Ordinance on Industrial Safety and Health
Ministry of Labour Ordinance No. 32 of September 30, 1972

Latest Amendments:
Ministry of Health, Labour and Welfare Ordinance No. 47 of March 30, 2007
In Japanese

Part II Safety Standards

Chapter V Prevention of Dangers Due to Electricity

Section 1 Electric Machine and Appliance

Article 329 (Enclosure, etc., for Electric Machine and Appliance)

• (1) The employer shall, as regards live parts of electric machine and appliance (excluding the portions of electric machine and appliance which are inevitable to be exposed for the purpose of their use such as heating unit of electric heaters, the welding rods of resistance welding machines) which is liable to cause danger of electric shocks to workers when they contact (including contact via an electric conductor; hereinafter the same shall apply in this Chapter) or come in proximity to these parts during work or passage, install enclosures or insulating covers in order to prevent electric shocks. However, this shall not apply to the electric machine and appliance which are installed in an enclosed place such as a switchboard room and substation room where the employer prohibited persons other than those who are engaged in the work set forth in item (iv) of Article 36 (hereinafter referred to as “electrician”) from entering, or installed on detached place such as a pole and a tower where there is no possibility that persons other than electrician will come in proximity to them.

Article 330 (Guard for a Portable Lamp, etc.)

• (1) The employer shall install a guard for portable lamps connected with movable electric wire, suspended lamps, etc., connected with makeshift installed wiring or movable electric wire, in order to prevent the danger of electric shocks by contacting the bayonet cap, and the danger due to broken electric bulbs.
• (2) The employer shall conform the guard set forth in the preceding paragraph to the following provisions:
  • (i) To have the structure that prevents hands from easily contacting the exposed portion of the bayonet cap of the electric bulbs.
  • (ii) To be made of the materials which are not easily broken or deformed.

Article 331 (Holders for Welding Rod, etc.)

• (1) The employer shall, as regards holders for welding rod, etc., used in work such as arc welding, etc. (excluding automatic welding), not use them unless those which conform to the standards described in the Japanese Industrial Standard C 9302 (Welding rod Holders), or those which have same insulating effect or heat resistance as this Standard or better.

Article 332 (Automatic Voltage Reducing Device for A.C. Welding Machines)

• (1) The employer shall, when carrying out alternative current arc welding, etc. (excluding automatic welding) at places surrounded by electric conductors which are very small in space, such as inside of a double-bottom or peak tank of a vessel, of a drum or dome of a boiler, or at the place in height of 2 m or higher where it is liable to cause dangers to workers due to fall and that is liable to workers contact grounding materials with high conductivity of steel frame, etc., use an automatic voltage reducing device for alternative current arc welding machines.

Article 333 (Prevention of Electric Shocks Due to Leakage of Electricity)

• (1) The employer shall, as regards machines or appliance equipped with motor (hereinafter referred to as “motor-driven appliance”) which are of the movable or portable type, those have voltage to ground exceeding 150 V , or those used at places where they are wetted with liquids having high electric conductivity such as water, or at places where electric conductivity is high, such as on an iron plate, a steel frame, or a surface plate, connect an earth-leakage circuit breaker for preventing electric shocks that conforming the rating of the said circuit, and having good sensitivity and the function to reliably work in order to prevent danger of electric shocks due to the leakage of electricity to the electric circuit to which motor-driven appliance are connected.
• (2) The employer shall, when it is difficult to take the measures prescribed by the preceding paragraph, use by grounding the metal portions of the outer frame of motor-driven appliance , metal covers of motors, prescribed as follows:
  • (i) To connect the said metal portions to a grounding pole by any of the following method:
    • (a) The connecting method to a grounding pole by using a movable cable with a core exclusively used for a grounding line and a connecting device with terminal exclusively used for a grounding terminal.
    • (b) The method connecting a grounding line attached to a movable electric cable and the grounding terminal installed at the location adjacent to a power source consent of a motor-driven apparatus.
  • (ii) When the method set forth in (a) of the preceding item is to used, take measures to prevent confusing the grounding conductor and an electric conductor connected to the electrical circuit, and the grounding terminal and a terminal connected to the electrical circuit.
  • (iii) To securely connect the grounding pole with the ground by the method such as burying it in the ground to a sufficient depth.

