Hi, just looking for some help in determining compliance for an installation or advice on configuration.
The property has a meter board on the fence line with earth electrode etc. There were 2 seperate buildings fed from the meter board with their own switchboards and earth electrodes.
Currently a new building is being put up against one of the existing buildings and the other existing building will be butted up to the other side of the new building creating one larger building.
I have a spare cable from the meter board to connect the new section of building as a seperate installation but this cable and the cable for the other buildings are single core NS. It would be very hard to run a PEC from the meter board. Can this building be configured as 3 seperate installations with their own MEN board and electrodes or is it classed as an outbuilding with only 1 MEN board allowed?
Multiple Electrical Installation
Multiple Electrical Installation
You have called this a multiple installation, and it may be that. Equally it could be a collection of separate installations.
The key issue is where is the point of supply (or points of supply).
Remember that metering, occupancies, and similar are not relevant to definitions of installation.
the meter enclosure, c/w electrode, presumably also has an MEN link.
Assuming all one installation with a single PoS; then this will be the MSB.
Therefore must also include the main switch(es).
The 2 x existing structures will be outbuildings, each fed by PEN submain as per 5.5.3.1(b).
Which is acceptable provided they are separate structures; both WRT the structure containing the MSB and WRT each other.
For purposes of Wiring Rules, these are regarded as "separate MEN installations"; and this affects not only the earthing but also main switch requirements.
However for purposes of ESRs they are all part of one large electrical installation (as defined in Electricity Act); which starts at the point of supply (point of supply is also defined in the Act). So as far as ESRs are concerned,
The proposed in-fill structure will change the circumstances, effectively there will be no separation between the 3 'outbuilding" structures, in fact there will be only one structure containing several separately-supplied parts of the installation - in this case,three .
This meets the definition of 'combined outbuilding" (new in 2018 edition); any number of structures , containing more than one supply, and on same foundation or sharing conductive roofing / framing. Under 2018 edition, PEN supply is not permitted for "combined outbuildings".
Currently 2018 edition has not yet been cited, and MBIE has declared intent to have dual-citation with 2007 (though this may change).
So unless / until that citation occurs (and perhaps even afterwards), these "new" rules around supply to "combined outbuildings" are not mandatory.
So it might seem compliant (with 5.5.3.1(b)) to treat the 3 parts as each being a different "outbuilding" . Each of the three "outbuildings" has separation from the structure that contains the MSB; so meets the definition. Each will have only one MEN within it, so 'complies' with item (i).
NOT good practice, because this is exactly what the 2018 edition is trying to prevent; but technically compliant (with 5.5.3.1 (b)).
However this interpretation only works if you can, hand-on-heart, say there are 3 structures rather than one.
5.5.3.1(b) is not the only consideration, and there are other rules that also apply.
Under both ESRs and Wiring rules, what happened earlier isn't directly relevant. As long as it complied when installed, and isn't unsafe; it can remain in service [ESR 13] .So as long as the new work complies with current rules should be OK.
Except that ESR 13 requires that work not make any part of the installation not worked on less safe than it was.
So you need to consider whether the in-fill structure being supplied PEN would have any adverse effect on the safety of the existing outbuildings.
One safety issue is touch voltage; especially the risk of simultaneously-accessible items, that are earthed via different earth fault paths being at significantly different potential. The longer the earth paths, the greater the differences in potential are likely to be, especially under earth fault conditions. That's why the PEN submain option is only available for outbuildings.
Any interconnections between the different parts of a combined outbuilding will effectively result in the multiple MENs being in parallel. Which in turn mains all the submain neutrals are now in parallel with each other. It's important to avoid any such parallel connections, even accidental ones.
That's why the definition of "combined outbuilding" refers to the structures being on common foundation, or sharing conductive components eg roofing or framing.
Having the several MENs in parallel also means that load current can flow in protective earthing conductors - and that violates 8.3.8.1 (a).
Which is why we no longer have N-E connections in DBs; except if the DB is in an outbuilding using PEN supply.
