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Over Half Single Zone Induction Cookers Failed to Pass All Safety Test Be Wary of 1 Model Exceeded Upper Temperature Limit

  • 2019.12.16

Winter is the peak season for the Chinese hotpot – with many a household rolling out their induction cookers, enjoying the hotpot at home. Out of 12 models of single zone induction cookers recently put to a test by the Consumer Council, more than half of them were found unable to fully pass all of the safety test items. In particular, 1 model exceeded the standard upper limit in the heating test. In the performance test, the standby power consumption of the models varied by over 4 times and the variations in heating speed were equally significant, the time taken to heat up 1 litre of water (from 15℃ to 90℃) among the 2,000 watt models differed from 3.5 to 4.5 minutes, and in the case of a claimed 1,000 watt model up to 13 minutes. Consumers should pay heed to the safety and performance of the cookers and exercise caution in their use in strict accordance with the instructions of the operation manuals.

In collaboration with the Electrical and Mechanical Services Department, the test covered 12 models of tabletop single zone induction cookers comprising 9 models of 24mm wide ordinary induction cookers and 3 models of under 24mm mini induction cookers. In the former category the input electrical energy was generally higher, ranging from 2,000W in 6 models to 2,100W in 3 models while in the latter mini models from 1,000W to 1,300W. Retail price ranged from $279 to $699, with 8 models offering a pot with lid or a small teapot as free gift. The test focused mainly on safety, performance and convenience of use. 

The test was conducted in reference to the latest version of the International Standard IEC60335-2-9, IEC60350-2 and GB21456. Safety test items included the construction, heating test and marking instructions. A total of 7 models were found failed to fully comply some of the safety test items.

In the heating test, the magnetic coils of 1 mini model whilst in normal operation were measured to exceed the standard upper limit of 75K with a temperature rise to 108K. If these coils were to operate over a prolonged period of time, it may accelerate the aging of the insulation system and, in a serious case, set off a short circuit.

The test found also when a proper cookware was placed on the cooktop, the on/off switch of 2 induction cooker models could easily be turned on, with the slightest touch on the panel, to start heating instantly in non-compliance of the standard which requires that heating could only be activated by pressing 2 buttons on different locations. When using these products, consumer should be aware of not to switch on the appliance accidentally and causing burns.

In the performance test, 12 models varied widely in terms of their average standby power consumption, from 0.35W to 1.81W. Effective this month, induction cookers are included in the Mandatory Energy Efficiency Labelling Scheme (MEELS); which 6 models were issued with or under the application of Energy Labels ranging from Grade 2 to Grade 5. Some of the models received lower efficiency grades due to their high standby power consumption in spite of their satisfactory operation efficiency performance. For instance, 1 model with wireless function scored the best in operation efficiency of 83%, despite its standby power consumption was the highest. Based on an electricity unit cost of $1.2, the model with the highest standby power consumption would cost $19 a year just for standing by. Consumers are urged to disconnect the cooker from the electrical supply after use so as to support sustainable consumption by avoiding energy wastage.

On their heating per litre of water with the highest power from 15℃ to 90℃, wide variations were recorded from 3 min 41 sec to 13 min 53 sec. Even among the ordinary cooker models with similar input electrical energy of 2,000W, the time varied from 3 min 41 sec to 4 min 38 sec, a difference of nearly 1 minute. As the input electrical energy of mini induction cooker models was lower and their operation efficiency and heating speed were clearly inferior to the ordinary cookers, the heating time for the worst performing model took 13 min 53 sec.

In general induction cookers are featured with a range of different cooking programs or different power levels. In assessment of their low power control, the test found half (6 models) of them were relatively weak, with rating of only 3.5 points or lower. The temperature overshoot of the cooktop after cooking was assessed, the ordinary cooker models were found to store up more heat to as much as 70℃ temperature rise that could cause burn injury when touched or contacted accidentally.  

In the test, 80% (10 models) were measured to have an actual average input electrical energy lower than 95% of their claims, the discrepancies being 6.1% to 37.7%; the shortfalls among 6 of the models were all higher than 10%, manufacturers are urged to make immediate improvement.

Furthermore, the size of the high temperature warning markings on 2 models fell below the standard requirement, with 1 model without any explanation of the significance of such warning in the instructions manual. Moreover, 1 model was not labelled with the double insulation marking while 6 models provided no specific warning statements in the instructions manuals, for instance, stop the use of the cooker immediately when crack is detected, never place metallic objects on the hotplate, and operate the device with an external timer.

In the scrutiny of the instruction manuals, 4 models were found without an English version, and 2 models with unreasonable claims – 1 model claimed suitable for use of cookware 2.5cm wider in diameter than the induction cooker width while another model with a heating efficiency of 99%. Manufacturers are urged to improve their product labelling and quality of content disclosure to ensure accuracy of information.

Consumers using induction cookers should pay heed to the following:

- Always keep the cooker surface clean, never place such objects as cans or knives or forks on its top;

- Read carefully the instructions manual, choose cookware of suitable size, and do not plug in or turn on the electrical supply before placing the cookware on the cooker;

- When cracks are found on the cooktop, stop using it immediately and contact the agent for maintenance or replacement;

- Avoid touching the cooker right away after cooking to minimize the risk of burn injury;

- Disconnect the plug from the electrical supply after use to save energy.

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