Article 334 (Exemptions)

• (1) The provisions of the preceding Article shall not apply to motor-driven appliance, which falling under any of the following each item:
  • (i) Motor-driven appliance use by connecting with an electrical circuit of a non-grounding system (limited to those for which the secondary voltage of the insulated transformer provided in the circuit on the power source side of the motor-driven appliance is 300 V or less, and which the electrical circuit on the load side of the insulated transformer is not grounded).
  • (ii) Motor-driven appliance used on an insulating platform.
  • (iii) Motor-driven appliance of a double insulation structure attached the indication set forth in the paragraph (1) of Article 10 of the Electric Appliances Materials Act (Act No.234 of 1961) of specified electric appliances set forth in the same Act.

Article 335 (Illumination over the Operation Portions of Electric Machine and Appliance)

• (1) The employer shall, when operating electric machine and appliance, maintain necessary illumination over the operation portions of the said electric machine and appliance in order to prevent dangers of electric shocks or dangers due to an operational error.

Section 2 Wiring and Movable electric cables

Article 336 (Insulating Coating of Wiring, etc.)

• (1) The employer shall, as regards wirings which workers contact or may contact during work or passage and which have insulating coating (excluding those which only electrician contact or may contact in work set forth in item (iv) of Article 36), or movable electric cables, take measures for preventing the danger of electric shocks due to damage or aging of the insulating coating.

Article 337 (Covering or Armor of Movable electric cables, etc.)

• (1) The employer shall, as regards movable electric cables or their connecting tools used at places where are wetted with water or other liquids having high conductivity and which workers may contact during work or passage, not use them unless the covering or armor of the said movable electric cables or their connecting tools have an insulating effect against the said liquids having high conductivity.

Article 338 (Makeshift Wiring, etc.)

• (1) The employer shall not use makeshift wiring or movable electric cables on the sides of passages. However, this shall not apply to when using the said wiring or movable electric cables in a condition where there is no possibility that the insulating coating of the said wiring or movable electric cables may be damaged due to a vehicle and other things passes over the said wiring or movable electric wires.

Section 3 Power Cut Operation

Article 339 (Measures in the Case of Power CutWork)

• (1) The employer shall, when carrying out an electric work such as installation, checkup, repairing or painting of an electrical circuit or its support while the said circuit is opened, take the following measures for the said electrical circuit after the said electrical circuit is opened. This provision shall also apply to the case of carrying out an electric work such as installation, checkup, repairing or painting of an electrical circuit or its support close to the said electrical circuit or work such as the construction, dismantlement, checkup, repairing or painting of a structure close to the said electrical circuit (excluding the support of an electrical circuit, hereinafter the same shall apply in this Chapter):
  • (i) To lock the switch used for circuit opening during work, or indicate necessary matters relating to prohibition of electric charge, or place a watcher.
  • (ii) As regards the opened circuit are equipped with a power cable, power capacitor, etc., and are liable to cause danger due to residual electric charge, to discharge the said residual charge completely by a safe method.
  • (iii) As regards the opened circuit are in high voltage or extra-high voltage, to confirm the power cut with voltage detector, and short circuit to ground the said circuit securely with a appliance for short circuit to ground to prevent the danger of electric shocks due to erroneous turning on the electricity, confusion with other circuits or induction from other circuits.
• (2) The employer shall, when intending to turning on the opened circuit during work set forth in the preceding paragraph or when the said work is finished, not turn on the electricity unless otherwise having confirmed that it is unlikely to cause danger of electric shocks to the worker engaging the said work and the appliance for short circuit to ground has been removed.

Article 340 (Opened Circuit of Disconnector, etc.)

• (1) The employer shall, when opening a switch such as a disconnector and line switchfor high voltage or extra-high voltage electrical circuit that is not for breaking load current, in order to prevent an operational error of the said switch, have workers engaged in the said operation confirm that the said electric circuit is on no load using a pilot lamp indicating that such electric circuit is on no load, a tablet for identifying the said electrical circuit, etc. However, this shall not apply to when a locking device is provided for the said switch not to allow circuit opening unless the said electrical circuit is not load.