Overall; despite maybe - at a stretch - being technically compliant with the letter of 5.5.3.1(b) as per 2007 edition; I don't believe it's OK to call this multiple structure 'three outbuildings'. It's really turning what was 2 outbuildings into a single outbuilding with 3 supplies, and that means the existing parts of the installation no longer comply with the original rule about only one MEN link in any outbuilding
---------------
In the other hand; there are plenty of cases where a common structure includes several separate installations, each with own PoS, mains, and MSB.
Often the several PoSs are in a common location, that may also include metering etc. Eg blocks of shops or flats. The common conductors upstream of the PoSs are not "mains' but private works (installations are not allowed to share conductors).
This shows why it's important to be certain of location of PoS -
Go to full postThe key issue is where is the point of supply (or points of supply).
Remember that metering, occupancies, and similar are not relevant to definitions of installation.
the meter enclosure, c/w electrode, presumably also has an MEN link.
Assuming all one installation with a single PoS; then this will be the MSB.
Therefore must also include the main switch(es).
The 2 x existing structures will be outbuildings, each fed by PEN submain as per 5.5.3.1(b).
Which is acceptable provided they are separate structures; both WRT the structure containing the MSB and WRT each other.
For purposes of Wiring Rules, these are regarded as "separate MEN installations"; and this affects not only the earthing but also main switch requirements.
However for purposes of ESRs they are all part of one large electrical installation (as defined in Electricity Act); which starts at the point of supply (point of supply is also defined in the Act). So as far as ESRs are concerned,
The proposed in-fill structure will change the circumstances, effectively there will be no separation between the 3 'outbuilding" structures, in fact there will be only one structure containing several separately-supplied parts of the installation - in this case,three .
This meets the definition of 'combined outbuilding" (new in 2018 edition); any number of structures , containing more than one supply, and on same foundation or sharing conductive roofing / framing. Under 2018 edition, PEN supply is not permitted for "combined outbuildings".
Currently 2018 edition has not yet been cited, and MBIE has declared intent to have dual-citation with 2007 (though this may change).
So unless / until that citation occurs (and perhaps even afterwards), these "new" rules around supply to "combined outbuildings" are not mandatory.
So it might seem compliant (with 5.5.3.1(b)) to treat the 3 parts as each being a different "outbuilding" . Each of the three "outbuildings" has separation from the structure that contains the MSB; so meets the definition. Each will have only one MEN within it, so 'complies' with item (i).
NOT good practice, because this is exactly what the 2018 edition is trying to prevent; but technically compliant (with 5.5.3.1 (b)).
However this interpretation only works if you can, hand-on-heart, say there are 3 structures rather than one.
5.5.3.1(b) is not the only consideration, and there are other rules that also apply.
Under both ESRs and Wiring rules, what happened earlier isn't directly relevant. As long as it complied when installed, and isn't unsafe; it can remain in service [ESR 13] .So as long as the new work complies with current rules should be OK.
Except that ESR 13 requires that work not make any part of the installation not worked on less safe than it was.
So you need to consider whether the in-fill structure being supplied PEN would have any adverse effect on the safety of the existing outbuildings.
One safety issue is touch voltage; especially the risk of simultaneously-accessible items, that are earthed via different earth fault paths being at significantly different potential. The longer the earth paths, the greater the differences in potential are likely to be, especially under earth fault conditions. That's why the PEN submain option is only available for outbuildings.
Any interconnections between the different parts of a combined outbuilding will effectively result in the multiple MENs being in parallel. Which in turn mains all the submain neutrals are now in parallel with each other. It's important to avoid any such parallel connections, even accidental ones.
That's why the definition of "combined outbuilding" refers to the structures being on common foundation, or sharing conductive components eg roofing or framing.
Having the several MENs in parallel also means that load current can flow in protective earthing conductors - and that violates 8.3.8.1 (a).
Which is why we no longer have N-E connections in DBs; except if the DB is in an outbuilding using PEN supply.
Overall; despite maybe - at a stretch - being technically compliant with the letter of 5.5.3.1(b) as per 2007 edition; I don't believe it's OK to call this multiple structure 'three outbuildings'. It's really turning what was 2 outbuildings into a single outbuilding with 3 supplies, and that means the existing parts of the installation no longer comply with the original rule about only one MEN link in any outbuilding
---------------
In the other hand; there are plenty of cases where a common structure includes several separate installations, each with own PoS, mains, and MSB.
