Risk & Myth of Electrocution of Electric Storage Water Heater in Malaysia
by Mr Choo Wei Seng, ShowerTec Industries Sdn Bhd
Introduction
There are different types and ranges of water heaters in the Malaysian market today, mainly: (1) Electric Instant
Water Heater, (2) Electric Storage Water Heater, (3) Solar Water Heater and (4) Industrial Heat Pump for commercial / hotel applications.
Counting on the number of unit per annum being sold to the market, the Instant Electric Water Heater is always the best seller (500,000 units per year), followed by Electric Storage Heater (80,000 units per year) and Solar Water Heater (20,000 units per year) in Malaysia.
Given the above statistics, Electric Storage Water Heater is another popular method of heating water in Malaysian households, particularly for bathrooms in luxury condominiums, service apartments, SOHO and SOVO, where small-sized storage water heaters (30-50 liters) were installed instead of the Electric Instant Water Heater. Despite the popularity and increasing usage of Electric Storage Water Heater, some aspects of the safety measures are overlooked. They are a handful of fatalities involving water heaters each year.
What actually happened in all cases of Electrocution via Water Heater?
- As per investigation reports, all the fatal cases had failed Residual Current Circuit Breaker (RCCB), which didn’t trip to save lives.
- Most fatal cases had no earth connectivity anymore (due to the building’s unreliable earth wiring), some are due to poor quality of earth rod clamps (rusted & disconnected) and some earth chambers were chopped off during renovations (car porch tiling)
- Non-qualified electricians were engaged to install water heaters where undersized wire was used. After a period of time, the live wire melted and bonded with earth wire, and current then leaked from live to earth.
- External current leakage: when an appliance (such as a kettle, fluorescent lamp) leaks, current combines with failed RCCB and broken mains earthing system, the leak current will be looking for a direct pathway to earth. During this unfortunate incident, if a person is having shower and if the shower system is connected to stainless steel hose and chrome hand shower, he/she will be electrocuted because the current travels through the earth system, through tank’s body, stainless steel hose and then their body to exits through their bare feet to the earth /wet floor.
- As a result of the above, the earth system is electrified and most of the time they are connected by stainless steel hose and conductive chrome hand shower that are exposed to users. If the user touches them, he/she will be electrocuted.
Risk of Electrocution
How much current can kill a person? The chart below explains it:
As shown in the chart, current shock is relatively more severe as the current rises.
For current above 10 milliamps (0.01A), muscular contractions are so strong that the victim cannot let go of the stainless steel hose that is shocking him. At values as low as 20 mA, breathing becomes laboured, finally ceasing completely even at values below 75 milliamps.
Is my house wiring properly wired according to the Electricity Regulation Act?
In Malaysia, the installation of “individual” RCCB with leakage current sensitivity of 10mA in a wet area is a statutory requirement under Electric Regulation Act 1994, however, many houses are only protected by the mains RCCB with the leakage current sensitivity of 100mA.
The wiring regulation assumes that RCCB is always in working condition and also protective earth is reliably connected in all circumstances, and everything is perfect and safe.
However, the ugly truth is that, there are just too many substandard products such as electrical wires that are thinner than the required specifications, varieties of RCCB in different brands that come without SIRIM/ST approval (illegal) flooding the market. Besides that shoddy workmanship conducted by foreign labourers, incompetent and unlicensed electricians who carry out electrical works are worsening the situation.
Now, let us share a few MYTHS in Electrocutions via Water Heater.
MYTH 1
Many think that if the Storage Water Heater is switched off, it will be safe.
FACT 1
Any electrical leakage at home, if earthing and RCCB are not properly functioning, the Earth system in the whole house will be electrified and lead to a high chance of fatality caused by the device, which is the Water Heater, through the Stainless Steel Hose. The reason is simple, because current comes from earth connection at Storage Water Heater tank’s body. As a result, many people perceive that the water heater is causing the electrocution. This perception is wrong, refer to Picture 1.
Picture 1: Showing failed RCCB, and Earth Chamber ground wire disconnected/ broken. Fact: Chances of user touching the Water Heater’s Stainless Steel hose is VERY HIGH.
MYTH 2
Many think that the RCD/ELCB that is built in the Electric Instant Water Heater is the ultimate solution for safety.
FACT 2
Instant Water Heater with built-in RCD/ELCB is only protecting electrical leakage within the water heater itself.
Picture 2: Showing the RCD only protects the circuit after the heater, not before the heater. Fact: Built in RCD in IWH will not trip in the event if current leakage comes from external.
In Malaysia, Electric Storage Water Heaters in the market are without built-in RCD because it is installed above ceiling (hidden from view). Very often a dedicated RCCB with 10mA sensitivity is not installed in conjunction with the Electric Storage Water Heaters. And the only protection comes from 100mA or 300mA rated RCCB in the Distribution Board. The safety solely relies on the working RCCB at the main Distribution Box (DB) and the protective earth connection. Imagine if both of them fail, precious lives will be lost!
Picture 3: Showing Isolation Barrier installed at the inlet and outlet of the Storage Water Heaters, which will
isolate the power connection between tank body to the conductive pipes & stainless steel hose.
Summary
- Water heaters should only be installed by qualified electricians.
- Use only water heaters that are approved by SIRIM and ST (Suruhanja Tenaga). (*you may refer to www.malaysiancertified.com.my for more details)
- Always test the RCCB in your house Distribution Box regularly to ensure its functionality. The requirement says it should be tested 4 times annually.
- House wiring system is recommended to be inspected by qualified electrical contractors every 10 to 15 years for possible deteriorations.
The above are often neglected due to ignorance from users, unscrupulous businesses which sell sub-standard and illegal products in the market, weak enforcement on safety regulations, and many other factors making the installation of water heating systems in a risk-free environment impossible.
In order to adapt to the current situation, Isolation Barrier is a simple and quick solution to prevent electrocution. It has been studied and confirmed that if water is travelling through a 1.0 metre (3.3 feet) long pathway and in a 10 mm inner diameter hose, the electric current will not kill a person even if the person is standing barefoot on a wet floor. Installation Isolation Barrier on water heater is able to mimic the same principles of elongating the water pathway and turn the highly conductive current pathway into a “non-conductive” pathway in the event of electrocution. Refer to Picture 3.
Conclusion
Electric Instant Water Heater users are advised to change to PVC insulated flexible hose and plastic taps at inlet and outlet today. For Electric Storage Water Heater, install the isolation barrier at inlet and outlet of the Storage Water Heater, to avoid failed RCCB and broken mains. It will save lives!
