Figure 6.7 doesn't match fig 6.8, fig 6.9, or the wording of 220.127.116.11
I know AlecK has explained the string method of determining the zones, but that doesn't prevent zone2 still existing on the other side of a 1.8m screen/barrier because zone 2 is 2.25m high.
This doesn't seem to have changed in 3000:2018 either.
Have I got it wrong?
Especially the words that point to the Fig.
Some Figs do introduce requirements that aren't in a clause, but this is regarded as poor practice when writing a Standard.
The default position is that Figs illustrate the requirements.
WRT this clause, the words at the end of 18.104.22.168 are: "Examples of these zones are shown in Figures 6.1 to 6.9".
The key word being "examples"; meaning that while we can expect that they accurately illustrate the requirements, they don't necessarily cover all cases.
Another signal of this is the word 'typical"; either in the clause 'pointer' to the Fig, or in the title of the Fig itself.
I believe all such Figs should include reference(s) back to relevant clause(s).
On the other hand, a Fig that is designed to illustrate a particular aspect may not show unrelated requirements; An example of this is the figs in "3010: 2005" that illustrate rules for changeover devices - but don't necessarily show overcurrent protection or isolation requirements.
Which makes following a Fig, without bothering to read all the clauses, dangerous
That said, I believe that several of the current Figs do not accurately illustrate how 'string measurement' works.
Some errors are minor; but some are more serious.
Next revision is supposed to include a full review of these; and should also include a description of how to apply the string method (which comes from IEC).
Bottom line: zone dimensions can always be worked out from the words in relevant clause.
For shower alone, 22.214.171.124:
(a) Z0 = interior of tray. The bit that, if the drain were plugged, would hold water.
(b) Z1 = above Z0, up to higher of (v) 2.25 above floor or (vi) height of fixed water connection ; and extending to a (cylinder shaped) vertical plane radius 1.2 m from fixed water connection.
(d) Z2 = outside Z1 for another 0.6m, and from floor to 2.25 m above.
BUT - as per para 5 of 6.2.1 - zone dimensions are limited wherever there's a wall, floor, ceiling or door that limits the extent of the room.
And, as per para 4, zone dimensions can also be limited by barriers. General requirement is they have to provide 'effective" protection against water spray; and in some cases a minimum height of barriers is specified in a Note to the clause (should really be Exceptions, but let's not quibble here).
now looking at Fig 6.7:
Z0 shown correctly as interior of tray.
Z1 shown correctly as limited in all direction to < 1.2 m; extending to walls (tip & left) & barriers (bottom & right).
- have to assume the height of these barriers is compliant).
Z2 shown as extending beyond Z1 in direction through shower door; and wrapping around the fixed barrier (r=0.6 )to corner, and further, at reduced radius, until meets bottom fixed barrier.
OK so the room's walls provide a limit to all Zones.
The fixed barrier (heavy black line bottom & part right side) limits Z1; so we must assume it's high enough.
Same for the "door" barrier.
But the Figs show Z 2 extending from the "door" barrier for 600 mm; yet not similarly beyond the fixed barrier.
The clause words do not cover whether a barrier ends all zones (like a wall); or whether barriers just mean one zone stops and next starts.
But if we compare all figs; we can conclude that a barrier means "all Zones stop; apart from any wrap-around effects.
It certainly can't be right to have a "dollar each way".
Both barriers have to have same effect.
My conclusion is that the error is simply showing a door; and that the fig is correct for a shower with no door / curtain.
Either that, or there should be a door but no Z2 at all.
Fig 6.8 has "without barrier" in the title
But then includes a barrier with Z2 beyond it.
Whether this elevation is a section at shower "door" opening, or a cross-section; isn't stated.
My conclusion is that the Z2 shown must be simply the 'wrap-around" from the open side we're looking at / through
Fig 6.9 has a full Z 1 through the open non-barrier side, but not fully wrapped around the end of the barrier - so not correct.
Z2 does fully wrap around, but because Z1 is wrong the error follows through. There certainly should NOT be a "step" in the outer limit of Z2.only wrap-around on the barrier side
well done for spotting the inconsistencies; though in some ways i wish you hadn't.
My way of thinking is that Figure 6.8 is the only one that shows the height of the barrier, which is shown at 1.8 with zone 2 beyond it.
The other figures just show a barrier, they dont show what height it is, some people assume its a 1.8mtr barrier but I prefer to assume that it is a 2.25mtr or higher barrier.
The wording of 126.96.36.199 appears to follow with the above:
188.8.131.52 (c) the note stops Zone 1 at a barrier that is 1.8mtrs or higher.
184.108.40.206 (d) (ii) has Zone 2 going up to 2.25mtrs high, I cant see anything in there that prevents there being a zone 2 unless the barrier is high enough to block out the entire zone eg 2.25mtrs high.
I could be wrong but thats the way that I read it.
For barrier height, it's clear that a (qualifying) barrier limits Z1 even above the top of the barrier.