Often the several PoSs are in a common location, that may also include metering etc. Eg blocks of shops or flats. The common conductors upstream of the PoSs are not "mains' but private works (installations are not allowed to share conductors).
This shows why it's important to be certain of location of PoS -
Re: Multiple Electrical Installation
You have called this a multiple installation, and it may be that. Equally it could be a collection of separate installations.
The key issue is where is the point of supply (or points of supply).
Remember that metering, occupancies, and similar are not relevant to definitions of installation.
the meter enclosure, c/w electrode, presumably also has an MEN link.
Assuming all one installation with a single PoS; then this will be the MSB.
Therefore must also include the main switch(es).
The 2 x existing structures will be outbuildings, each fed by PEN submain as per 5.5.3.1(b).
Which is acceptable provided they are separate structures; both WRT the structure containing the MSB and WRT each other.
For purposes of Wiring Rules, these are regarded as "separate MEN installations"; and this affects not only the earthing but also main switch requirements.
However for purposes of ESRs they are all part of one large electrical installation (as defined in Electricity Act); which starts at the point of supply (point of supply is also defined in the Act). So as far as ESRs are concerned,
The proposed in-fill structure will change the circumstances, effectively there will be no separation between the 3 'outbuilding" structures, in fact there will be only one structure containing several separately-supplied parts of the installation - in this case,three .
This meets the definition of 'combined outbuilding" (new in 2018 edition); any number of structures , containing more than one supply, and on same foundation or sharing conductive roofing / framing. Under 2018 edition, PEN supply is not permitted for "combined outbuildings".
Currently 2018 edition has not yet been cited, and MBIE has declared intent to have dual-citation with 2007 (though this may change).
So unless / until that citation occurs (and perhaps even afterwards), these "new" rules around supply to "combined outbuildings" are not mandatory.
So it might seem compliant (with 5.5.3.1(b)) to treat the 3 parts as each being a different "outbuilding" . Each of the three "outbuildings" has separation from the structure that contains the MSB; so meets the definition. Each will have only one MEN within it, so 'complies' with item (i).
NOT good practice, because this is exactly what the 2018 edition is trying to prevent; but technically compliant (with 5.5.3.1 (b)).
However this interpretation only works if you can, hand-on-heart, say there are 3 structures rather than one.
5.5.3.1(b) is not the only consideration, and there are other rules that also apply.
Under both ESRs and Wiring rules, what happened earlier isn't directly relevant. As long as it complied when installed, and isn't unsafe; it can remain in service [ESR 13] .So as long as the new work complies with current rules should be OK.
Except that ESR 13 requires that work not make any part of the installation not worked on less safe than it was.
So you need to consider whether the in-fill structure being supplied PEN would have any adverse effect on the safety of the existing outbuildings.
One safety issue is touch voltage; especially the risk of simultaneously-accessible items, that are earthed via different earth fault paths being at significantly different potential. The longer the earth paths, the greater the differences in potential are likely to be, especially under earth fault conditions. That's why the PEN submain option is only available for outbuildings.
Any interconnections between the different parts of a combined outbuilding will effectively result in the multiple MENs being in parallel. Which in turn mains all the submain neutrals are now in parallel with each other. It's important to avoid any such parallel connections, even accidental ones.
That's why the definition of "combined outbuilding" refers to the structures being on common foundation, or sharing conductive components eg roofing or framing.
Having the several MENs in parallel also means that load current can flow in protective earthing conductors - and that violates 8.3.8.1 (a).
Which is why we no longer have N-E connections in DBs; except if the DB is in an outbuilding using PEN supply.
Overall; despite maybe - at a stretch - being technically compliant with the letter of 5.5.3.1(b) as per 2007 edition; I don't believe it's OK to call this multiple structure 'three outbuildings'. It's really turning what was 2 outbuildings into a single outbuilding with 3 supplies, and that means the existing parts of the installation no longer comply with the original rule about only one MEN link in any outbuilding
---------------
In the other hand; there are plenty of cases where a common structure includes several separate installations, each with own PoS, mains, and MSB.
