088 Imam bonjol Street
Central Jakarta
DKI Jakarta 10110

Your water pump just hums and doesn’t spin? This is the cause!

Your water pump just hums and doesn't spin? This is the cause!

Are you experiencing a problem like the title of this article? Is your water pump just hums and not turning even though it has a power supply? Hmm, it looks like you are on the right page to find out what the cause is!

Your water pump just hums and doesn't spin? This is the cause!
Single-phase water pump

Based on my experience, the most common causes of water pumps humming and not turning are as follows.

The water pump just hums because of the Voltage drop

The first reason the water pump just hums and won’t turn is because the electricity in your house has dropped.

Basically, there are several types of water pumps currently on the market, and each water pump has a different power supply from the others. But generally, they are only grouped into 2, namely, water pumps with a 3-phase power supply (380 VAC power supply) and 1-phase (220 VAC).

The water pumps we use on a household scale generally have a small 1-phase power supply (220 VAC).

When you experience that the electrical voltage in your house is far below 220 VAC, that is what is called a voltage drop.

Several well-known water pump brands currently on the market require the supply voltage for the pumps they make to be within a specific tolerance range.

As an example. The well-known water pump brand, Shimizu, provides a voltage tolerance of +- 10% of the nominal voltage. This means that if the water pump works at a voltage of 220 volts, then the maximum and minimum voltage is 220 x 10% = 22 volts.
Minimum: 220-22 = 198 volts
Maximum: 220+22 = 242 Volts

The question now is, why does a voltage drop cause the water pump not to rotate and just hum?

Very good and critical question. In electrical science, we know several terms that are related to each other. For example voltage, current and power.

The formula for calculating electrical power in single-phase equipment is:

P = V x I

P = Power (watts)
V = Voltage (Volts)
I = Electric load (Ampere)

In this case, we take this water pump as an example. On the water pump nameplate, the manufacturer tells us about the electrical power required by the water pump to operate. Suppose the power is 300 watts.

With the voltage that we already know, namely 220 VAC, we can find out how much electricity load we use to operate the water pump, namely:

P = V x I
300 = 220 x I
I = 300/220
I = 1.36 A

So, under normal voltage conditions, the electrical load we use is 1.36 Amperes.

Now what if the mains voltage drops to a nominal 200 VAC?


I = 300/200
I = 1.5 Amperes

It can be seen that if the electric voltage drops, the electric current (Ampere) will be greater.

Do you know? If the electric current flowing through the pump gets bigger, the pump will get hotter and make it stop and not be able to rotate!

That is the answer to why a voltage drop will result in the water pump just buzzing and not rotating or even turning off completely.

So how to solve this voltage drop problem?

To be able to overcome this voltage drop problem, of course, you have to know the source of the problem.

Usually, the voltage drop is caused by your house being too far from the central power plant, or the distribution transformer connecting your electricity source being overloaded.

If this is your problem, then you need to contact your electrical service provider and ask them to move the power source to your house via a normal voltage line.

The final solution that you can use is to use a voltage stabilizer. This tool will help increase the electrical voltage at home to normal voltage, namely 220 VAC.

Voltage stabilizer

The water pump just hums because The capacitor is damaged!

The second cause the water pump just hums is that the capacitor is damaged.

Burned Capacitor

As we know, the function of the capacitor in a single-phase electric motor is to assist the water pump during initial starting. If the single-phase water pump capacitor is damaged, the water pump will not be able to start when given a power supply.

In the photo above, you can see a capacitor that has been burned and damaged. Capacitors in this condition must be replaced with new ones. This is How to check the water pump motor capacitor Is it still good or not?

The solution to this problem is to replace the capacitor.

The water pump just hums because The motor coil is burned out

Burned motor pump coil

One of the fatal consequences of the voltage drop in the case above is the coil burning. If the water pump is forced to run in a voltage drop condition, the electric current flowing to start the water pump will be greater. This will make the motor coil on the water pump easily hot and catch fire. When the motor coil burns out, we have no other option but to replace the pump or rewind the pump which is not cheap.

There is a charred part on the pump motor coil above. Usually called the stator coil. Stator coil damage is the worst damage to a water pump.

OK, those are some of the reasons why the single-phase water pump in our house won’t spin, it just buzzes and feels very hot when you hold the body. If you experience the same problem and need my help, don’t hesitate to leave a comment in the column below!

Share if this is useful....

I am a dedicated and results-oriented Electrical, Instrumentation and Automation Engineer with a strong educational background and experience working in the Sugar and oil and chemical industry. My academic foundation from Unram University has provided me with a solid understanding of electrical engineering principles, and my professional experience has allowed me to apply this knowledge in a practical setting.

Articles: 11

Leave a Reply

Your email address will not be published. Required fields are marked *