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Aircon Power Trip!

There are generally 3 types of power tripping:

1) It trips the ELCB (Earth Leak Circuit Breaker) or the RCCB (Residual Current Circuit Breaker).

That's the big circuit breaker with the blue lever. It is often installed on the left, the first one. It will be written ELCB or
RCCB. If you are interested in what's the difference between this two, there's this answered question in Yahoo Answers!

elcb rccb

ELCB & RCCB respectively.

If it trips the ELCB or RCCB, it's really no good news. It means that there is a short circuit. If it is caused by turning on
the air conditioner, usually, it is a burnt out compressor.

You tried lifting up the blue level but every time you do so, it comes down again. Don't worry, all you need to do is to
bring down all of the MCBs. In case you don't know what they are, they are those "other" circuit breakers, yes, that
whole stretch of circuit breakers on the right (hope I'm not confusing you further).


On the MCB, there will be a number. The number represents the current rating. Most HDB approved air conditioner for
use in Singapore hardly exceed 12 amperes (running amperes). But MCBs are usually fitted larger to accommodate for
surges during start-up. Usually, a 16A - 20A MCB is installed for air conditioner use.

If it trips the MCB, your air conditioner is drawing very high current, either during start up (thus, check the starting
capacitor) or gradually increases after some time. Need to check the gas pressure, are you over charging it? A dirty
condenser can draw high current too. It can also be a result of the condenser fan. If it spins too slowly, it cannot
effectively cool down the condenser and that will cause pressure build up, thus high ampere.

3) It trips the MAIN circuit breaker (outside of the apartment)

This kind of tripping is usually associated with a loud bang and that will probably worry many people. It must be
something serious and yes indeed, it is very serious. The LIVE wire had short circuited with the NEUTRAL cable.

Fortunately, this problem may turn out to be a small problem. How does live wire short circuit with the neutral cable?

twisted cable joint

This problem is often caused by poor workmanship. When electrical cable is not long enough, they could have been
joint together by twisting the cables together and insulating those using tape as seen on picture above. This is a
common practice for "electricians".

Nevertheless, one must understand that such joints must be water proof when used in an air conditioning system. This is
because these cables are often placed inside the PVC casing together with the copper pipes and condensate water

When the system is new, things works pretty fine. But as the system becomes old, the inside of the PVC casing may
become wet as the copper pipe insulation degrades. The electrical tape that were used to insulate the electrical cable
may become lose too. Once water creeps between the cables, it will cause the power to trip, often with a loud bang.

Follow the "bang" and open up the casing, repair the damaged cable and insulate the cables properly.