Section 4 Live Line Work and Work Close to Live Line

Article 341 (High-Voltage Live Line Work)

• (1) The employer shall, in the case of carrying out the work handling a charged circuit of high voltage, such as checkup and repair of the said circuits, and when it is liable to cause danger of electric shocks to the worker engaging in the said work, take measure falling under any of the following each item:
  • (i) To have a worker wear personal insulating protective equipment, and install an insulating device to the portions of such charged electrical circuit other than the portion handled by workers where is liable to cause danger of electric shock when workers contact or close to the portions.
  • (ii) To have a worker use live line work instruments.
  • (iii) To have a worker use live line work equipment. In this case, the danger of electric shocks due to the body of a worker or an electric conductor handled by workers such as a metal tool and material (hereinafter referred to as “body, etc.”) contacts or close to objects with different voltage from that of charge circuit actually handled by workers shall be eliminated.
• (2) A worker shall, in the work set forth in the preceding paragraph, when having been instructed to wear personal insulating protective equipment, install an insulating device, and use live line work instruments or live line work equipment by the employer, wear, install, or use them respectively.

Article 342 (Work Close to High-Voltage Live Lines)

• (1) The employer shall, in the case where carrying out the electric workinstalling, inspecting, repairing, painting, etc., of an electrical circuit or its supports, and when it is liable to cause danger of electric shock to the worker engaging in the said work due to contacting a high-voltage charged circuit, or approaching the said electrical circuit within 30 cm above the head or within 60 cm from the side of the body or below the feet, install an insulating device for the said charged circuit. However, this shall not apply to the case of having the worker engaging in the said work wear personal insulating protective equipment, and when it is unlikely to cause danger of electric shock to the parts of the body other than those wearing the said personal insulating protective equipment due to contact or approach the said charged electrical circuits.
• (2) A worker shall, when having been instructed to provide an insulating device or wear personal insulating protective equipment by the employer in the work set forth in the preceding paragraph, provide and wear them respectively.

Article 343 (Install of an Insulating Device, etc.)

• (1) The employer shall, when having workers carry out work installing or removing an insulating device in the case set forth in the preceding two Articles, have the worker engaging in the said work wear personal insulating protective equipment or have them use live line work instruments or live line work equipment.
• (2) A worker shall, in the work set forth in the preceding paragraph, when having been instructed to wear protective equipment or use live line work instruments or live line work equipment by the employer, wear or use them respectively.

Article 344 (Extra-High-Voltage Live Line Work)

• (1) The employer shall, in the case of carrying out electric work such as checkup, repairing and cleaning of a extra-high-voltage charged circuits or their supporting insulators, and when it is liable to cause danger of electric shock to the worker engaging in the said work, take measure falling under any of the following each item:
  • (i) To have a worker use live line work instruments. In this case, for the body, etc., approach limit listed in the right column of the following table shall be maintained corresponding to the working voltage of charged circuit listed in the left column of the same table.

    Working voltage of charged electric circuit (kV)	Minimum allowable proximity (cm)
    22 or less	20
    Exceeding 22 but 33 or less	30
    Exceeding 33 but 66 or less	50
    Exceeding 66 but 77 or less	60
    Exceeding 77 but 110 or less	90
    Exceeding 110 but 154 or less	120
    Exceeding 154 but 187 or less	140
    Exceeding 187 but 220 or less	160
    Exceeding 220	200

  • (ii) To have a worker use live line work equipments. In this case, the danger of electric shocks due to the body, etc., contacts or close to a substance having an electric potential different from the electric potential of the charged electric circuit or its supporting insulators handled by workers shall be eliminated.
• (2) A worker shall, when having been instructed to use a live line work instrument or live line work equipment in the case set forth in the preceding paragraph, use it.

Article 345 (Work Close to Extra-High-Voltage Live Line)

• (1) The employer shall, in the case of carrying out electric work such as checkup, repairing, painting and cleaning of an electric circuit or its supports (excluding supporting insulators for extra-high-voltage charged circuits) , and when it is liable to cause danger of electric shock to the worker engaging in the said work due to close to a extra-high-voltage charged circuit, take measure falling under any of the following each item:
  • (i) To have a worker use live line work equipment.
  • (ii) To have body, etc., keep approach limit to the charged circuit as prescribed in item (i) of paragraph (1) of the preceding Article. In this case, provide a sign, etc., at a readily visible location where the minimum allowable proximity may be maintained, or to place a watcher and have the watcher watch the work .
• (2) A worker shall, in the work set forth in the preceding paragraph, when having been instructed to wear personal insulating protective equipment or use live line work equipment by the employer, wear or use them respectively.

