GB 4706.XX -XXXX  
 
 
ICS 13.120  
K09  
 
 
 
 
National Standard for the People’s Republic of China  
GB 4706.XX -XXXX  
 
 
Safety of Household and Similar Electrical Appliances  
Particular Requirements for Thermal -Storage Hand Warmers  
 
 
 
(Draft for approval)  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Releas ed on ××/××/××××                    Implemented on ×× /××/××××  
Issued by  
 
General Administration of Quality Supervision,  
Inspection and Quarantine of the People’s Republic of China  
Standardization Administration of the People’s Republic of China
GB 4706.XX -XXXX  
Table of Co ntents  
 
Introduction ................................ ................................ ................................ ................................ .......... 3 
1. Scope ................................ ................................ ................................ ................................ .......... 4 
2. Normative reference ................................ ................................ ................................ .................... 4 
3. Terms and definitions ................................ ................................ ................................ .................. 4 
4. General requirements ................................ ................................ ................................ ................. 5 
5. General conditions of tests ................................ ................................ ................................ ......... 5 
6. Classification ................................ ................................ ................................ ............................... 5 
7. Marking and instructions ................................ ................................ ................................ ............. 5 
8. Protection against access to live parts ................................ ................................ ....................... 6 
9. Starting of motor -operated appliances ................................ ................................ ........................ 6 
10. Power input and current ................................ ................................ ................................ .......... 6 
11. Heating ................................ ................................ ................................ ................................ ....6 
Table 101 Max. normal temperature rise ................................ ................................ ............................ 7 
12. Void ................................ ................................ ................................ ................................ ......... 7 
13. Leakage current and electric strength at operating temperature ................................ ........... 7 
14. Transient  overvoltage ................................ ................................ ................................ .............. 7 
15. Moisture resistance ................................ ................................ ................................ ................. 7 
16. Leakage current and electric strength ................................ ................................ .................... 7 
17. Overload protection of transform ers and associated circuits ................................ ................. 7 
18. Endurance ................................ ................................ ................................ ............................... 7 
19. Abnormal operation ................................ ................................ ................................ ................. 7 
20. Stability and mechanical hazards ................................ ................................ ........................... 8 
21. Mechanical strength ................................ ................................ ................................ ................ 8 
22. Construction ................................ ................................ ................................ ............................ 9 
23. Internal wiring ................................ ................................ ................................ .......................... 9 
24. Components ................................ ................................ ................................ ............................ 9 
25. Supply connection and external flexible cords ................................ ................................ .......9 
26. Terminals for external conductors ................................ ................................ ........................... 9 
27. Provision for earthing ................................ ................................ ................................ .............. 9 
28. Screws and connections ................................ ................................ ................................ .......10 
29. Clearances, creepage distances and solid insulation ................................ .......................... 10 
30. Resistance to heat and fire ................................ ................................ ................................ ...10 
31. Resistance to rust ................................ ................................ ................................ ................. 11 
32. Radiation, toxicity and similar hazards ................................ ................................ ................. 11 
Figure 101 Symbol indicating “no pin inserted” ................................ ................................ ................. 12 
Figure 102 the shape of sample for tear resistance test ................................ ................................ ...12 
Figure 103 Device fo r sparkle ignition test ................................ ................................ ........................ 13 
Figure 103a Template details ................................ ................................ ................................ ............ 14 
Annex ................................ ................................ ................................ ................................ ................. 15 
Annex AA (Normative annex) Testing device for mechanical strength ................................ ............. 15 
Figure AA.1 Testing device for mechanical strength of outer casing materials ................................ 16 
Figure AA.2 details of roller and cylinder ................................ ................................ ........................... 17 
Figure AA.3 details of clamp lever ................................ ................................ ................................ .....17 
Bibliography ................................ ................................ ................................ ................................ .......18 
 