Often the several PoSs are in a common location, that may also include metering etc. Eg blocks of shops or flats. The common conductors upstream of the PoSs are not "mains' but private works (installations are not allowed to share conductors).
This shows why it's important to be certain of location of PoS -
The key issue is where is the point of supply (or points of supply).
Remember that metering, occupancies, and similar are not relevant to definitions of installation.
the meter enclosure, c/w electrode, presumably also has an MEN link.
Assuming all one installation with a single PoS; then this will be the MSB.
Therefore must also include the main switch(es).
The 2 x existing structures will be outbuildings, each fed by PEN submain as per 5.5.3.1(b).
Which is acceptable provided they are separate structures; both WRT the structure containing the MSB and WRT each other.
For purposes of Wiring Rules, these are regarded as "separate MEN installations"; and this affects not only the earthing but also main switch requirements.
However for purposes of ESRs they are all part of one large electrical installation (as defined in Electricity Act); which starts at the point of supply (point of supply is also defined in the Act). So as far as ESRs are concerned,
The proposed in-fill structure will change the circumstances, effectively there will be no separation between the 3 'outbuilding" structures, in fact there will be only one structure containing several separately-supplied parts of the installation - in this case,three .
This meets the definition of 'combined outbuilding" (new in 2018 edition); any number of structures , containing more than one supply, and on same foundation or sharing conductive roofing / framing. Under 2018 edition, PEN supply is not permitted for "combined outbuildings".
Currently 2018 edition has not yet been cited, and MBIE has declared intent to have dual-citation with 2007 (though this may change).
So unless / until that citation occurs (and perhaps even afterwards), these "new" rules around supply to "combined outbuildings" are not mandatory.
So it might seem compliant (with 5.5.3.1(b)) to treat the 3 parts as each being a different "outbuilding" . Each of the three "outbuildings" has separation from the structure that contains the MSB; so meets the definition. Each will have only one MEN within it, so 'complies' with item (i).
NOT good practice, because this is exactly what the 2018 edition is trying to prevent; but technically compliant (with 5.5.3.1 (b)).
However this interpretation only works if you can, hand-on-heart, say there are 3 structures rather than one.
5.5.3.1(b) is not the only consideration, and there are other rules that also apply.
Under both ESRs and Wiring rules, what happened earlier isn't directly relevant. As long as it complied when installed, and isn't unsafe; it can remain in service [ESR 13] .So as long as the new work complies with current rules should be OK.
Except that ESR 13 requires that work not make any part of the installation not worked on less safe than it was.
So you need to consider whether the in-fill structure being supplied PEN would have any adverse effect on the safety of the existing outbuildings.
One safety issue is touch voltage; especially the risk of simultaneously-accessible items, that are earthed via different earth fault paths being at significantly different potential. The longer the earth paths, the greater the differences in potential are likely to be, especially under earth fault conditions. That's why the PEN submain option is only available for outbuildings.
Any interconnections between the different parts of a combined outbuilding will effectively result in the multiple MENs being in parallel. Which in turn mains all the submain neutrals are now in parallel with each other. It's important to avoid any such parallel connections, even accidental ones.
That's why the definition of "combined outbuilding" refers to the structures being on common foundation, or sharing conductive components eg roofing or framing.
Having the several MENs in parallel also means that load current can flow in protective earthing conductors - and that violates 8.3.8.1 (a).
Which is why we no longer have N-E connections in DBs; except if the DB is in an outbuilding using PEN supply.
Overall; despite maybe - at a stretch - being technically compliant with the letter of 5.5.3.1(b) as per 2007 edition; I don't believe it's OK to call this multiple structure 'three outbuildings'. It's really turning what was 2 outbuildings into a single outbuilding with 3 supplies, and that means the existing parts of the installation no longer comply with the original rule about only one MEN link in any outbuilding
---------------
In the other hand; there are plenty of cases where a common structure includes several separate installations, each with own PoS, mains, and MSB.
Often the several PoSs are in a common location, that may also include metering etc. Eg blocks of shops or flats. The common conductors upstream of the PoSs are not "mains' but private works (installations are not allowed to share conductors).
This shows why it's important to be certain of location of PoS -
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