Article 346 (Low Voltage Live Line Work)

• (1) The employer shall, in the case of carrying out work handling a low voltage charged circuit, such as checkup and repairing of the said circuit, and when it is liable to cause danger of electric shocks to the worker engaging in the said work, have the said workers wear personal insulating protective equipment or have them use live line work instruments.
• (2) A worker shall, in the work set forth in the preceding paragraph, when having been instructed to wear personal insulating protective equipment or use live line work instruments by the employer, wear, or use them respectively.

Article 347 (Operations Close to Low-Voltage Live Line)

• (1) The employer shall, in the case of carrying out electric work such as installing, checkup, repairing, and painting of an electrical circuit or its supports at a place close to a low-voltage charged electric circuit, and when it is liable to cause danger of electric shock tothe worker engaging in the said work due to contacting the said charged circuit, install an insulating device for the said charged electrical circuit. However, this shall not apply to the case of having the worker engaging in the said work wear personal insulating protective equipment, and when the parts of the body, etc., other than those wearing the said personal insulating protective equipment are unlikely to cause contacting the said charged electrical circuit.
• (2) The employer shall, in the case described in the preceding paragraph, and when having workers carry out work installing or removing an insulating device, have the worker engaging in the said work wear personal insulating protective equipment or have them use live line work instruments.
• (3) A worker shall, in the work set forth in the preceding two paragraphs, and when having been instructed to install an insulating device, wear personal insulating protective equipment, or use live line work instruments by the employer, install, wear, or use them respectively.

Article 348 (Personal Insulating Protective Equipment, etc.)

• (1) The employer shall, as regards personal insulating protective equipment, etc., listed in following each item, use those of the type, materials and size suitable for the purpose of use respectively:
  • (i) The personal insulating protective equipment set forth in Article 341 to 343.
  • (ii) The insulating device set forth in Article 341 to 342.
  • (iii) The live line work equipment set forth in Article 341 and 343 to 345.
  • (iv) The live line work instruments set forth in Article 341, 343 and 344.
  • (v) The personal insulating protective equipment and the live line work instruments set forth in Article 346 and 347 and an insulating device set forth in Article 347.
• (2) The employer shall, as regards personal insulating protective equipment, live line work instruments and an insulating device listed in item (v) of the preceding paragraph, which are used for a charged circuit of 750 V or less for direct current or of 300 V for alternative current or less, use those having an insulating effect corresponding to the voltage of the said charged circuit.

Article 349 (Prevention of Electric Shocks in the Case of the Work for the Construction of Structures, etc.)

• (1) The employer shall, in the case where carrying out the works such as constructing, dismantling, checkup, repairing,and painting of a structure or the work associated with them, or the work using a pile driver, pile drawer, mobile crane, etc., at a place close to overhead wires or charged circuits of electric machine and appliance, and when it is liable to cause danger of electric shocks to the worker engaging in the said works due to the workers' body, etc., contact or close to the said charged circuits during work or passage, take measure falling under any of the following each item:
  • (i) To move the said charged circuits to other places.
  • (ii) To install an enclosure to prevent the danger of electric shock.
  • (iii) To provide the charged circuits with personal insulating protective equipment.
  • (iv) When taking measures falling under the preceding three items are extremely difficult, place a watcher and have the said watcher oversee the work.

Section 5 Management

Article 350 (Instruction, etc., in the Case of an Electric Work)

• (1) The employer shall, when carrying out the work set forth in Article 339, paragraph (1) of Article 341, paragraph (1) of Article 342, paragraph (1) of Article 344 or paragraph (1) of Article 345, make the period of the work, the contents of the work and electric circuits handled, and the system of electric circuits close to the said electrical circuits known to the worker engaging in the said work, and designate a leader of the work and have the said leader carry out the following matters:
  • (i) To make the method and procedure of the work known to the workers in advance, and supervise the work directly.
  • (ii) When carrying out the work set forth in paragraph (1) of Article 345 by taking the measures set forth in item (ii) of the same paragraph, to instruct the commencement of the work after having confirmed installation of a sign, etc., or arrangement of a watcher.
  • (iii) When carrying out work after the electrical circuit is opened, to instruct the commencement of the work after having confirmed the state of power cut of the said electrical circuit, the locked switch used for such circuit opening, indication of matters necessary to prohibit electric charge, placement of a watcher, and the state of fitting of appliance for short circuit to ground after the electric circuit has been opened.