 GB 4706.XX -XXXX  
Introduction  
 
All technical content in this document is mandatory.  
GB4706 means a series of standards on the safety of household and similar electrical 
appliances, and it is divided into two parts:  
The first part: general requirements;  
The second part: particular requirements.  
This document constitutes the second part of GB4706.  
This document includes particular requirements on the safety of household and similar thermal 
storage hand warmers; and it shall be used with GB 4706.1 -2005, General Requirements, Part 
1, Safety of Household and Similar Electrical Appliances.  
This document is shaped by supplements, additions or amendments to GB 4706.1; The part 
indicated with “Applicable” means that the corresponding provisions in  GB 4706.1 also apply 
to this document; the part indicated with “Replacement” means the provisions in this document 
prevail; the part indicated with “Amendment” means the related content of corresponding 
provisions in GB 4706.1 is subject to the amendments  in this document, and the remaining 
content of the said provisions is still applicable; and the part indicated with “Addition” means 
that the supplemented provisions shall be applied besides the corresponding provisions in GB 
4706.1.  
The additions to GB 4706.1 start from No.101.  
This document is proposed by the China National Light Industry Council.  
This document is under the jurisdiction of the National Household Appliance Standardization 
Technical Committee (SAC/TC46).  
The organizations that particip ated in the drafting of this document are: Guangzhou Electric 
Apparatus Research Institute, Chengdu Rainbow Electric (Group) Co., Ltd., Guangdong Midea 
Group Co., Ltd., Foshan Shunde Kebei Intelligent Electric Co., Ltd., Guangdong Shunde 
Entry -Exit Inspect ion And Quarantine Bureau and Guangzhou Vkan Certification & Testing 
Institute.  
The drafters of this document are: Xu Yanrong, Liu Xiangdong, Li Zhengyong, Chen Lushi, Li 
Dening, Lu Dongqi and Zeng Wenli.  
This standard was issued for the first time. .GB 4706.XX -XXXX  
 
Safety of Household and Similar Electrical Appliances  
Particular requirements for thermal -storage hand warmers  
 
1. Scope  
This chapter in GB 4706.1 -2005 is replaced by the following content:  
This document applies to the safety of household and similar purpose thermal -storage hand 
warmers with the rated voltage not exceeding 250  V (hereinafter referred to as “Hand warmer”) 
and similar apparatus.  
This document is also applicable to the control device supplied with apparatus.  
The common hazards that exist when o perating the apparatus mentioned in this document 
may be encountered by every person in or around the house. However, this document 
generally does not cover the following:  
——hazards arising from the use of apparatus by unattended infants or the handicappe d. 
——situations where infants play with apparatus.  
Note 101: Unattended children cannot use the apparatus until they get correct guidance from 
their parents or guardians and are considered to be qualified to use it.  
Note 102: The following conditions nee d attention:  
 Additional requirements may be required for apparatus intended for use in vehicles, ships 
or aircrafts.  
 In many countries, additional requirements have been stipulated for apparatus by the 
national healthcare departments, national labor  protection de partments and similar 
departments;  
Note 103: This document does not apply to the following:  
apparatus intended for use in the special environment where corrosive or explosive gases 
(for example, dust, steam or gas) are often generated;  
 electric blank ets, electric warming pads and similar soft heating apparatus (GB 4706.8);  
 indoor heaters(GB 4706.23);  
 water bed heaters(GB 4706.58);  
 electric heaters intended for breeding and rearing animals (GB 4706.47);  
 electric foot warmers and heating mat s (GB 4706.80);  
 non thermal storage hand warmers;  
 professional apparatus used by patients getting medical care (IEC 60601 -2-35).  
  
2. Normative reference  
This chapter in GB 4706.1 -2005 is applicable.  
  
3. Terms and definitions  
The following terms and def initions are applicable to this document:  
All provisions of this charter in GB 4706.1 -2005, except for the following content, are 
applicable.  
3.1.9 Replacement:  
Normal operation  
The apparatus operates under the following conditions:  
Place a hand warme r horizontally or according to the instructions provided. Connect it to 
power supply. T he thermal storage process will end when the device which controls the 
temperature of the thermal storage kernel cuts off the power supply for all electric heating 
compo nents for the first time.  
 GB 4706.XX -XXXX  
 
