Just been looking at definitions in ESRs and although a lot of people talk about main switches as they are part of mains work it's actually just the connection of mains to them that is mains work? Correct?
Just curious in regards to inspection of mains work if things such as main switch height or location actually fall under the inspectors jurisdiction for pass or fail
Or as per usual with other aspects like switchboard location, RCD arrangements etcetc that they can simply advise and/or make a complaint to EWRB but can't actually fail an installation based on clauses to do with main switches
Just been looking at the definition of mains and mains work in ESRs for reference
Is a main switch actually part of mains work?
Re: Is a main switch actually part of mains work?
Along the same lines for inspection of mains work - if an installation is using a strip-type earth electrode which in NZ is required to be 7.5m long an buried at 0.5m or more.
Is this something that inspectors should be inspecting? With a driven electrode, you can reasonably assume that it is the correct length.
But there's many ways that a strip electrode could be installed wrong, such as doubling it back on itself, or just coiling it up and throwing it in the trench..
Is this something that inspectors should be inspecting? With a driven electrode, you can reasonably assume that it is the correct length.
But there's many ways that a strip electrode could be installed wrong, such as doubling it back on itself, or just coiling it up and throwing it in the trench..
Re: Is a main switch actually part of mains work?
WRT main switches:
The definition of "mains work" includes work on "mains"; and that definition is
"fittings forming part of an installation that are used for the supply of electricity to the MEN switchboard that is closest to the point of supply.
"fittings" includes conductors but is not limited to conductors.
At the network / supply end, the same conductors may continue beyond the point of supply (typically at the boundary);
but upstream of the POS is not part of the installation, and therefore those parts of the conductors are not "mains".
So work on that part can't be "mains work".
in the middle, non-conductor fittings, such as mains entry boxes, are used for supply to the first MEN switchboard; and are therefore "mains' just as much as the conductors that connect to them.
Revenue metering and load control fittings installed upstream of the 1st MEN swbd are also "mains"; which is why definition of "mains work" has a special exclusion relating to installation of meters.
At the other end, once you've reached the specified switchboard the fittings are no longer supplying electricity to the switchboard.
So technically "mains" only extends as far as the switchboard enclosure; and within the switchboard is no longer "mains".
However most would accept "mains" as extending to the first terminals; which for smaller installations is generally the line terminals of the "main switch(es)."
Other than those controlling alternative / supplementary supplies, a "main switch" is part of the "main switchboard",
and therefore can't be fittings supplying that switchboard, and therefore not "mains".
It follows that installing a main switch for a normal LV supply is not "mains work"; and therefore not subject to inspection.
At fullest extent; "mains"' & "mains work" can only extend to the line terminals of a main switch.
Under earlier Regs, the work that required inspection was defined differently; and unfortunately many practitioners haven't fully adjusted their thinking.
The definition of "mains work" includes work on "mains"; and that definition is
"fittings forming part of an installation that are used for the supply of electricity to the MEN switchboard that is closest to the point of supply.
"fittings" includes conductors but is not limited to conductors.
At the network / supply end, the same conductors may continue beyond the point of supply (typically at the boundary);
but upstream of the POS is not part of the installation, and therefore those parts of the conductors are not "mains".
So work on that part can't be "mains work".
in the middle, non-conductor fittings, such as mains entry boxes, are used for supply to the first MEN switchboard; and are therefore "mains' just as much as the conductors that connect to them.
Revenue metering and load control fittings installed upstream of the 1st MEN swbd are also "mains"; which is why definition of "mains work" has a special exclusion relating to installation of meters.
At the other end, once you've reached the specified switchboard the fittings are no longer supplying electricity to the switchboard.
So technically "mains" only extends as far as the switchboard enclosure; and within the switchboard is no longer "mains".
However most would accept "mains" as extending to the first terminals; which for smaller installations is generally the line terminals of the "main switch(es)."
Other than those controlling alternative / supplementary supplies, a "main switch" is part of the "main switchboard",
and therefore can't be fittings supplying that switchboard, and therefore not "mains".
It follows that installing a main switch for a normal LV supply is not "mains work"; and therefore not subject to inspection.
At fullest extent; "mains"' & "mains work" can only extend to the line terminals of a main switch.
Under earlier Regs, the work that required inspection was defined differently; and unfortunately many practitioners haven't fully adjusted their thinking.
- Rating: 16.67%
Re: Is a main switch actually part of mains work?
WRT inspection of earth electrodes:
"mains work" includes work on the "main earthing system"; which includes the earth electrode.
Therefore ESR 70 (3)(a) requires the inspector to be "satisfied" that the work of installing the electrode has been done in accordance with ESRs.
So the compliance of the electrode with the requirements set for type, location, installation, etc are all matters that are within the scope of high risk PEW that is required to be inspected.
It's up to the individual inspector to decide what it takes to "satisfy" them, case by case.
Any part of the high risk PEW that is hidden, eg by being buried, is difficult to check.
The inspector may choose to take some matters on trust; but in doing so they are accepting additional risk / liability.
Some may be happy with photographic evidence.
Assuming that a driven electrode has reached the required depth is just as likely to be wrong as assuming that a horizontal one has been laid at acceptable depth, or long enough. Some driven electrodes available on the market, intended for other purposes, simply don't have sufficient length for the minimum depth plus a bit for above-ground connection / testing point.
On the other hand, horizontal electrodes are generally laid in same trench as mains, so non-compliant depth will affect both; but will matter far more for the mains than the electrode, being a safety issue as well as a technical compliance issue.
Not fully meeting specification isn't going to have much adverse effect on effectiveness of an electrode; especially given there is no required level of effectiveness. Effectiveness of individual electrodes isn't the point; what matters is the overall effect of multiple electrodes in parallel WRT keeping the distribution N at close to same potential as mass of earth. Ohms law for resistances in parallel applies.
"mains work" includes work on the "main earthing system"; which includes the earth electrode.
Therefore ESR 70 (3)(a) requires the inspector to be "satisfied" that the work of installing the electrode has been done in accordance with ESRs.
So the compliance of the electrode with the requirements set for type, location, installation, etc are all matters that are within the scope of high risk PEW that is required to be inspected.
It's up to the individual inspector to decide what it takes to "satisfy" them, case by case.
Any part of the high risk PEW that is hidden, eg by being buried, is difficult to check.
The inspector may choose to take some matters on trust; but in doing so they are accepting additional risk / liability.
Some may be happy with photographic evidence.
Assuming that a driven electrode has reached the required depth is just as likely to be wrong as assuming that a horizontal one has been laid at acceptable depth, or long enough. Some driven electrodes available on the market, intended for other purposes, simply don't have sufficient length for the minimum depth plus a bit for above-ground connection / testing point.
On the other hand, horizontal electrodes are generally laid in same trench as mains, so non-compliant depth will affect both; but will matter far more for the mains than the electrode, being a safety issue as well as a technical compliance issue.
Not fully meeting specification isn't going to have much adverse effect on effectiveness of an electrode; especially given there is no required level of effectiveness. Effectiveness of individual electrodes isn't the point; what matters is the overall effect of multiple electrodes in parallel WRT keeping the distribution N at close to same potential as mass of earth. Ohms law for resistances in parallel applies.
- Rating: 50%