i opened up the switch socket done by developer and aircond contractor for additional aircond point

developer , got 2 yellow, 2 black and 2 green, total 6 wires.

aircond contractor , got 2 red and 2 black.

anyone know is it still fine ? what are the differences ?


Update:
contractor say earth direct DB, now all people install like this. is that fine for the switch safety ? anyone can illustrate the wiring diagram ?

Indoor 3 wires


Outdoor 3 wires


Switch , 2 live , 2 neutral


This post has been edited by Pain4UrsinZ: May 29 2021, 07:55 PM

no earthing, it is for safety purpose.
but with black and red only the AC will work fine.

i would like to make sure it is safe even though people think it is unnecessary .
if want to add now the earth wires will need to connect all the way to the DB ? any other alternate way ? because now the DB patched it back already and plaster ceiling is up.

This post has been edited by Pain4UrsinZ: May 29 2021, 05:09 PM

You are correct. Safety is up most important.

U can check if ur AC does provide the earth or not (i believe all big brand will have, and is a requierment). If yes, u will need to redo the whole cabling.
Yes earthing normally runs together with the black and red lines. form DB to the AC unit. best to have 1 breaker for 1 AC.

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"
-------------------------------------------------------------------------------


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

open indoor unit ignore L, N tap E see trip or not if you know what you doing

This post has been edited by zuozi: May 30 2021, 03:11 AM

it's fine. the switch does not require earth.

i'll use a multimeter to check earth to live and live to neutral potential first before installing aircond. (dont diy if you dont know what you are doing)

if potential difference is the same between the 2 or more or less the same, it is good to go.

This post has been edited by slimey: May 30 2021, 09:21 AM

the switch & powerpoint provided by contractor itself has 6 wires (2 earth wires included) however when the contractor pull the cooper piping and wiring to the ODU, i only see 3 wires and the same for IDU.

as per the picture is the extra air cond point and switch by the contractor.

This post has been edited by Pain4UrsinZ: May 30 2021, 11:51 AM

i think it is something like this, the difference is my aircond No control line and using power as signal. i checked my aircond compressor it has L1,L2,L3 and Earth, but the cable has only 3 wires, how are they connecting it ? isolator and double pole switch is different ?


This post has been edited by Pain4UrsinZ: May 30 2021, 11:53 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


Attached thumbnail(s)

damn ,need to hack plaster ceiling to check earthing and replace the cable.

any recommendation for contractor who wiling to help me to clean up the mess ? hope no need to pay additional cost for copper piping and superlon.

will need to do again after MCO.

even with earth wire use as signal at outdoor unit.......

technically the outdoor unit is earthed as it is connected with indoor unit via copper piping. and indoor unit is earthed.

but a direct earthed outdoor unit is of course better and safer.

how about the signal from ODU to IDU ? aircond still work properly without signal wire ?

if they use earth wire as signal wire........it will work

in that case i still have my earth ? what is the purpose of the signal wire ?

hiaz..............

at indoor unit has 3 wire : live, neutral, earth

outdoor unit connected through the gray flexible cable which have 3 wire core : live, neutral, earth.

for normal non-inverter aircon..........no issue. no signal wire needed to communicate between indoor unit and outdoor unit.

for inverter aircon, need signal wire.

if you install inverter aircon, likely installer will just use the earth wire of the flexible cable as signal wire to connect between the indoor unit and outdoor unit.

difficult to understand?

is signal wire & earth still work properly if it is connecting ODU & IDU at the same time also connecting to Earth from DB ?

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

no idea what your sentence mean..........

you want to use the earth wire from the 3 core flexible cable ( the gray one) to have both function as earth and signal?

it will not work.

1. it may trip the rcd
2. even if it work, any fault condition will send huge ac current to the pcb on the inverter module at the outdoor and fry the unit. it is suicidal.

so the solution option is use non inverter air cond or add another wire as signal wire for each of the aircond ?

This post has been edited by Pain4UrsinZ: May 30 2021, 09:38 PM