Which is logical because shower water generally sprays down rather than up
And I believe that, since the Figs are intended to illustrate the rules of the clause, wherever they mention a barrier we are entitled to assume it's of adequate height.
So the question remains, is there a "bext zone" on the other side of a barrier?
or does the barrier effectively end all Zones, other than wrap-around?
The clauses don't clarify this point; and we have to rely on the Figs in order to infer the answer.
Unfortunately there is inconsistency; as some Figs that show barriers indicate next-zone-beyond, and others indicate only wrap-around beyond.
Looking at Fig 6.8 in particular, the Z2 shown below the top of barrier could indicate either next-zone-beyond or wrap-around;
and while the part of Z2 above barrier looks like a case of next-zone-beyond it could also be a misrepresentation of wrap-around
Review of 2018 edition, where we have a couple more Figs that may help.
6.7 (plan, current 6.5) - only wrap-around shown - but "string measurement" not correctly shown
6.8 (plan) - only wrap-around shown
6.10 (plan, current 6.7) - wrap-around for fixed barrier, but zone-beyond for door
6.11 (elevation, current 6.8) - unclear
6.12 (plan, current 6.9) - only wrap-around shown - but "string measurement" not correctly shown
6.17 (plan, current 6.14)- only wrap-around shown
Overall; strong indication that all Zones stop at a barrier, apart from wrap-around effect.
Only one fig clearly suggests "zone-beyond"; and in that case maybe the door shown isn't a qualifying barrier.
The other, being the only "barrier" elevation, could be showing a cross-section through a wrap-around.
These requirements are based on IEC 60364-7-701; which only ever shows wrap-around and never shows zone-beyond.
And, incidentally, shows Z1 wrap-around at the top of a barrier where the barrier is not as high as the zone limit
(with words to match).
To me, if the barrier is deemed adequate to control spraying water, then it's entirely logical to treat it the same as a wall / floor / ceiling: no zones beyond the barrier other than wrap-around.
On the other hand, if you do apply next-Zone rules beyond barriers you can't be "wrong";
I think you can say that the barrier for fig 6.7 is most likely a shower screen even though you are not given that information. The figure shows the barrier stopping all zones except for wrap around indicating that any sufficient barrier stops all zones not just a full height wall.
Figure 6.8 always was the one that gave me trouble as I thought it didn’t match with the wrap around shown in the other figures. I had always looked at it as though it was a cross section through the barrier though instead of looking at the end of the barrier from an opening. If viewing it this way it does seem to fit in with the information from the other figures.
The diagrams in AS/NZS 3000 show the door hinged along the edge, but they rarely are hinged this way.
The hinge point is always 150mm in from the edge allowing a hand to slip out side the shower.
I didn't install this switch plate.
It's assumed that any door / curtain provided is is shut/ closed when the shower is turned on.
Taking an extreme case, the door curtain could be left open, and the user could stand in the shower holding the handpiece and squirting it at electrical fittings across the room.
But we're not trying to overcome user stupidity.
In this case there's a door, which - as per 6.2.1 para 4 - limits Z1 to interior instead of default 1.2 m from fixed water connection specified in 220.127.116.11(c)II).
so IF there's a "zone beyond"; then the switch is in Z2 as per 18.104.22.168(d)(i).
Therefore 22.214.171.124 (b) requires degree of protection as per 126.96.36.199(b); ie IP X4 minimum.
On the other hand, if there's no "zone beyond"; then no rules apply (WRT the shower - can't see what other Zones may apply for eg bath or basin).
Note that there's no difference in effect between a "barrier" (screen / door / curtain / fixed partition) in para 4
and a wall / ceiling / floor of the room in para 5.
Both limit the relevant zone in exactly the same way.
And nobody? argues that there would be a zone-beyond" on the other side of the wall / floor / ceiling.
So my personal opinion is that Fig 6.8, which shows a "zone beyond" a barrier, is incorrect; because inconsistent with all the other Figs as well as the IEC Standard in which our Zones are based.
I believe Fig 6.7 is also wrong, because it states that the shower is 'enclosed"; and shows a (sliding) door.
That door limits Z1 as per 6.2.1; so it can't be as shown.
However if a complaint came before the EWRB; they may well adopt a different view.
It lets condensation on the tile run down behind the switch and there was next to no room behind the switch because of the framing.
Damp wood touching the backs of switches is a recipe for nuisance RCD tripping, but then the electrician didn't wire back to the board that was literally 3 feet away, he wired his 2C+E to the 2C permanent live at the ceiling rose. So nothing in the bathroom was earthed at all.
Not even the class 1 towel rail next to the bath.
No excuses, both the bathroom and hallway had dropped ceilings so wiring back to the board would have been easy even in this 2 story building.
The switch ended up there because he didn't allow for the standard sized shower. He should have put the plate on the other side of the wall.
But then this guy replaced the switchboard and never put an earth electrode in, neither did he bother to check if there even was one.
Just wrote on his COC and SWB label, "main earth under house below switchboard"