Can a blown thermal fuse be bypassed by directly connecting the wires? A 10-year veteran repair technician warns: absolutely not! Includes emergency troubleshooting methods and proper repair procedures.

[Key Conclusion] In household settings, if a thermal fuse (also known as a temperature fuse—a critical overheat protection safety component for home appliances) is damaged, it is strictly prohibited to bypass the component by directly connecting the wires and using the appliance permanently. Any fire caused by such unauthorized short-circuiting will not only result in you being fully liable for all property losses and having your insurance claim outright denied, but, in cases of serious consequences, you may also face criminal liability for arson—with no room for negotiation whatsoever.

I am a seasoned veteran with 10 years of experience in home-appliance repair, and I have witnessed over a hundred incidents of fires and equipment damage caused by short-circuiting thermal fuses. Coupled with the national standard GB 9816.1-2019 and the original design specifications of appliance manufacturers, I can provide you with this unequivocal, non-negotiable answer.

Can the thermal fuse be removed and the wires connected directly if it’s broken? Straightforward conclusion:

 

There is only one extreme scenario in which temporary short-circuiting for fault diagnosis is permissible: when components are unavailable in remote areas, a short-term emergency fault investigation is required, and all stringent conditions are simultaneously met—namely, low power, no heating, no enclosure, and continuous on-site supervision. Beyond this specific situation, any instance of short-circuiting, regardless of the context or duration, amounts to gambling with one’s life.

I. Can the thermal fuse be removed and the wires connected directly if it’s broken? Straightforward conclusion:

1.1 Permanent short-circuiting is strictly prohibited! This is a non-negotiable requirement stipulated by national standards and design specifications.

A thermal fuse is the “ultimate safety switch” for household appliances and is a one-time, non-recoverable overheat protection device.

Its mission is to completely disconnect the power supply by melting itself when all protective devices, including thermostats and conventional fuses, fail, thereby preventing uncontrolled temperature rise that could lead to fire.

Its design and manufacturing strictly comply with the national standard GB 9816.1-2019, “Electrical Automatic Controllers for Household and Similar Applications—Thermal Fuses,” making it a safety component required by law.

Removing it and connecting the wires directly = dismantling the last safety safeguard for the appliance.

I have handled far too many real-world cases:

After the user short-circuited the appliance and used it for six months without incident, the temperature controller eventually stuck, causing the rice cooker to burn through the inner pot, ignite the kitchen cabinets, and set the entire kitchen ablaze. Not only did the homeowner suffer losses amounting to several hundred thousand yuan, but the fire also spread to neighboring units, requiring full compensation for damages—and ultimately resulting in legal liability as well.

This item is designed to protect against the one-in-a-million fatal accident; normally, you hardly even notice it’s there. But when disaster strikes, having it makes all the difference between spending five yuan and losing an entire house.

Therefore, permanent shorting must never be allowed—no exceptions.

1.2 Only one extreme scenario allows for temporary short-circuiting; failing to meet even a single requirement is absolutely unacceptable.

First, draw a clear red line: only one scenario across all use cases permits temporary short-circuiting; all other scenarios strictly prohibit such operations.

If you’re in a rural or remote area, it may be impossible to procure parts of the exact specifications or find a certified technician—and yet you have an urgent, mission-critical need to quickly diagnose and resolve equipment malfunctions.

Moreover, short-circuiting should only be used for temporary troubleshooting to identify the root cause of a fault; it must never be employed under normal loaded conditions, nor should one assume that as long as the system is monitored continuously, everything will be fine and continue operating normally.

This emergency scenario must simultaneously meet all four of the following conditions; failure to meet even one is strictly prohibited:

Conditions	Specific rigid requirements
① Equipment limitations	Only low-power, non-heating, non-enclosed household appliances with a power rating of no more than 50 W are permitted (such as desk lamps and USB mini fans). Any appliance that features heating, has a sealed chamber, or exceeds 50 W in power—such as rice cookers, water heaters, air conditioners, electric pressure cookers, and induction cookers—must be strictly prohibited, even if used for only a minute.
② Full-time on-duty	Power must be turned off when no one is present; even a brief absence of 30 seconds requires unplugging the device. Operating equipment unattended with power on is strictly prohibited.
③ Strict duration control	Operation must be strictly limited to no more than 2 hours and is intended solely for fault diagnosis and verification of the condition of other components; it shall not substitute for routine maintenance and is strictly prohibited from being used during normal equipment operation.
④ Eliminate obvious faults	Prior to energization, verify that the equipment is free of obvious faults such as short circuits, severe overloads, and motor stalling; otherwise, an accident will occur as soon as power is applied.

Any deviation from even a single rule constitutes a high-risk violation.

I’ve seen users bypass the safety mechanisms of a rice cooker to cook noodles in an emergency—while they were just gone to fetch some water, the pot overheated and started smoking. There’s also been a case where someone bypassed the safety circuit of an electric water heater and took a 10-minute shower, only to have the temperature control fail, the inner tank overpressurize and leak, nearly causing burns, and the wiring completely charred. Let me emphasize this again: when it comes to heating appliances and pressure-rated appliances, there is absolutely no room for “just using them temporarily as a quick fix.”