3.101  
Hand warmer  
An apparatus which is held by the user to warm his/her hands by converting electricity to heat.  
3.102  
Thermal storage hand warmer  
A hand warmer which stores the heat converted from electricity in a kernel and releases heat 
in a natural way. This kind of hand warmer is disconnected with the power supply when it is 
held by the user to warm his/her hands.  
3.103  
Hard hand warmer  
A hand warmer with the hard outer casing.  
3.104  
Soft hand warmer  
A hand warmer with t he soft outer casing.  
4. General requirements  
This chapter in GB 4706.1 -2005 is applicable.  
5. General conditions of tests  
All provisions of this chapter in GB 4706.1 -2005, except for the following content, are 
applicable:  
5.2 Addition:  
According to test requi rements, add more samples required by the test.  
Add one sample for conducting the test in 21.101.  
For soft hand warmers, the outer casing material with the dimensions of 1 200  mm×1 200  mm 
is required to conduct the tests in 21.102, 21.103 and 30.101.  
5.3 Addition:  
For soft hand warmers, the test in 21.104 shall be conducted after the test in Chapter 29.  
5.5 Addition:  
If an apparatus has a removable envelope, the test shall be conducted under the condition s 
with or without envelope, whichever is unfavorabl e. If an apparatus is required to use with 
envelope according to the instructions provided, the test shall be done with envelope.  
If the electric heating components are removable, they shall be moved to the most unfavorable  
positions for the test.  
5.7 Am endment:  
The environment temperature of tests is 23  ±2.  
6. Classification  
All provisions of this chapter in GB 4706.1 -2005, except for the following content, are 
applicable.  
6.1 Amendment:  
The apparatus shall belong to the type II or III category. The rated voltage of Type III 
apparatus shall not exceed 24V.  
  
7. Marking and instructions  
All provisions of this chapter in GB 4706.1 -2005, except for the following content, are 
applicable:  
7.1 Amendment:  
The apparatus shall be marked with the rated power i nput.  
Addition:  
The apparatus shall be marked with the following:  GB 4706.XX -XXXX  
 
—— No service is allowed when the apparatus is live.  
Hard hand warmers shall be marked with the following:  
—— the symbol indicating “Do not cover” or the graphical symbol IEC60417 -5641( DB
2002 -10).  
Soft hand warmers shall be marked with the following:  
—— the symbol indicating “No pin inserted” or the symbol indicated in Figure 101.  
7.12 Addition:  
The instructions shall contain the following:  
Important: Keep it in a safe place  for fu ture use; it can not be used by depende nt people, 
infants or people insensitive to heat.  
The instructions shall contain the following:  
—— The apparatus shall be used with the supporting connector;  
—— If the apparatus is marked with the symbol indicating “Do not cover”, its meaning shall be 
explained as follows;  
—— Place the apparatus out of children’s reach when it is connected to the mains for thermal 
preservation.  
—— Leave the apparatus to cool down to room temperature before storing it.  
—— Do not place  any objects on the apparatus when it is being connected to the mains or 
during storage.  
—— Check the apparatus for any signs of abrasion or damage from time to time; in case of 
such signs, please do not use it.  
The instructions of soft hand warmers shall  contain the following:  
—— Do not flush it with water;  
—— Do not touch sharp or pointed objects;  
—— Prevent it from falling on the ground and do not put a heavy load on it;  
—— Do not wipe it with gasoline, toluene or other strong solvents.  
The instructio ns shall specify that the apparatus is not suitable for use by children unless their 
parents or guardians have set it beforehand, or have informed children of the usage in detail.  
7.14 Addition:  
The height of Figure 101 and the graphic symbol of “Do not cover” shall be 15 mm at least.  
The font height of “Important” and its content shall be 6 mm at least.  
Conformity is subject to measurement.  
  
8. Protection against access to live parts  
This chapter in GB 4706.1 -2005 is applicable.  
 
9. Starting of motor -oper ated appliances  
This chapter in GB 4706.1 -2005 is not applicable.  
  
10. Power input and current  
This chapter in GB 4706.1 -2005 is applicable.  
  
11. Heating  
All provisions of this chapter in GB 4706.1 -2005, except for the following content, are 
applicable:  
11.2 Amendment:  
Put a hand warmer at the test corner under normal operation conditions, with it being close to 
one side wall and away from the other.  
11.8 Addition:  
The temperature rise of the surface of hand warmer, the wall of the test corner and the base GB 4706.XX -XXXX  
 
plate shall not exceed the value indicated in Table 101.  
Table 101 Max. normal temperature rise  
Surface  
 Temperature rise  
K 
Surface of hand warmer  75 
Wall of test corner and base plate  7 
12. Void  
13. Leakage current and electric strength at operating temperatu re 
This chapter in GB 4706.1 -2005 is applicable.  
 
