Why does my power supply trip when I turn on my aircond?

You come home after a long, hot day. You settle into your comfy seat, and turn on the aircon. 

But when you do that, the aircond turns itself off. Or worse, the power in your entire room goes out. And this happens every time you do it.

Before you call an electrician or an aircon technician to check the problem, it’s worth understanding the potential causes. Sometimes, it could be an easy fix, such as cleaning your aircon filters.

What is a power trip, anyway?

A power trip is when the circuit breakers in your house turn off by itself, cutting off power supply in one area of your house, or cutting off power in the entire house.

Every house has a service panel (also called a distribution box, or DB) where all the electricity flows through. Inside this panel, there are circuit breakers that detect changes in electrical current. When set up properly, these circuit breakers are designed to trip if it detects an overload, short circuit, sudden surge, or electrocution. 

This helps protect wiring from getting overheated (and causing a fire); surges from damaging other areas of the house; and also protects lives.

Reasons why your aircon is causing a power trip

According to Glenn from Up Your Home Services (a Recommend.my vendor), there are three common reasons the aircon is causing a power trip:

Compressor damage

The outdoor unit contains a component called a compressor. Its basic purpose is to compress the refrigerant to “release” the heat that it absorbed from your room, and send it out into the open air. The refrigerant is then piped back into your room to absorb more heat and cool your room air, and the cycle continues.

Compressor component in aircon unit
Above: Compressor component in aircon unit

As it is located in the outdoor unit, it can experience wear and tear due to exposure to sun and rain.If the compressor unit is damaged, it may draw too much amperage, or create a short circuit, causing your house circuit breaker to trip.

In this case, it will need to be replaced. Unfortunately, compared to other spare parts, this vital component is one of the most expensive components to replace. Prices of spare parts could start from RM500 for a traditional 1-to-1 aircon split unit, excluding labour.

In condominiums, the repair cost could be even higher. Many condos use one outdoor condenser unit to power multiple indoor units. This is known as a multi-split unit, or VRV/VRF system (variable refrigerant volume / variable refrigerant flow). This is commonly found in condominiums because there is not enough balcony space to fit many outdoor condenser units.

“In multi-split units, the cost to replace a damaged compressor could go into the thousands of Ringgit. That’s because after a compressor like this is replaced, we also need to do nitrogen flushing to blow out contaminants in the entire refrigeration system. That in turn means that we may need to cut open plaster ceilings to get access. It’s almost like a complete overhaul.”

Glenn from Up Your Home Services

Bad aircon wiring

An aircond’s internal system is made up of a complex network of components and wires that keep the system running smoothly. However, over many years of service, the aircond wires could become loose, or the insulation could get worn out. This can cause a short circuit and trip your circuit breaker.

Frayed or loose wiring can also become an electrocution hazard. If the aircon keeps tripping, call an aircon technician or qualified electrician to check the issue as soon as possible.

Too many appliances overloading the circuit

You probably know that you should not plug in too many appliances into one extension plug.

Similarly, you should not install too many aircon units into the same power supply.

In electrical wiring terms, every house is divided into zones. And each zone is connected to a single circuit breaker, which allows a maximum amount of power. For example, the kitchen may be rated for 5000W, and the bedrooms may get 4000W.

So, if you plug a 1000W aircon, a 1500W kettle and a 1500W iron into a single zone, and switch them all on at once, you are already running dangerously close to the limit. This will almost certainly trip the circuit breakers.

“I have seen homes where the previous aircon installer connected three aircon units into a single circuit breaker that is only rated to handle one unit. Of course, the breakers immediately tripped when they tried to switch them all on at once. What they should have done is to add another circuit breaker to spread the load.”

Glenn from Up Your Home Services

The lesson is: when hiring an aircon installation service, make sure they are verified and qualified to do the job.

Other reasons your aircon is cutting off

When you turn your aircon on, it may simply cut off by itself, without tripping the circuit breakers of your house.

This can indicate a problem with the aircon unit itself, such as:

Clogged air filter causing overheating

A clogged air filter is common when maintenance of the aircond is neglected. The build-up, which is made up of dust, dirt and other airborne particles that are trapped by moisture, will cause the aircond motor fan to work extra hard to get to the desired temperature. The clogged filters may create a build-up of trapped heat, or overheat the motor, causing the unit to cut off on its own.

By keeping to a regular cleaning schedule you will be able to keep the air filter from clogging up and the motor fan from overworking.

Dirty condenser or evaporator coils

The indoor fan unit and outdoor unit contain metal coils that absorb heat from the inside of the room and transfer it to the outside. But dirty coils can prevent this heat exchange from happening properly.

Again, this can cause the motor to overheat or break down, causing the unit to turn off by itself. Arrange for an aircon servicing to diagnose these issues.

Refrigerant issues

If your aircon gas or refrigerant has leaked out over time, it will take a longer time for the unit to cool the air. This causes the aircon to work at maximum power for long periods of time, which could cause overheating and a power cut off. An aircond technician can check the refrigerant pressure and bring it back to proper levels. 

Aircon Chemical Cleaning

What should I do If my aircon keeps tripping the circuit breaker?

If your circuit breakers trip the moment you turn on your aircon, you can take a look at your electrical service panel (also known as a distribution box, or DB). This is usually behind your front door, or in a wiring closet near your entrance.

Your DB consists of two types of circuit breakers. The MCB (miniature circuit breaker) trips in case of overloaded wiring in a given zone in your house. While the RCCB (residual current circuit breaker) trips in case of electrocution, or current being grounded unexpectedly.

Above: Electrical service panel in a residential house, showing the miniature circuit breaker (MCB) and earth leakage circuit breaker (ELCB). Each MCB supplies power to a specific area in the house, such as the kitchen or living or master bedroom.
Above: Electrical service panel in a residential house, showing the miniature circuit breaker (MCB) and earth leakage circuit breaker (ELCB). Modern homes now use a residual current circuit breaker (RCCB) to replace the ELCB. Each MCB controls the power to a specific area in the house, such as the kitchen or living or master bedroom.

If only one of the MCBs has tripped, this helps you narrow down the problem to one area of your house. You may have too many appliances in that area. 

If the RCCB has tripped instead, it could be a sign of damaged wiring or damaged electrical components. Learn more from TNB website

If you can’t figure out what’s causing the power trip, don’t ignore this problem and hope it will go away on its own. Power trips could be a sign of larger electrical issues that could result in damage, burns, fires, or electrocution. It’s best to call a professional aircond technician or electrician to check.

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