1.3 The Four Non-Negotiable Red Lines for Temporary Short-Circuiting

Red Line One: It is strictly forbidden to bypass the circuit with the intent of “long-term use.” The sole purpose of a temporary bypass is to buy you time to purchase replacement parts and arrange for professional repair—it is by no means intended to allow you to operate the equipment normally. Many users, after making a temporary bypass and finding that everything seems to work fine, simply forget about it, only to later suffer catastrophic consequences.

Red Line No. 2: Any form of direct wiring is strictly prohibited for high-risk appliances, including so-called “temporary emergency” connections. This includes, but is not limited to: electric water heaters, gas water heaters, air conditioners, heat pumps, rice cookers, pressure cookers, induction cookers, microwave ovens, electric heaters, and similar devices. These appliances are inherently prone to overheating and fire hazards; removing the thermal fuse effectively creates an immediate fire risk, leaving no room for the notion of “safely using it temporarily.”

Red Line 3: Under no circumstances should you blindly bypass the fault by short-circuiting before identifying and eliminating the root cause. Remember: when a thermal fuse blows, in 99% of cases it’s not due to a defect in the fuse itself—rather, it’s because another part of the equipment has malfunctioned, causing overheating. The fuse is simply alerting you to the problem! If you remove the warning device while the underlying issue remains, the fault will persist; upon power-up, it’s highly likely that even more expensive core components will burn out, or worse, a fire could break out.

Red Line 4: Users without an electrical background are prohibited from performing any operations on their own. Even for temporary emergency measures that meet all requirements, basic skills in power disconnection, voltage verification, and insulation treatment are essential; otherwise, electric shock and short-circuit accidents can easily occur.

II. The Core Function of Household Thermal Fuses: Understanding Why They Should Not Be Removed Arbitrarily

2.1 Operating Principle: Temperature-Triggered, Single-Use Fuse

Household thermal fuses (temperature fuses) are manufactured in strict accordance with national standards and consist of three core components: a temperature-sensitive element, a fusing mechanism, and electrode leads.

Normal state: The temperature-sensitive granules are in a solid state, pressing against the fuse mechanism, keeping the circuit closed and the device operating normally—with no perceptible presence at all.

Overheat Protection: When the internal temperature of the device reaches the calibrated trip temperature (Tf), the temperature-sensitive element melts instantaneously, causing the spring mechanism to release and permanently disconnect the circuit in an irreversible manner.

Operating temperature: For household appliances, it typically ranges from 100°C to 240°C, with precise matching based on the specific characteristics of each device. For example, rice cookers usually operate at 130°C to 185°C, air-conditioner compressors at 120°C to 150°C, and water heaters at 150°C to 220°C.

This threshold is precisely set between the component’s maximum safe operating temperature and the flash point of flammable materials, serving as a finely engineered safety safeguard.

2.2 Its “Ultimate Safety Net” Role in Home Appliance Safety Protection

The vast majority of home appliances employ a three-level protection architecture:

Level	Component	Core Features
Level 1	Functional temperature control (rice-cooking temperature control, temperature sensor)	Daily temperature adjustment to ensure equipment operates within its normal temperature range.
Level 2	Resettable Thermostat (Bimetallic Strip)	Disconnects under mild overheating and automatically recovers upon cooling, effectively handling sporadic abnormalities.
Level 3	Thermal Fuse (Ultimate Protection)	When the first two levels of protection fail, a one-time circuit breaker trips to immediately cut off power, completely eliminating the risk of fire.

Removing the thermal fuse is tantamount to dismantling this final safety safeguard.

I once repaired an air conditioner that had been short-circuited. In summer, the compressor’s temperature control failed, causing the temperature to soar above 200°C, which immediately locked the compressor and burned out the main control board. Originally, a mere 5-yuan thermal fuse would have fixed the problem, but in the end I ended up spending over 2,000 yuan to replace the entire compressor.

2.3 Thermal fuses are not the same as fuses or temperature controllers; their functions are entirely non-substitutable.

Many people mistakenly believe that “it’s all the same—removing it won’t matter,” but this is the most dangerous misconception.

Thermal fuse vs. conventional fuse: A fuse responds to overcurrent—it only blows when the current exceeds the rated limit. A thermal fuse, on the other hand, responds to temperature; even if the current is within normal limits, it will blow as soon as the temperature reaches a preset threshold.

For example, if the thermostat in a rice cooker sticks together and continues to heat, the current will remain perfectly normal and the fuse will not trip; however, the temperature of the inner pot will keep rising. Only the thermal fuse can detect this temperature anomaly and cut off the power supply.

Thermal Fuse vs. Resettable Thermostat: Resettable Thermostats are reusable, but they may experience issues such as sticking, jamming, or failure to trip. Thermal fuses, on the other hand, are single-use devices; once they have operated, they permanently open the circuit and will never “fail to trip.”

In reality, the vast majority of overheating incidents are caused by the sticking of resettable thermal protectors; in such cases, the thermal fuse serves as the ultimate safeguard. The three devices differ entirely in their tripping thresholds, operating characteristics, and protective functions, and none can substitute for the others.

2.4 Removing it is tantamount to removing the “airbag” of home appliances.

To put it in the most straightforward analogy: a thermal fuse for home appliances is like an airbag for cars.