14. Transient  overvoltage  
  This chapter in GB 4706.1 -2005 is applicable.  
15. Moisture resistance  
This chapter in GB 4706.1 -2005 is applicable.  
  
16. Leakage current and electric strength  
This chapter in GB 4706.1 -2005 is applicable.  
17. Overload protection of transformers and associated circuits  
This chapter in GB 4706.1 -2005 is applicable.  
  
18. Endurance  
This chapter in GB 4706.1 -2005 is not applicable.  
19. Abnormal operation  
All provisions of this chapter in GB 4706.1 -2005, except for the following content, are 
applicable:  
19.2 Addition:  
Put a hand warmer at the test corner under normal operation conditions, with it being close to 
one side wall and away from the other. Place one piece of heat insulation material which i s 36 
mm thickness under the hand warmer as a pad, and cover the hand warmer completely or 
partly with another piece of heat insulation material with the same thickness, whichever is 
unfavorable .  
For those soft hand warmers that require users to add liquid  by themselves, test them with a 
full load or no load, whichever is unfavorable .  
The heat insulation material comprises the following content:  
Apertured polyether;  
Aperture number: 18
 /cm; 
Specified mass: 30kg/m3
 %; 
Hardness: 120N - 170N at 40% of the impress measured in line with GB/T 10807(idt ISO 
2493).  
  
19.13 Addition:  
During test period, the temperature rise of the hand warmer surface contacting heat insulation GB 4706.XX -XXXX  
 
material shall not exceed 155K.  
  
20. Stability and mechanical hazards  
This chapter in G B 4706.1 -2005 is applicable.  
  
21. Mechanical strength  
All provisions of this chapter in GB 4706.1 -2005, except for the following content, are 
applicable:  
21.1 Addition:  
Hand warmers are also required to withstand the test in 21.101.  
Soft hand warmers are a lso required to withstand the tests in 21.102, 21.103 and 21.104.  
After such tests, the apparatus shall be free of the following:  
—— damage of the outer casing which may lead to nonconformity with the requirements in 
this document;  
—— breakage of electri c heating components;  
—— damage of structure joint, or breakage of adhesion or welding points which may lead to 
nonconformity with the requirements in this document;  
—— detachment of input socket of apparatus;  
—— disconnect ion or breakage of electric conne ction.  
Addition:  
21.101 Take a hand warmer, position  it downwards at the most unfavorable position, and allow 
it to fall freely from the height of 900  mm to a fixed horizontal hardwood board with thickness of 
about 20  mm. Conduct this test 3 times. The f lexible power cord of the hand warmer shall be 
removed from the input socket of the apparatus, because the cord is not within the scope of 
this test.  
After this test, the hand warmer shall be free of such damages which may lead to 
nonconformity with the r equirements of this document. If the hand warmer can still continue to 
operate, it shall be subject to the test in Chapter 11.  
21.102 For soft hand warmers, attach the outer casing material of 1 000  mm×1 000  mm tightly 
to the device described in Annex AA.   
The outer casing material is pulled by a drive bar and the drive gear works at the speed of 33 
cycles / min.  
Attach one end of the outer casing material to the drive bar for 1000 -cycle rotation, and then 
rotate it 90º for another 1000 -cycle rotation.  
Note: this test is conducted under the condition where the roller is close to the same surface 
with the outer casing material.  
21.103 The outer casing material for soft hand warmers shall provide good tear resistance 
under normal operation conditions.  
Conformity is subject to the following test.  
Put five samples of outer casing material as indicated in Figure 102 under the environment 
where temperature is 23 ±2. 
Fix the short side of each sample completely on the clamps of a stretching machine, with the 
sample and clamp on the same plane. Make the clamps take apart at the speed of 50  mm/min 
until the sample is torn up, and measure the max. breaking load.  
The average value of breaking load for five samples shall not be less than 12.5 N.  
21.104 Soft hand warmers shall withstand the crushing test.  
Conformity is subject to the following test.  
Support a hand warmer completely with a piece of plywood with a thickness of about 20  mm, 
place a piece of plywood of 300  mm×300  mm×20 mm on the top surface of the hand warmer 
at the most unfavorable  position, and place a weight of 80 kg on the plywood for 5 min.  
After the test, the hand warmer shall have no leakage of l iquid or breakage.  
Note: the edges of the plywood shall be round and smooth.  GB 4706.XX -XXXX  
 
