and at our voltage & frequency.
The requirements are set on AS/NZS 3000; as modified by AS/NZS 3004.2 (both being modelled on the equivalent IEC documents; so therefore compatible with international practice).
The earthing of the tx case is about providing fault protection; not about galvanic isolation.
And for fault protection purposes, there are 4 acceptable methods - the most common, being automatic disconnection of supply (as in this case).
That method requires that accessible conductive parts of equipment must be connected to the protective earthing conductor of the circuit that supplies them; in order that a sufficiently high current can flow for the protective device to operate within the required time [refer clause 1.5.5.3].
For any transformer; that's the line side; not the load side.
These connections are not shown in the relevant Figs of the IEC and AS/NZS documents; because practitioners are expected to understand that the the 'special case' Standards amend or modify the underlying rules of the parent Standards; and if they are silent on any matter it just means that no underlying requirement has been modified.
Following the underlying general requirements; the items within the boat that are required to be earthed are always connected together; and where a tx is not used to provide galvanic isolation they are connected to shore earth.
The only modification in "3004.2" is that where the boat is fitted with a transformer to proved galvanic isolation; instead of being connected to the incoming shore supply earth the items downstream of the tx are connected together in an equipotential bonding system; to which the neutral of the tx secondary winding is also connected to provide polarisation.
That has further implications for provision of fault protection; because a small tx may not allow sufficient current to flow to operate protective devices within the specified time limits.
However nothing on "3004.2" allows for the case of the tx to be connected to the boat's earthing system instead of to the shore supply earth.
Coming to the specific WoEF requirements; clause C11.2 's testing requirements include - as the first item - "the connection between any point on the installation required to be earthed and the switchboard earth bar or terminal is continuous".
A metallic tx case is required to be earthed; and it won't comply if it's connected to boats earth instead of the supply side earth.
Galvanic isolation by transformer is not in any way dependent of whether the case, or the inter-winding protective shield (if fitted), are connected to shore earth or boat's earth. The only thing that matters for galvanic isolation is that there are no connections between the 2 earthing systems.
ABYC document "E11" shows a number of diagrams, covering both scenarios where the tx is used only for polarisation and six where it also provides galvanic isolation. Of those 6, 3 cover 2-phase supply and the other three cover single-phase supply.
Both sets cover 3 options:
a) case and shield connected to shore earth (diagrams 6 & 9)
b) connected to shore earth & case connected to boat's earth (diagrams 7 & 10)
c) case and shield connected to boat's earth (diagrams 8 & 11)
These are presented as all being equally valid; and there is no guidance provided suggesting any preferences for any particular conditions.
(note: the inter-winding shield is a requirement under this document; and it's also a requirement that the tx case be metallic)
However while that's useful as background, and shows that the earthing connections simply don't matter for purposes of galvanic isolation; it isn't directly relevant because that document applies to the prevailing conditions (voltage, frequency, and supply system) for northern America; whereas NZ's requirements are set in the context of our MEN system of supply.
In particular, the WoEF system has to ensure that boats wired overseas are safe to operate on our supply system, and at our voltage & frequency.
The requirements are set on AS/NZS 3000; as modified by AS/NZS 3004.2 (both being modelled on the equivalent IEC documents; so therefore compatible with international practice).
The earthing of the tx case is about providing fault protection; not about galvanic isolation.
And for fault protection purposes, there are 4 acceptable methods - the most common, being automatic disconnection of supply (as in this case).
That method requires that accessible conductive parts of equipment must be connected to the protective earthing conductor of the circuit that supplies them; in order that a sufficiently high current can flow for the protective device to operate within the required time [refer clause 1.5.5.3].
For any transformer; that's the line side; not the load side.
These connections are not shown in the relevant Figs of the IEC and AS/NZS documents; because practitioners are expected to understand that the the 'special case' Standards amend or modify the underlying rules of the parent Standards; and if they are silent on any matter it just means that no underlying requirement has been modified.
Following the underlying general requirements; the items within the boat that are required to be earthed are always connected together; and where a tx is not used to provide galvanic isolation they are connected to shore earth.
The only modification in "3004.2" is that where the boat is fitted with a transformer to proved galvanic isolation; instead of being connected to the incoming shore supply earth the items downstream of the tx are connected together in an equipotential bonding system; to which the neutral of the tx secondary winding is also connected to provide polarisation.
That has further implications for provision of fault protection; because a small tx may not allow sufficient current to flow to operate protective devices within the specified time limits.
However nothing on "3004.2" allows for the case of the tx to be connected to the boat's earthing system instead of to the shore supply earth.
Coming to the specific WoEF requirements; clause C11.2 's testing requirements include - as the first item - "the connection between any point on the installation required to be earthed and the switchboard earth bar or terminal is continuous".
A metallic tx case is required to be earthed; and it won't comply if it's connected to boats earth instead of the supply side earth.
Re: Shore power connector & inlet
I would suggest you read AS/NZS 3004.2:2008 clauses 5.5.5 , 5.5.6 and 5.5.7 carefully when carrying out testing of the earthing conenctions required. The clause required to be used depends on the location of the isolating transformer (on the marina, or on board), if none, you use clause 5.5.7. Appendix C testing required needs inproving to cover the use of islating transformers.
See my prevous post on this subject and also that by Camel007 we have the requirements correct.
See my prevous post on this subject and also that by Camel007 we have the requirements correct.
Re: Shore power connector & inlet
Since this boat has an on-board tx; the only relevant clause is 5.5.6.
Neither your post nor Camel007's includes any justification for preferring the tx case be earthed to boat's earthing system';
which is contrary to the underlying requirement of AS/NZS 3000 that it be earthed to the circuit that supplies it.
Neither your post nor Camel007's includes any justification for preferring the tx case be earthed to boat's earthing system';
which is contrary to the underlying requirement of AS/NZS 3000 that it be earthed to the circuit that supplies it.