Removing the airbag has absolutely no impact on everyday driving—you won’t even notice the difference. But in the event of a crash, the difference between life and death is stark. The thermal fuse works the same way: under normal conditions, it’s virtually invisible; yet when temperature control fails and temperatures spiral out of control, it becomes the final line of defense that can save your life.

III. [For Extreme Emergency Use Only—Operation Absolutely Prohibited Unless Necessary] Temporary Short-Circuiting Method for Troubleshooting a Thermal Fuse Failure

[Prior Mandatory Warning] The following method is intended solely for the single, extreme emergency scenario specified above and is to be used only for troubleshooting equipment malfunctions. It is absolutely not recommended or encouraged for normal equipment operation, and long-term retention of this method is strictly prohibited.

This method is strictly prohibited for all high-power household appliances with heating elements, pressure-bearing components, and sealed chambers—such as rice cookers, electric water heaters, gas water heaters, air conditioners, and electric pressure cookers—regardless of the application scenario or duration, including so-called “temporary emergency” uses.

Any use beyond the specified scope shall be at the operator’s sole risk, with all associated safety hazards, legal liabilities, and property losses borne by the operator.

3.1 Mandatory Safety Preparations Before Operation (Not a Single Step Can Be Omitted)

All steps in this procedure must be completed in full; failure to complete even one step strictly prohibits any subsequent wiring operations, and users without an electrical background are prohibited from performing these operations independently.

Step 1: Completely disconnect power and verify that the circuit is de-energized. Unplug the appliance from the power outlet; under no circumstances should you perform any work on a live circuit, even for low-voltage small appliances such as 5V devices—always unplug them first. Use a multimeter set to the AC voltage range to measure the voltage across the terminals of the thermal fuse and between the fuse terminals and ground; ensure the reading is zero. For appliances with large capacitors (such as air conditioners and induction cookers), discharge the capacitor first to prevent electric shock from residual stored charge.

Step 2: Identify obvious faults. Inspect the interior of the equipment for signs such as burnt wiring, swollen components, short circuits, or motor stalling. If any of these conditions are present, direct wiring operations are strictly prohibited—applying power will immediately cause a short circuit and result in damage.

Step 3: Prepare the necessary compliance tools and materials. Tools: insulated-handle screwdrivers, wire strippers, multimeters, and other standard electrical tools. Conductors: Only use solid copper-core wires with the same gauge as the original wiring; the use of thin iron wire or aluminum wire is strictly prohibited. Insulation: Flame-retardant heat-shrink tubing combined with high-voltage insulating tape; the use of ordinary adhesive tape is strictly prohibited.

Step 4: On-site safety precautions. Keep away from flammable and explosive materials, and equip with dry powder fire extinguishers. Operating in damp or wet environments is strictly prohibited.

3.2 Step-by-Step Practical Procedure for Direct Wiring

Only those who have completed all safety preparations as specified in Section 3.1 and fully meet the eligibility criteria for emergency scenarios may proceed with the following operations; high-risk household appliances are strictly prohibited from being operated.

Step 1: Locate and remove the damaged thermal fuse. Open the housing, identify the thermal fuse—typically cylindrical or square with two leads—connected in series within the live wire circuit and mounted near the heating element, and verify that it is completely disconnected by measuring across its terminals with a multimeter set to the continuity mode. Use a soldering iron or wire cutters to carefully desolder the faulty component, then clean the terminal connections to remove any solder residue and oxidation, ensuring a clean and reliable electrical connection.

Step 2: Fabricate the adapter connecting lead. Cut a solid copper-core wire to the appropriate length, ensuring its gauge matches that of the original live wire. Strip 3–5 mm of insulation from both ends, then tightly twist the copper cores together into a bundle, making sure there are no loose strands or burrs to prevent short circuits.

Step 3: Wiring and Securing. Firmly connect both ends of the lead wire to the two terminals of the original thermal fuse. For circuit-board soldering: use a soldering iron to make secure, full solder joints, ensuring there are no cold joints or bridging. For terminal crimping: use crimping pliers to firmly crimp the lead wire onto the terminal, ensuring it is securely fastened with no looseness. After wiring is complete, use a multimeter in continuity mode to verify that the circuit is properly connected.

Step 4: Double-layer insulation protection (the most critical step—never skip it!). First, slip flame-retardant heat-shrink tubing over the wiring connections and any exposed conductors, then use a hot-air gun to heat and fully shrink the tubing until it completely encases the wires. Next, wrap 2–3 layers of high-voltage insulating tape over the outside, applying a half-overlap wrapping technique, with the wrapping extending at least 10 mm beyond each end of the heat-shrink tubing. Once the insulation is complete, use a multimeter to measure the insulation resistance between the wiring connections and the metal enclosure or grounding terminal; ensure the reading is greater than 2 MΩ and that there is no leakage current.

Step 5: Route and secure the wiring. Use cable ties to fasten the wires to the original wire clips inside the equipment, keeping them away from heat-generating components, motors, fans, and other moving parts. Ensure that the wires will not be abraded or damaged by heat during operation.

3.3 Temporary Testing After Wiring and Red-Line Full-Process Control

No-load power-on test: Temporarily reset the enclosure, then plug in and apply no-load power for 30 seconds. Observe for any abnormal noises, unusual odors, smoking, or arcing, and use an infrared thermometer to measure the temperature of wiring connections and key components. If any abnormalities are detected, immediately disconnect the power and halt the test.

