Assuming your aircon is Power to IDU / "Power supply: IDU" type
U should run LNE to the IDU; and LNE+Control (4 wire) between IDU-ODU (certain inverter need 4-wire)



Q1
U mentioned developer give 2 earth wires, does this mean both the IDU and ODU points have earthing already?

If I understand correctly:
Earth wire (from IDU back to DB, developer provided
Earth wire (between IDU-ODU is using the 3 core), but here is where A LOT of 4-wire cut corner with a 3-wire (use E as Control)= No effective E at ODU
If the Earth wire (at ODU), dev provided, this also link back to DB, then OK ignore previous point
If NO E at the ODU and your AC is inverter 4-wire IDU-ODU (LNE+Control/Signal), but u only using 3-wire IDU-ODU (as LN+Control) your ODU may NOT have E.

Q2
is that fine for the switch safety ?
Switch point "no need" earth if that's your question.
From IDU point, the Earth bypass switch. Earth is permanently connected. You do not want to switch on/off your "life jacket"
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Loopholes
although you can tap back any earth wire from other circuit but that's technically a code violation (if 2 ppl me and you are stuck on a sinking boat, no-one know how to swim, and I'm having the last life jacket, you're stealing my life jacket if you do it that way); in the case 2 circuit short out to ground at the same time there's only one life jacket.

If there is NO earth at ODU
easiest proper way need to run back one more cable to DB E
or you make a new E path with earth rods etc (complicated); quite a headache as you have to consider bonding back with original earth path

This post has been edited by ceo684: May 30 2021, 03:10 AM

Switch only act upon L+N
DB-IDU point 3-wire is LNE
IDU-ODU point (AC mfg say 4-wire LNE+Signal) but installer panai, smarter than AC mfg engineer, uses 3-wire LN+Signal (using LNE cable), but Signal already hostile takeover E cable, result is there is no E at ODU.

There is no dev-provided E at ODU site (standalone) right? So case #1 does NOT apply.

From your visual inspection at ODU it is definitely 4-wire requirement between IDU and ODU.
Refer to Case #2.
As mentioned, if there is 3-wire cable used for 4-wire IDU-ODU AC installer is cutting corner. Your ODU is not earthed.

Isolator/DP switch is the same functional implied meaning here (acting on both cables L+N).

This post has been edited by ceo684: May 30 2021, 04:09 PM


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1 wire to 1 function.
You cannot share signal function with earth function.



Right now, it works like the titanic, able to move normally, just no lifeboat installed at sea. So it will be fine as long as zero fault occur. It is fine until the iceberg.
Because the lifeboat was used for personal swimming pool back at home on land.

That is what happened to the green wire. Supposed to be used as lifeboat but idiot installer put it at home.

Lifeboat for IDU: OK. earth wire from DB to IDU is already running.
Lifeboat for ODU: 404 not found. It is your IDU to ODU earth wire marked with X that is missing.


IDU have lifeboat.
ODU no lifeboat.

Signal wire purple in my diagram, itu yang CURI your lifeboat green wire.
Signal wire is the telegram machine which operate independently whether or not u got lifeboat.


Ideally..The whole lifeboat story, ie end to end complete earth terminal connection between DB+IDU+ODU as long as two side IDU+ODU have lifeboat, will be enough.

This post has been edited by ceo684: May 30 2021, 09:28 PM

Yes,
NON inverter AC = existing wires are all complete.

If you already bought INV AC = then later on (AFTER MCO) can just add on signal wire, so you can have full safety.

However between NON and INV AC, INV will save on power usage after it has reached target temp (as long as you don't run it crazy cold 16C that cannot be reached)

This post has been edited by ceo684: May 30 2021, 09:48 PM


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yeah.. this is another long term concern also especially concealed wiring all buried inside wall so not easy to fix/access.

This is hard to say because there is some accelerated aging on the insulation. It should still last some time, nevertheless, at least 8 years without problems.
Why 8 years? Extrapolating from car service manual and real life experience with clutch hose condemned, that is about the point where most cars need to really inspect/replace hoses in the engine bay..as they start to age and crack around that lifespan.

No problem (functionally) for the aircon. Some minor efficiency loss because its like putting ice cream in a warm gym room (as the cold pipe and hot pipe are together) but ice cream still edible.

For info.. proper one like Japanese use individually wrapped pipes like Inaba Denko Paircoil. https://www.inaba-denko.com/en/data/series/.../id/E102-00004/

These stuff not cheap in excess of 500+ per 20m roll for up to spec 0.81mm thickness for 6.35/9.52 diameter (1hp typical piping).. piping also got grades one la..just like bread there is a difference between the basic gardenia loaf, gardenia premium and more fancy breads..in piping term got the thin no name china or korean pipe. Then we have acson/daikin pancakes which come on 0.61 and 0.71mm thickness. It is not easy to source 0.8mm locally..that is approaching inaba denko territory.

Consumer already lari when u charge rm10 more than the other guy. How to spec in good stuff leh?