Storage Water Heater Power Trip: 8 Key Causes and Solutions
Storage Water Heater Power Trip: 8 Key Causes and Solutions
Introduction
Many storage water heater owners have experienced power tripping firsthand. Imagine switching on the heater in the evening, only for the entire house to plunge into darkness. The situation becomes even more frustrating when it happens at night, leaving occupants scrambling for a solution in complete darkness.
A quick Google search for “electrical tripping” often results in a handyman arriving within minutes, seemingly already aware of the issue. After borrowing a ladder, he opens the false ceiling panel, disconnects the wiring from the heater, and then resets the Residual Current Circuit Breaker (RCCB) in the distribution board. The power is restored—except for the now-decommissioned heater.
Strangely, few question whether the handyman is a Licensed Electrical Worker (LEW), possibly due to the urgency of resolving the blackout. He collects between $150 to $250 for identifying the issue and restoring power but offers little to no explanation about the cause.
This article explores the reasons why storage water heaters trip power and how to prevent it.
8 Possible Reasons for Power Tripping
1. Corroded Heating Element Due to Lack of a Sacrificial Anode
Most storage water heaters use a sacrificial anode rod to protect the heating element from corrosion. However, some models, particularly those with stainless steel tanks, do not include a sacrificial anode, making their heating elements more susceptible to corrosion.
Without an anode rod, the heating element deteriorates rapidly when exposed to water, increasing the likelihood of short circuits and power tripping.
Prevention: Regularly inspect and replace the heating element, especially in water heaters that lack a sacrificial anode.
2. Accelerated Corrosion Leading to Small Cracks in the Heating Element
Some heating elements may have design or manufacturing defects that make them more prone to corrosion. The corrosion resistance of heating elements varies by material:
- Titanium (Most Corrosion-Resistant)
- Nickel-Based Alloys (Inconel, Incoloy)
- Stainless Steel
- Copper (Least Corrosion-Resistant)
If your water heater contains a copper heating element, it is more susceptible to corrosion, which can lead to micro-cracks that allow water to seep into electrical components, causing short circuits and tripping.
Prevention: Determine the material of your heating element. If it is copper, schedule routine maintenance and inspections for signs of rust, corrosion, or cracks.
3. Microfractures Due to Repeated Heating and Cooling Cycles
Storage water heaters undergo continuous heating and cooling cycles. Over time, these cycles cause the heating element to expand and contract, leading to microfractures. These fractures increase the risk of water ingress, which can short-circuit the element.
Prevention: Replace the heating element every 3 to 5 years as part of preventive maintenance.
4. Faulty Thermostat Allowing Overheating
A thermostat regulates the water temperature inside a storage heater. If a thermostat is faulty and fails to shut off heating at the set temperature, the element can overheat and burn out, leading to electrical faults and power tripping.
Prevention: Regularly test the thermostat. If the water temperature fluctuates abnormally, replace the thermostat immediately.
5. Melted Cable Due to Undersized Wiring
Using undersized cables (e.g., 3C 70/00076 or 1.5mm² or smaller) can cause overheating, leading to melted insulation and potential short circuits.
A 3000W heating element draws approximately 13A of current, requiring a properly rated cable.
Prevention: Ensure the heater is wired with at least 2.5mm² cables marked BS6004. Avoid outdated cable standards such as 3CX70/0076, which are now illegal for use in water heater installation in Singapore.
6. Improper Cable Connection Without a Junction Box, Connection Unit, or Isolator
Some water heaters are installed without a proper junction box or isolator, leading to loose or unsafe wiring. Poorly connected cables can cause heat buildup, resulting in electrical failures.
This issue is more common when plumbers install the heater without supervision from a Licensed Electrical Worker (LEW).
Prevention: Ensure electrical connections are installed according to SS638 electrical codes under the supervision of an LEW, as required by the Electricity (Electrical Installations) Regulations, Clause 7.
7. Heater Switch Failure
A failing heater switch can cause intermittent power disruptions and tripping. Over time, frequent usage can lead to burnt contacts, resulting in electrical arcing and power failure.
Prevention: Inspect the heater switch yearly and replace it every five years or whenever the heater is replaced.
8. Faulty Residual Current Circuit Breaker (RCCB)
The Residual Current Circuit Breaker (RCCB) is a safety device that trips power when leakage current is detected. If the RCCB itself is faulty, it may trip erratically even when the heater is functioning correctly.
Prevention: Test the RCCB periodically by pressing the test button. For a more accurate test, use specialized devices like the Kyoritsu KEW 6010B to check the heater’s electrical system.
Conclusion
Power tripping in storage water heaters is typically caused by corrosion, faulty components, improper wiring, or electrical overload. The recent increase in failures may be attributed to the use of copper-based heating elements, which are less resistant to corrosion compared to older materials.
Regular maintenance, proper installation, and the use of high-quality components can significantly reduce the risk of power tripping. If your storage water heater repeatedly trips the power, consult a Licensed Electrical Worker (LEW) for diagnosis and repairs to ensure safe operation.
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