Short-term fault-diagnosis test: After confirming normal operation under no-load conditions, the equipment may be briefly energized for fault diagnosis, with a dedicated supervisor on continuous watch at all times; leaving the site is strictly prohibited. Temperature must be continuously monitored, and the temperature at wiring connections must not exceed 60°C. If any abnormalities are detected, immediately disconnect power.

Red-line full-process control for emergency use (must be 100% strictly adhered to):

A dedicated operator must be on duty at all times, with constant visual oversight of the equipment. Power must be maintained only while someone is present; if anyone leaves, the power must be immediately disconnected. Even a brief absence of 30 seconds requires unplugging the device. Unattended operation is strictly prohibited.

Within a 1-meter radius of the equipment, it is strictly prohibited to place flammable materials such as paper, cloth, plastic, and oils; ensure adequate ventilation, and provide dry powder fire extinguishers on site.

The cumulative power-on duration must be strictly limited to no more than 2 hours, and the equipment shall be used solely for fault diagnosis and verification of the proper functioning of other components; overnight operation or use for normal equipment operation is strictly prohibited.

Inspect equipment temperature and wiring conditions every 15 minutes; the temperature at wiring connections must not exceed 60°C. In the event of abnormal temperature rise, unusual odors, or abnormal noises, immediately disconnect power.

Upon completion of the inspection, immediately disconnect the power supply and remove all temporary wiring; leaving temporary wiring in place for an extended period is strictly prohibited, and formal repair or replacement must be completed within 72 hours.

3.4 Common Misconceptions and Pitfalls for Beginners

Misconception 1: Performing work on energized equipment. The most common and potentially fatal mistake made by beginners is skipping the safety step of de-energizing the circuit for convenience. Even low-voltage equipment poses an electrocution risk and can even lead to short circuits and arcing. To avoid this pitfall: Strictly adhere to the golden rule: “Unplug first, verify no voltage, then proceed with work.”

Misconception #2: Using substandard materials for wiring. Commonly, people resort to thin iron wire, aluminum wire, or headphone cable—materials with insufficient gauge that overheat and melt, easily causing sparks and fires. To avoid this pitfall: always use pure copper-core wire of the correct gauge, paired with flame-retardant heat-shrink tubing and high-voltage insulating tape.

Misconception #3: Inadequate insulation. Simply wrapping with ordinary electrical tape—or worse, leaving metal exposed—can easily lead to short circuits, leakage current, and electric shock. To avoid this pitfall: always use a double-layer protection system of heat-shrink tubing followed by insulating tape, and verify there is no leakage by measuring the insulation resistance.

Misconception 4: Powering on the equipment blindly without first identifying and addressing the root cause of the fault. Regardless of why the thermal fuse has blown, the power is turned on as soon as the wiring is connected. If the thermostat has become stuck, energizing the circuit will result in dry burning and potentially a fire. To avoid this pitfall: before connecting the wires, thoroughly check for obvious faults such as short circuits, stalled motors, and thermostat malfunctions; and monitor the temperature continuously during operation.

Misconception #5: Treating temporary wiring as permanent use (the most common and highest-risk misconception). Once it’s found to work, people keep using it indefinitely, completely losing sight of its original emergency purpose—and ultimately triggering a serious accident. How to avoid this pitfall: Clearly define the duration of the emergency setup beforehand, dismantle it immediately after the inspection is complete, promptly replace the thermal fuse with one of the same specifications, and carry out proper, formal repairs.

IV. What are the critical safety risks associated with bypassing the thermal fuse and connecting the wiring directly?

4.1 Electrical Fire Risk: From Fault to Ignition in as Little as 3–5 Minutes

According to data from the Fire and Rescue Bureau of the Ministry of Emergency Management, electrical fires have consistently accounted for more than 30% of residential fires, remaining the leading cause. Among these, fires triggered by unauthorized removal or short-circuiting of thermal protection devices make up over 15% of all electrical fires.

Most such fires occur at night when no one is present, and by the time they are discovered, the blaze has already spiraled out of control, posing a severe risk of casualties.

The core logic behind fire outbreaks caused by short-circuiting is that the equipment enters an uncontrolled “runaway heating” state. When the thermostat sticks, continuous heating ensues; once the temperature exceeds 200°C, the plastic housing and insulation begin to melt, releasing flammable gases. At temperatures above 300°C, these materials ignite, setting off nearby combustibles and causing the fire to spread rapidly.

High-power appliances—such as rice cookers, water heaters, and air conditioners—can have heating capacities exceeding 1,000 watts. Once a fault occurs, they can ignite flammable materials in as little as 3 to 5 minutes, leaving virtually no time for emergency response.

Even more dangerous is that many users place short-circuited appliances in enclosed spaces such as kitchens and bedrooms, and some even leave them powered on overnight without supervision—whether for scheduled cooking or all-night warming. If the temperature-control system fails and no one notices, the consequences could be disastrous.

One point many people overlook: if a fire is caused by illegal bypassing/shorting, even if you have homeowner's insurance the insurer will refuse to pay on the grounds of "unauthorized alteration of electrical wiring, unauthorized removal of safety protection components." You not only bear your own losses, but if the fire spreads to neighbors you must pay all compensation; in serious cases you may face criminal charges.