22. Construction  
All provisions of this charter in GB 4706.1 -2005, except for the following content, are 
applicable.  
22.7 Amendment:  
In terms of structure, soft hand warmers shall be equipped with the protection device which 
can prevent over -high pressure inside the warmer during it is connected to the mains.  
Through the visual inspection, if the apparatus is installed without such over -high pressure 
protection device, the apparatu s is identified as failure to meet the requirement; if that device is 
available, conformity will be subject to the following test:  
Under the conditions specified in Chapter 11, a hand warmer is input the power that is 1.15 
times of the rated power input.  
All thermal controllers shall occur short circuit at the same time.  
Leave the hand warmer operate until the over -high pressure protection device works.  
After the test, the hand warmer shall have no leakage of liquid or breakage.  
Addition:  
22.101 The st ructure of hand warmer shall hold the electric heating components and internal 
wiring at their pre -configured positions.  
Conformity is subject to the visual inspection.  
22.102 For soft hand warmers, except for Type III apparatus, the insulation of electr ic heating 
components and internal wiring shall be integrated with conductors.  
Conformity is subject to the visual inspection.  
22.103 No burrs that may damage soft materials shall exist in the internal structure or at 
connection terminal of the soft hand  warmer.  
Conformity is subject to the visual inspection.  
  
23. Internal wiring  
This chapter in GB 4706.1 -2005 is applicable.  
  
24. Components  
All provisions of this chapter in GB 4706.1 -2005, except for the following content, are 
applicable:  
Addition:  
24.1.4 Amendment:  
The working cycle -times of the self -resetting thermal cut -out is 10 ,000.  
24.101 For soft hand warmers, at least one thermal cut -out which limits the temperature of 
thermal storage kernel is of a non self -resetting type.  
Conformity is subject to the visual inspection.  
25. Supply connection and external flexible cords  
This chapter in GB 4706.1 -2005 is applicable.  
 