Article 351 (Periodical Self-inspections of Personal Insulating Protective Equipment, etc.)

• (1) The employer shall, as regards personal insulating protective equipment, etc., listed in each item of paragraph (1) of Article 348 (for those listed in item (v) of the same paragraph, limited to those used for an charged circuit of low voltage exceeding 300 V in alternative current; hereinafter the same shall apply in this Article), carry out self-inspections for the insulating performance, periodically once every period within six months. However, this shall not apply to the non-use period of personal insulating protective equipment, etc., which is not used for a period exceeding six months.
• (2) The employer shall, as regards the personal insulating protective equipment, etc., set forth in the proviso of the preceding paragraph, carry out self-inspection for the insulating performance before resuming the use.
• (3) The employer shall, when having found any abnormality in the said personal insulating protective equipment, etc., as a result of the self-inspection set forth in paragraph (1) or (2), not use them unless otherwise having repaired or taken other necessary measures.
• (4) The employer shall, when having carried out the self-inspections set forth in paragraph (1) or (2), record the following matters and preserve the records for three years:
  • (i) The date of the inspection
  • (ii) The method of the inspection
  • (iii) The parts of a machine inspected
  • (iv) The results of the inspection
  • (v) The name of the person who has carried out the inspection
  • (vi) When measures such as repair have been taken based on the result of the inspection, their contents.

Article 352 (Checkup, etc., Before Use of Electric Machine and appliance)

• (1) The employer shall, when using the electric machine and appliance listed in the left column of the following table, check the matters listed in the right column of the same table corresponding to the type of the said electric machine and appliance, and immediately repair or replace it when having found any abnormalities.

  Types of electric machine and appliance	Checking Matters
  A holder for welding rod, etc., set forth in Article 331	Damage on the insulated protected portion and connected portion of the cable for holders
  Automatic voltage reducing device for A.C. arc welding machine set forth in Article 332	Condition of operation
  Earth-leakage circuit breaker for preventing an electric shock set forth in paragraph (1) of Article 333
  Motor-driven appliance set forth in Article 333 that are grounded by the method set forth in paragraph (2) of the said Article	Abnormalities, such as cutoff grounding conductor and uplift or lift of grounding pole
  Movable electric cables and their connecting tools set forth in Article 337	Damage on the cover or armor
  Voltage detector set forth in item (iii) of paragraph (1) of Article 339	Voltage detecting capability
  Appliance for short circuit to ground set forth in item (iii) of paragraph (1) of Article 339	Damage on fittings and grounding lead wires
  Personal insulating protective equipment set forth in Articles 341 to 343	Damage such as cracks, splits and breakages , and drying conditions
  Insulating device set forth in Articles 341 and 342
  Live line work equipment set forth in Articles 341 and 343 to 345
  Live line work instruments set forth in Articles 341, 343 and 344
  Personal insulating protective equipment and live line work instruments set forth in Articles 346 and 347 and insulating device set forth in Article 347
  Insulating device set forth in item (iii) of Article 349 and item (vi) of paragraph (1) of Article 570

Article 353 (Checkup, etc., of an Enclosure, etc., of Electric Machine and Appliance)

• (1) The employer shall check damage of the enclosure and insulating cover set forth in Article 329 once or more a month, and immediately repairs it when having found any abnormalities.

Section 6 Miscellaneous Provisions

Article 354 (Exemptions)

• (1) The provisions of this Chapter shall not apply to electric machine and appliance, wiring or movable electric cables with voltage to ground of 50 V or less.

• Part II Safety Standards
• << INDEX
• Chapter I
• Chapter I-2
• Chapter II
• Chapter III
• Chapter IV
• Chapter V
• Chapter VI
• Chapter VII
• Chapter VIII
• Chapter VIII-2
• Chapter VIII-3
• Chapter VIII-4
• Chapter VIII-5
• Chapter VIII-6
• Chapter IX
• Chapter X
• Chapter XI
• Chapter XII

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