4.2 Electric shock and short-circuit risk: remove the protective cutoff and the entire appliance can become live.

The thermal fuse is connected in series in the live wire circuit. When an overheating fault occurs, it melts and directly cuts off the live wire, leaving the entire appliance de-energized and preventing the appliance body from becoming live and leaking current due to insulation melting.

If it is removed and the wires are directly connected: even during severe overheating, the live wire remains conductive. High temperatures can melt the wire insulation and component encapsulation, causing the live wire to contact the metal casing directly so the whole appliance is energized. If a user touches the casing or a button, they will receive an electric shock. In moist environments (bathroom water heaters, kitchen rice cookers) body resistance drops and 220V is enough to cause ventricular fibrillation and respiratory arrest — immediately fatal.

Short-circuit risk is equally deadly: overheating causes the insulation to melt and carbonize, shorting the live and neutral wires; the short-circuit current can reach tens of times the normal operating current instantly. This produces massive electric arcs with temperatures of thousands of degrees Celsius, instantly igniting all nearby combustible materials. It also trips the distribution box; if the circuit breaker is faulty or improperly rated, this can further cause the incoming wiring to overheat, the electric meter to burn out, or even building-wide power distribution failures.

Many users who bypass the fuse find that "the moment it's powered on the breaker trips"; the core reason is that overheating has already damaged the insulation and caused a short. If someone forcibly resets the breaker or replaces it with a higher-rated one, it will directly cause the wiring to catch fire.

4.3 Accelerated insulation aging risk: a 'slow knife' that plants a long-term hidden danger.

Even without acute failures in daily use, removing the thermal fuse causes the wiring to run at elevated temperatures over the long term, accelerating insulation aging. This hidden danger is very covert and easy to overlook.

There is a well-known "8°C rule" for electrical insulation materials: for every 8°C increase in operating temperature, service life is halved. This isn't theoretical — it's obvious in repairs: wiring exposed to long-term high temperatures can become so brittle within two or three years that it crumbles, whereas under normal conditions it would last for many years.

Normal internal wiring temperatures for household appliances are 40°C–60°C. Without the thermal fuse there is no overheat protection; even slight everyday overloads, poor heat dissipation, or high summer temperatures can cause operating temperatures to climb abnormally. For example, in summer a compressor may be 20–30°C hotter than usual, and the area around a rice cooker's inner pot can be more than 15°C hotter during keep-warm operation.

Prolonged high temperature → accelerated insulation aging, embrittlement, cracking → dramatically reduced insulation performance → leakage, arcing → further temperature rise → vicious cycle, ultimately leading to a sudden short circuit and fire during routine use. Many devices that were bypassed catch fire months or even years later for this reason.

4.4 Legal liability and insurance denial risk: unauthorized wiring modifications, bear the consequences yourself.

Legal responsibility: According to Article 28 of the Fire Protection Law, it is forbidden to remove or disable fire-fighting facilities or equipment without authorization. The thermal fuse in household appliances is a built-in fire-safety protection component; removing or bypassing it constitutes an illegal alteration of electrical wiring. If this causes a fire resulting in casualties or significant property loss, pursuant to Article 115 of the Criminal Law one may be prosecuted for the crime of causing a fire and sentenced to fixed-term imprisonment of three to seven years; if the circumstances are minor, to up to three years' imprisonment or criminal detention.

Insurance claims and warranty: Appliance manufacturers' warranty terms clearly state: "Damage caused by unauthorized disassembly, circuit modification, or replacement with non-original parts is not covered." Once a bypass has been made, the manufacturer has the right to deny warranty service. For household property insurance and fire liability insurance, when a fire is caused by an unauthorized bypass the insurer will issue a denial of claim. You must bear your own losses and your neighbors' losses — a single incident can cost millions, wiping out a family.

5. What irreversible damage can long-term bypassing cause to appliances?

5.1 Irreversible destruction of core components: a 5-yuan issue turned into a 2,000-yuan major repair.

Core appliance components (compressor, heating plate, main control board, motor) account for 60%–80% of the machine's cost, and they all rely heavily on protection from the thermal fuse.

Compressor/motor burnout: windings tolerate up to about 150°C; if this is exceeded the insulating varnish instantly melts and carbonizes, causing inter-turn short circuits and failure — the part must be replaced, costing over 1,000 yuan. Main control board failure: chips and thyristors tolerate up to about 125°C; high temperatures directly destroy them, causing black screens and loss of functionality; full replacement costs 200–500 yuan.

Cascading destruction: once a problem occurs after bypassing, it's a chain reaction. I once repaired an induction cooker where the heating plate melted, and the IGBT, rectifier bridge, and MCU all burned through — everything but the casing was ruined, so it had no repair value and was discarded. All of this happened because someone saved that 3-yuan thermal fuse.

When the cost to replace core components exceeds 70% of the price of a new unit, the device is considered beyond economic repair and should be scrapped.

5.2 Dramatic reduction in overall service life: 8–10 years becomes 3–5 years before scrapping.

Appliance design life is based on a complete protection system and normal operating temperatures. Without the thermal fuse, all components operate at elevated temperatures for long periods and their aging accelerates exponentially.

