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Budgeting 101: Easy Project – Replacing Dead Air Conditioner Electrical Switch

Electrical Diagram

When there is a fault in the electrical systems in the house, it pays greatly to have some background knowledge on using the right tools and what the different colours of the electrical cables mean. Thankfully the electrical semantics at home is not so completed when it comes to changing the bulb or adding electrical appliances to an existing setup. Image source: Flickr.

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Symptoms Encountered

When we bought the house many moons ago, the bedrooms did not come with any extension for a ceiling fan instead the master bedroom had the usual extension for an air conditioner. So we decided to install an air-conditioner in the master bedroom since the kids usually sleep in the room and get table fans for the rest of the room. To keep the cost down, we maintain one stand fan in the master bedroom so that we can switch that on once the room gets cooler.

We never had any problem with the air conditioner except one time when the air conditioner was working but the air blown in was not cold. When the contractor came to check, he found that the electrical cable from the air conditioner unit to the compressor outside had melted down so the compressor unit was not getting power. Apparently, the guys who installed the air conditioner had used low-quality electrical cables instead of the thicker copper wires. It got fixed immediately and we did not have any electrical issues since then.

Then a few days ago, I noticed the light on the air conditioner switch did not turn on but surprisingly the air conditioner was still working. I thought perhaps the tiny light inside the switch had burned out yes, it was so silly of me! And out of the blue, it just stopped working yesterday evening which means we cannot use the air conditioner at all for the night.

Electrical Switch Old History

Do you still remember the old brown electrical switches made from bakelite and usually lasted a lifetime? The old house had these types of old Bakelite switches and so was most of the switches in school. Image source: PxHere

Faulty Switch Problem

It was nothing much I could do for the night as I need to do some studies first on the possible root causes before deciding on the next move. All the indications show that the key root cause is a faulty switch and the solution is to simply replace the switch.

After buying groceries in the morning, it was time to head to the electrical shop near my house. I showed the photo of the old switch to the guy behind the counter and immediately he said he did not have the same model as it is an old one. The newer model was priced at RM23 and he had two designs which went for the same price. Then I headed back to the house to get the replacement as soon as possible.

Opening the first screw that is holding the switch to the wall was a breeze but the second screw was a tough nut to crack. There seems to be a cover on top of the screw and it seems wedged deeply so trying to pry it open was not successful. Without taking out the cover, there is no way I can get to the actual screw at the back. Obviously, it had to be taken out with brute force since obviously the switch itself is useless and will be replaced.

So I decided to drill the cover so that I can force through a hole in the middle and then pull out. It took some time but I managed to so call tear through the side and the cover came out in pieces. Then it was easy to unscrew the second screw and see what is lying on the back.

YouTube player


The Youtube video that I used to do the replacement as it had the same switch model so it was easy to know which electrical wires went where.

Screwed Wire Colour Codes

I have some experience doing some simple electrical wiring at home so I roughly know the standard colour codes of the wires namely brown or red wire for live, blue or black wire for neutral and green or yellow wire for ground.

The three most commonly used colours are Red, Black and Green. Their uses are:-

Red: The red wire signifies the phase in the circuit and is the live wire and cannot be connected to another red or black wire.

It is often used as a switch leg, in which the wire comes from the bottom terminal of the switch and when the switch is turned on, the wire becomes hot. It is the leg which can be used to turn the load on or off.( need to re-write in simpler form)

Black: Black wires are neutral wires and the wire is connected to a neutral bus bar inside the electrical panel. The bus bar is a conductive piece of metal used for the purpose of distribution.

The black wire can be connected to another black wire, and as it is neutral, it does carry a charge. The charge is the unbalanced load i.e. the return current which flows back into the electrical panel.

Green: The green wires are the grounding/earthing wires in the circuit. The green wire can be connected to another green wire only. The grounding wire is not meant for lights or fans and is used mainly for socket purposes such as in the case of ACs, geysers and other heavy load appliances.

Switches generally have only two wires i.e. neutral and phase. The green wire provides a path to the ground for the circuit’s electric current as it connects to a large copper plate buried in the ground of the society’s meter box.

(Source: RR Kabel)

When I opened the switch, I was in for a surprise – there were only black, blue and green. From what I know black & blue suppose to be neutral so where is the live wire? Worst, the earth wire was not even connected to the switch.

Electrical Wiring House


Electrical Wiring House

The good thing was I had about 3 test pens in my hardware box. The bad news was that none of them was working. So I did not know which wire was live and which breaker to be switched off on the MCB box. Then I managed to “fix” one of the test pens and I managed to identify the live wire – it was a bloody blue one.

Obviously, it is just classic tidak-apa attitude from our local electrical contractors who just want to complete their job but did not step back for a moment to adhere to standards and quality of work.

Final Say

Doing a bit of prep work, the right tools and picking up some basic knowledge helps a lot when it comes to doing minor fix work. One, it saves money by engaging a contractor to do the job and Two, it saves time especially when you need to get it done on the same day and it is the weekend.

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