26. Terminals for external conductors  
This chapter in GB 4706.1 -2005 is applicable.  
 
27. Provision for earthing  
This chapter in GB 4706.1 -2005  is not applicable.  GB 4706.XX -XXXX  
 
28. Screws and connections  
This chapter in GB 4706.1 -2005 is applicable.  
29. Clearances, creepage distances and solid insulation  
This chapter in GB 4706.1 -2005 is applicable.  
30. Resistance to heat and fire  
All provisions of this chapter in GB 4 706.1 -2005, except for the following content, are 
applicable:  
30.1 Addition:  
This requirement is not applicable to soft hand warmers.  
30.2 Addition:  
This requirement is not applicable to soft hand warmers.  
Addition:  
30.101 Soft material shall have fl ame resistance.  
Conformity is subject to the following spark ignition test.  
Cut off six samples from the outer casing material, making each with the dimensions of 100  
mm×200 mm, and no two samples appear on the same longitude or latitude line. If it fail s, no 
more than two samples appear on the same line when samples are selected.  
If the outer casing material is inseparable, use the double layer material for test ing.  
The test device, as shown in Figure 103, has two copper electrodes with a diameter of 3  mm, 
which are installed on an insulated base plate through two copper rods, making their axes 
align each other. On the base plate, there also stands a platform with the dimensions of 100  
mm×100 mm  which is made of insulation material. This platform is fou nd between the two 
copper rods and equipped with a mechanism designed to adjust the platform height.  
Fix one electrode and leave the other removable, so that the sample can be inserted. The 
fixed electrode has an angle of 45o on its pointed end. The farth est point on the electrode away 
from the copper rod shall be on the pointed end of the electrode and its distance away from 
the platform shall be about 3  mm. The removable electrode has a flat end.  
Place the lower element of one piece of hardwood template , as shown in Details A of Figure 
103a , at the specified position of the adjustable platform.  
Put the testing device, including the upper element of the template , as shown in Details B of 
Figure 103a, into a heating chamber, which has a door with an obser vation  window , where 
natural convection circulation of air can be achieved. Make series connection of the electrode , 
and one adjustable non -inductive resistance, to a power supply with sinusoidal rated output 
voltage of 10kV . The power supply feature s that output voltage does not decrease by above 
100V when the current flow is 1 mA.  
Raise  the temperature of the heating chamber to 65 ±2. Then short circuit  the electrode, 
and adjust resistance to contribute to 1 mA current flow. Disconnect the power supply,  and 
leave the sample in the heating chamber for 3 hours.  
Do not take the testing device from the heating chamber. Take away the removable electrode, 
and pull one sample to the fixed electrode so that this electrode is at the centr e of the space 
occupied by electric heating components. Adjust the sample to make one of its ends 
approximately parallel to the edge of the adjustable platform, and then insert the removable 
electrode into the other end of electric heating components, and get it fixed. The distan ce 
between two electrodes is 6.0  mm ±0.1 mm . Make the sample level and p osition  the upper 
element of the template. Close the door of the heating chamber for 5 min utes to stabilize  the 
temperature.  
Then connect power supply and allow sparkle to exist betwee n both electrodes for 2 min utes. 
If the sample is ignited, the time shall be recorded from the moment of power connection to 
when sparkle reaches the inner edge of the template. If the burning duration of the fibers on 
the surface does not last 3  seconds , it can be omitted. If the sample is not ignited, the time is GB 4706.XX -XXXX  
 
recorded as 120  seconds .  
After that, take out the sample and put the other side of the sample upwards between both 
electrodes, to make the opposite end experience the test.  
The test above is re peated for the other 5 samples.  
If any time record is less than 30 s econds , all tests are required to be repeated for a second 
group of 6 samples. Under such condition s, the time record of samples shall not less than 30  
seconds .  
Calculate the average of 12 records . It should not be  less than 80  seconds . Ignore all values 
where the difference with the average is greater than 30 s econds . If necessary, calculate the 
average of the remaining records again.  
 
31. Resistance to rust  
This chapter in GB 4706.1 -2005 i s applicable.  
  
32. Radiation, toxicity and similar hazards  
This chapter in GB 4706.1 -2005 is applicable.  
 GB 4706.XX -XXXX  
 
 
                    
    
  
Figure 101 Symbol indicating “no pin inserted”  
  
  
  
   
                                                                       Unit: mm  
  
A: pull direction;  
B: striation direction.  
 
Figure 102 the shape of sample for tear resistance test  
  
  GB 4706.XX -XXXX  
 
  
 
 
 
 
A: Adjustable platform;  
B: lower template (see Details A of Figure 103 a);  
C: fixed electrode;  
D: upper template(see Details B  of Figure 103a);  
E: rod;  
F: removable electrode;  
G: base plate.  
 
 
 
 
 
Figure 103 Device for sparkle ignition test  
 
 
 
 GB 4706.XX -XXXX  
 
   
Details A —— lower template 
   
   
Details B —— upper template  
Unit: mm  
Note: the mass of upper template is 100 g, which can be ach ieved by trimming its thickness.  
Figure 103a Template details  
 GB 4706.XX -XXXX  
 
 
Annex  
  
All provisions of the annex in GB 4706.1 -2005, except for the following content, are applicable.  
  