For example: Refrigerator: normal design life is 10–15 years. After bypassing, the compressor's operating temperature in summer can be more than 30°C higher, causing lubricants to deteriorate faster, increased wear, declining cooling efficiency year by year, and doubled power consumption. Typically within 3–4 years the compressor will seize and stop cooling, reducing the life by over 70%. Washing machine/air conditioner motors: prolonged high temperatures cause bearing grease to dry out and permanent magnets to demagnetize, resulting in noise, vibration, and power loss — a component designed to last 10 years may fail seriously in 3–5 years.

5.3 Chain reaction of failures: a minor fault becomes a major one.

The thermal fuse is not only a protection component but also a fault-warning device. When it melts it is telling you "the device is overheating abnormally — find the root cause!"

Directly bypassing and ignoring this warning lets the device continue to run while 'sick': the root fault keeps worsening, triggering more related failures, with a single fault evolving into a multi-component chain failure.

Typical rice cooker case: thermostat sticking causes the thermal fuse to blow → user shorts it to continue using → thermostat sticking not resolved, inner pot remains overheated → heating plate runs dry, deforms, and its resistance drifts → high temperature accelerates aging and deformation of the sealing gasket, causing leaks and boil-over → rice soup flows into the interior and corrodes the main control board and wiring terminals → ultimately many faults occur: no heating, unresponsive buttons, short-circuit trips, etc. What would have cost tens of yuan to replace the thermostat + thermal fuse ends up requiring replacement of the heating plate, main control board, and gasket, with repair costs increasing more than tenfold.

5.4 Repair costs rise exponentially: from a few yuan to several thousand.

A proper repair replacing a thermal fuse with the same specifications: parts 1–5 yuan, plus labor, total cost not exceeding 50 yuan.

After shorting causes core component damage: Air conditioner compressor replacement: parts 800–1,500 yuan + labor + refrigerant, total cost 1,500–2,500 yuan (a new 1.5‑hp air conditioner unit costs only 2,000–3,000 yuan). Water heater: shorting causes the heating element, main control board, and tank to fail; repair costs 500–800 yuan, while a new 60L unit costs only 800–1,200 yuan — typically scrapped.

Moreover, shorting it yourself voids the warranty; all costs are borne by you. Even if the device has a quality issue, unauthorized modification of the circuit will disqualify free after-sales service.

6. Don't want to replace parts? Safer temporary emergency solutions for thermal fuse failure.

[Core preliminary principle] Any emergency plan must be premised on inspecting and eliminating obvious root causes. Without checking the root cause, even temporary measures are extremely dangerous. All high-risk appliances with heating or pressure-bearing functions strictly prohibit any form of temporary shorting; they must be powered off and wait for proper repair.

6.1 Before emergency measures, first check the root cause (can be done by beginners).

The vast majority of thermal fuse failures are caused by device overheating; without eliminating the root cause, any emergency measure is a gamble.

Step 1: Check for improper human operation. Has the rice cooker or pressure cooker run dry, is the inner pot not seated properly, is the sealing ring deformed causing overflow? Are the air conditioner's or refrigerator's ventilation outlets blocked by debris or poorly ventilated? Is the washing machine overloaded or is the motor stalling? Eliminating these human factors directly removes many overheating risks.

Step 2: Check for a resettable thermostat. Locate the device's bimetal thermostat and check for deformation, sticking, or burning. Manually press the reset button (some models have one), and use a multimeter to measure continuity — at room temperature it should be conductive, showing no sticking or open circuit.

Step 3: Check wiring and core components for obvious faults. Look for burnt wiring, damaged insulation, or loose connections. Check motors, compressors, and heating elements for bulges, burning, abnormal noises, or seizing. If any of these are present, absolutely do not perform any emergency powering.

Step 4: Clean the cooling system. Remove dust and debris, check that cooling fans rotate normally, and ensure ventilation openings are clear. Poor cooling is a frequent cause of thermal fuse blowing; cleaning dust can greatly reduce overheating risk.

6.2 Three temporary alternative protection schemes better than direct shorting.

The following schemes all retain fallback protection, with risks far lower than direct shorting; they are the preferred choices in emergency scenarios.

Scheme 1: Replace with a resettable thermostat of the same specifications (most recommended, safest). Use a resettable bimetal thermostat with the same rated trip temperature as the thermal fuse and a rated current greater than or equal to the device operating current, wired in series in the original thermal fuse circuit and properly insulated and secured. It will automatically open on over-temperature and reset when temperature drops. This achieves overheat protection while allowing temporary use. Risk is only about 5% of direct shorting.

Scheme 2: Replace with a same-spec slow-blow (time-delay) fuse. Use a slow-blow fuse with rated voltage and current matching the original thermal fuse, wired in series in the original circuit. Although it cannot provide precise temperature protection, it offers short-circuit and overload protection and helps prevent catastrophic short-circuit fires. Risk is about 30% of direct shorting. Important: choose a slow-blow type to avoid nuisance blowing from startup inrush; the rated current must match, and it is strictly forbidden for high-power heating appliances.

Scheme 3: Hot-melt glue + micro switch minimal protection (extreme no-parts scenario). Use hot-melt glue with a melting point equal to the rated trip temperature of the thermal fuse to hold down the button of a normally-closed micro switch, keeping the circuit closed. Wire the micro switch in series in the original circuit and install it at the temperature sensing point. When the temperature reaches the glue's melting point, the glue melts, the switch pops, and the circuit is cut. Simple principle; risk about 15% of direct shorting. Note: the micro switch's rated current must exceed the device operating current and secure insulation must be ensured.

6.3 Differentiated emergency handling for different appliance categories.

Risk level.	Appliance category.	Mandatory emergency handling requirements.
Very low risk.	Desk lamps, USB fans, small LED lights (≤50 W, no heating, no sealed cavity).	Only for troubleshooting; may be temporarily shorted, must have double-layer insulation protection, and the same-spec component must be replaced within 24 hours.
Medium risk.	Washing machines, refrigerators, ordinary electric fans (100–500 W, motor-driven, no continuous heating).	Direct shorting is strictly prohibited; must use a same-spec resettable thermostat as replacement, be supervised at all times, cumulative use not to exceed 24 hours, and proper repair completed within 72 hours.
High risk.	Rice cookers, induction cookers, microwaves, electric heaters, etc. (≥1000 W, continuous heating, sealed cavity).	Any form of direct shorting is strictly prohibited! Even so-called temporary emergency measures. Only a same-spec thermal fuse may be temporarily used to trace faults, with dedicated supervision, single power-on not exceeding 10 minutes, and proper repair must be completed within 24 hours.
Very high risk.	Storage-type electric water heaters, gas water heaters, and wall-mounted boilers (high power, pressure-bearing, sealed and water-involved).	Absolutely no emergency power-on under any circumstances! The equipment must be shut down immediately, and a certified professional must be contacted to replace the original factory thermal fuse and to inspect all protective devices. Power-up is strictly prohibited until proper repairs have been completed.

6.4 Duration of Emergency Plan Use and Safety Control Red Lines

Red-line usage durations: Ultra-low-risk small appliances: ≤72 hours; Medium-risk motor-driven appliances: ≤24 hours; High-risk heating appliances: ≤2 hours (with each individual use limited to ≤10 minutes); Extremely high-risk pressure-containing appliances: Any emergency use is strictly prohibited, regardless of duration.

Safety Control Red Lines (all must be observed): 24-hour dedicated on-site supervision: power on only when personnel are present; power off immediately upon departure. Overnight operation is prohibited, and power-on must be scheduled in advance. On-site fire isolation: no flammable materials within a 1-meter radius, and fire extinguishers must be readily available. Continuous temperature monitoring: core components and wiring connections must be checked every 15 minutes; any abnormality requires immediate power shutdown. Overloading is strictly prohibited: equipment may only be operated under no-load conditions for fault diagnosis; full-load or normal-load operation is forbidden.

Emergency Termination Red Line: Within 72 hours after the emergency has been resolved, a genuine, same-specification thermal fuse must be purchased and used to complete formal repairs, thoroughly identifying and eliminating the root cause of the failure. Upon completion of the repair, all temporary measures must be removed, and the original factory wiring configuration must be restored.

VII. Preventing Repeated Burnout: Root Causes of Thermal Fuse Failures and Proper Repair Methods

The key to彻底 resolving the issue is not frequent component replacement, but rather precisely identifying and addressing the root cause of the overheating.

7.1 Investigation of the Four Root Causes of Repeated Blowing of Thermal Fuses

Root Cause 1: Control System Failure (accounting for over 70% of cases): Recoverable issues include burnt or stuck thermostat contacts. Use a multimeter to check continuity—under normal ambient conditions, the circuit should be closed; when heated to the rated temperature, it should open. Temperature sensors (thermistors) may exhibit resistance drift, short circuits, or open circuits; verify against the parameter table. On the main control board, silicon-controlled rectifiers and relays may stick together and fail to disconnect, resulting in continuous heating.

Root Cause No. 2: Cooling System Malfunction—dust accumulation and blockage in the ventilation openings, condenser, and cooling fins. Cleaning the dust can resolve 80% of cooling issues. The cooling fan may be damaged, fail to rotate, or experience reduced rotational speed. Poor installation environment—such as a refrigerator placed directly against a wall or an outdoor air-conditioning unit surrounded by clutter—requires adjusting the clearance to ensure adequate heat dissipation.

Root Cause 3: Overload and failure of core components—motors/compressors: bearing seizure, winding short circuits, and compressor cylinder seizure, leading to locked-rotor overload and overheating. Heating elements/plates: short circuits, leakage currents, and localized overheating due to deformation. Prolonged operation under excessive load: washing machines running continuously at full capacity, or air conditioners operating at full load in extreme high-temperature conditions.

Root Cause 4: Improper component selection and installation—specifically, the replacement thermal fuse has operating temperature and current ratings that differ from the original manufacturer’s specifications. The installation location is offset from the original design point and does not make close contact with the heating element, resulting in inaccurate temperature sensing or premature tripping. Additionally,虚焊 (cold solder joints) on the leads and loose wire connections create high contact resistance, causing the fuse itself to heat up during operation.