Annex AA  (Normative annex)  Testing device for mechanical strength  
  
The testing de vice, as shown as Figure AA.1, features a rotating roller with a diameter of 160 
mm, whose length is large enough to accommodate the total length of outer casing material. 
Cut open a solid rubber ball with the diameter of 60 mm ±2.5 mm and Rockwell hardness  of 40 
– 50. Place  them on the roller and make them protrude 25 mm above the roller. These 
semi -spheres are arranged in six rows evenly around the roller’s circumference, 320 mm apart 
from each other. Each semi -sphere is located at the middle position of a  pair of semi -spheres 
of a neighbo uring row (see Figure AA.2). This roller can rotate around its axis.  
Below the roller, there is a bar with square cross -section and side length of 25 mm ×25 mm. It 
is constructed so that it can be installed on a guide rail  and can rotate in the loader , which can 
move upwards or downwards freely. The total mass of the bar and loader can be adjusted by 
adding weights to the loader.  
There are some smooth hardwood cylinders with a diameter of 65 mm and a length of 140 mm 
above  the roller, and each cylinder is fixed with a pair of arms. The cylinder arms are 160 mm 
away from the axis of the cylinder , around which the cylinder arms rotate. The position of these 
cylinders shall allow each semi -sphere to pass underneath the centr e of a cylinder. The pivot 
bar is positioned so that the axis of the cylinder arms can form an angle of 25 °to horizontal 
when the cylinders contact the top of the roller. The force applied on the roller by each cylinder 
is 5.1  N.  
A gear with a diameter of 2 30 mm is securely fixed at both ends of the supporting axis of the 
roller. A circular chain drives the drive bar around the gear, and goes through the lowest 
position of the bar with a square cross -section.  
Attach the clamp lever to the drive bar by using  the screw with a diameter of 3.5 mm (as 
shown in Figure AA.3). On the edge of the clamp lever, there are steel swivels attached.  
Tightly connect the total length of the outer casing material to the steel wire swivels with 
clamps and an adjustable woven b elt. Then let it pass around the roller, and go underneath 
the bar with square cross -section to be clamped with the other end of the woven belt. The 
outer casing material and woven belt form a continuous belt. It is pulled by adding weights to 
the loader, so that the total mass of the bar assembly and the loader enables the connection 
side of the outer casing material to bear the weight of 6 kg. Adjust the woven belt to increase 
by 50 mm from the non -operation position of the bar with the square cross -section and the 
loader, and then the pull force borne  by the woven belt shall not be changed. The woven belt 
shall be positioned so that they can pass through between the semi -spheres on the roller.  
Note 1: Sufficient woven belts shall be used to prevent wrinkles on the outer casing 
material.  
Note 2: All flexible power cords and the connection types of the drive bar shall not affect 
the test result s. 
Note 3: A device shall be installed, which is desig ned to raise the cylinders when the drive 
bar passes through the roller, avoiding the damage of testing devices.  
Note 4: Drive bars shall be driven separately. Both the roller and the bar with the square 
cross -section are driven to rotate by the outer casi ng material when it goes over them.  
  GB 4706.XX -XXXX  
 
 
A: drive chain; B: clamp lever; C: drive bar; D: self -adjusting axis; E: locking cylinder; F: cylinder arm;  
G: gear; H: drive bar; I: bar with square cross -section; J: outer casing material in test  
Figure AA.1 Testi ng device for mechanical strength of outer casing materials  
 GB 4706.XX -XXXX  
 
   
A: cylinders;  
B: cylinder arm;  
C: solid rubber ball.  
 
Figure AA.2 details of roller and cylinder  
  
   
                                                                  Unit: mm  
A: steel pi pe with the diameter of 25 mm and wall thickness of 1.6 mm;  
B: steel swivel with the diameter of 2.5 mm;  
C: hinge welded on the steel pipe.  
  
Figure AA.3 details of clamp lever  GB 4706.XX -XXXX  
 
 
Bibliography  
  
  
All provisions of the bibliography in GB 4706.1 -2005, exce pt for the following content, are 
applicable:  
Addition:  
GB 4706.8 -XXXX (idt IEC 60335 -2-17:2006) Safety of Household and Similar Electrical 
Appliances – Particular Requirements for Electric Blankets, Electric Warming Pads and Similar 
Soft Heating Apparat us 
GB 4706.23 (idt IEC 60335 -2-30) Safety of Household and Similar Electrical Appliances – 
Particular Requirements for Indoor Heaters  
GB 4706.44 (idt IEC 60335 -2-61) Safety of Household and Similar Electrical Appliances – 
Particular Requirements for Therma l-Storage Indoor Heaters  
GB4706.80 (idt IEC 60335 -2-81) Safety of Household and Similar Electrical Appliances – 
Particular Requirements for Electric Foot Warmers and Heating Mats