7.2 The “Three Core, Two Auxiliary” Golden Rules for Selecting and Replacing Thermal Fuses

The three core parameters must be exactly identical:

Parameters	Rigid requirements
Rated Operating Temperature (Tf)	Consistent with the original manufacturer’s components, with an accuracy of ≤±5°C. Under no circumstances should the temperature be set too high (resulting in loss of protection) or too low (causing frequent false tripping).
Rated Voltage (Un)	For household use, always select AC 250V. Voltages below 220V can cause insulation breakdown and leakage current.
Rated Current (In)	The rating must be equal to or greater than the equipment’s maximum operating current (power ÷ 220 V) and must match the manufacturer’s specifications. A rating that is too low will cause self-heating and false tripping, while a rating that is too high will compromise accuracy.

Two auxiliary parameters must be matched: package type and mounting dimensions—cylindrical, square, or resin-encapsulated—must be identical to the original to ensure tight contact with the heat-generating component. Pin type and length—axial, radial, or leaded—must also be compatible to allow for proper soldering and secure fixation.

Be sure to select genuine, branded components that comply with the national standard GB 9816.1 and bear safety certifications such as UL, VDE, and CQC. It is strictly prohibited to purchase substandard “three-no” products that lack certification and parameter markings.

7.3 Step-by-Step Practical Procedure for Authorized Replacement and Repair

Step 1: Safety Preparations. Unplug the power cord, discharge large-capacitance equipment, and verify that the voltage is zero. Prepare insulated tools, a new thermal fuse of the same rating, solder wire, flame-retardant heat-shrink tubing, and other necessary supplies.

Step 2: Remove the damaged component and document the original factory installation details. Take photographs to record the original mounting location, pin orientation, and cable routing, ensuring that the original factory configuration can be restored.

Step 3: Dismantle and clean. Use a soldering iron to desolder the components; never forcibly pull or yank, as this may damage the pads. Then use a desoldering pump to clean the pads, ensuring they are flat and free of oxidation.

Step 4: Install and solder the new component (the core critical part). Verify the specifications of the new part, then install it in its original position, ensuring tight contact with the heat-generating component. Soldering must be performed quickly, with each solder joint completed in no more than 3 seconds. Prolonged heating can cause the temperature-sensing particles inside the new thermal fuse to melt and fail, rendering the replacement futile. Solder joints should be full, shiny, and free of cold or bridging solder. After soldering, use a multimeter set to continuity mode to verify electrical continuity.

Step 5: Double-layer insulation protection and wiring restoration. Employ flame-retardant heat-shrink tubing combined with high-voltage insulating tape for dual protection. Use a multimeter to verify that the insulation resistance between the wiring terminals and the enclosure is greater than 2 MΩ. Secure the wiring with cable ties, keeping it away from heat-generating and moving components, and restore the original factory wiring layout.

Step 6: Power-on testing and functional verification. Apply power without load for 30 seconds; no abnormalities should be observed. Then operate under load for 5–10 minutes, monitoring temperature with an infrared thermometer to confirm that it remains within normal limits. (This step is optional for qualified personnel.) Use a low-setting hot-air gun to slowly heat the temperature-sensing element and verify that the device trips and cuts off power at the specified set temperature. After testing, the component must be replaced with a new one.

7.4 Daily Maintenance to Prevent Frequent Failure of Thermal Fuses

Adopt proper usage habits: Never operate appliances dry, overload them, or leave them powered on unattended for extended periods (especially heating appliances). If you notice unusual noises, strange odors, or abnormal temperatures, immediately disconnect the power and investigate; do not operate equipment while it is malfunctioning. Place appliances in a dry, well-ventilated, and cool location, ensuring adequate clearance for heat dissipation (at least 10 cm on each side of refrigerators).

Regular Cleaning and Maintenance: Clean dust from the heat dissipation vents, heat sink grilles, and fan every 3 to 6 months. Every 6 to 12 months, inspect the core components—motor, heating element, thermostat, and wiring—for signs of aging, burnout, or jamming. Every 12 months, check the insulation of the wiring and the wiring terminals; tighten any loose connections and replace aged wiring. Additionally, conduct a functional test of safety devices such as the thermostat, sensors, and residual-current devices every 12 months to ensure they are operating properly.

Standardized Repair and Component Replacement: First identify the root cause before replacing the thermal fuse; it is strictly prohibited to replace only the component without addressing the underlying fault. Only certified components of the same specifications must be used, and inferior “three-no” products are strictly forbidden. For high-risk, high-power pressurized household appliances (such as water heaters), it is recommended to contact a licensed professional for repair.

Management of Aging Appliances: According to the “Safety Service Life Standards for Household Appliances,” refrigerators and air conditioners have a safe service life of 10 years, while washing machines, water heaters, rice cookers, and other similar appliances are rated for 8 years. Appliances that have exceeded their recommended service life often suffer from severe internal aging, making thermal fuses prone to failure and significantly increasing the risks of electric leakage and fire. It is therefore advisable to replace such equipment promptly—better to invest in a new unit than to risk costly repairs or accidents down the line.

[Final Safety Reminder] Let me emphasize once again to all our readers: the thermal fuse is the last line of defense for household appliances. Each time it blows, it’s issuing a warning about potential safety hazards in your device. Never, for the sake of saving a few dollars or taking a shortcut, remove this life-saving safeguard. A momentary act of recklessness could lead to irreparable losses.

For any questions regarding the repair, selection, or overheat protection of household appliances that use thermal fuses, feel free to leave a comment in the comments section, and I will answer each one individually.