[Class 1] Laws and High-Voltage Diagrams

Article 39(1) of the Electricity Business Act puts the duty to maintain the facility in line with the technical standards on the person who installs it. An electrician's duty is to do the work so that it meets the technical standards (Electricians Act (電気工事士法), Article 5); it is not a duty to maintain the facility. The power line operator investigates general electrical facilities (Article 57). An electrical contractor takes on the work but is not the party that maintains the finished facility.

Under Article 40 of the Electricity Business Act, when the competent minister finds that a business-use facility does not meet the technical standards, the minister may order the installer to repair, modify or move it or to stop using it for a time, or may restrict its use. Ordering an electrician to return a licence is done by the prefectural governor under the Electricians Act, not under this article. Article 40 does not provide for ordering a contractor to repair for free or ordering the power line operator to remove the facility.

Under Article 42(1) of the Electricity Business Act, the installer of a business-use facility (other than a small business-use facility) makes safety rules for each organisation that must secure safety as a unit, and files them with the competent minister before use starts. There is no one-year grace period after use starts, and they are not filed with the governor. The installer makes the rules, not the chief engineer or the contractor.

Under Article 42(2) of the Electricity Business Act, when the safety rules are changed, the installer must notify the competent minister of the changes without delay. It is not a system of approval before the change. Nothing says the chief engineer's agreement removes the need to file. Waiting until the next periodic inspection would not be "without delay".

Under Article 43(3) of the Electricity Business Act, when a licence holder is appointed chief engineer, the installer notifies the competent minister without delay (the same applies when the chief engineer is dismissed). Permission from the minister is needed only when a person without a licence is appointed (Article 43(2)). The notice does not go to the governor, and there is no one-year deadline. Posting a name does not replace the notice.

Under Article 43(2) of the Electricity Business Act, the installer of a private-use facility (other than a small business-use facility) may appoint a person without a chief engineer licence only with the competent minister's permission. A first-class electrician licence is not a chief engineer licence, so it does not allow appointment without permission. Years of experience alone do not remove the need for permission. Notice after appointment is the procedure for appointing a licence holder (Article 43(3)); appointing a person without a licence needs permission in advance.

Under Article 43(5) of the Electricity Business Act, people engaged in the construction, maintenance or operation of business-use facilities must follow the instructions the chief engineer gives for safety. Holding an electrician licence does not change this. The article says "people engaged" and is not limited to the installer's employees, so outside workers are included. There is no rule allowing workers to ignore an instruction because it is stricter than the technical standards.

Under Article 56 of the Enforcement Regulations of the Electricity Business Act, a third-class chief electrical engineer may supervise business-use facilities below 50,000 V, except power plants and storage facilities of 5,000 kW or more. Demand facilities receiving at 6,600 V qualify. The 66,000 V demand facilities and the 77,000 V substation are 50,000 V or more, so they need a second-class (below 170,000 V) or higher licence. The 22,000 V solar plant is below 50,000 V, but its output is 5,000 kW or more, so it is excluded from the third-class scope.

Article 52(2) of the Enforcement Regulations lists demand facilities receiving power at 7,000 V or below among the facilities that need no chief electrical engineer when a contract to outsource safety management work is made and approved. Demand facilities receiving at 22,000 V or 77,000 V do not meet this condition. The condition depends on the receiving voltage; there is no rule that any facility under 500 kW may outsource regardless of voltage.

Under Article 52(4) of the Enforcement Regulations of the Electricity Business Act, the installer must not, in principle, have one chief engineer serve for two or more sites or facilities. It is allowed when approval is given because safety will not be compromised. Being in the same company or filing a notice is not enough, and the licence class does not remove the limit. Because approval allows an exception, "never allowed" is also wrong.

Article 3 of the Regulations makes deaths and hospital admissions caused by electric shock reportable accidents. A quick report (by phone or similar) is made as soon as possible within 24 hours of learning of the accident, and a written report is submitted within 30 days of the day of learning of it. Reports go to the head of the regional Industrial Safety and Inspection Department (産業保安監督部長) for the site. There is no condition on the length of the hospital stay, and it is not limited to deaths. A report to the governor or a 3-month deadline is not provided for.

Article 3 of the Regulations makes reportable an accident in which damage to a private-use facility of 3,000 V or more, or wrong operation or failure to operate it, causes a supply disruption for a general transmission and distribution utility or similar. An earth fault in the HV service cable that trips the utility line and cuts power to the neighbourhood is such an accident. A tripped earth-leakage breaker cuts power only inside the site at low voltage, not the utility's supply. When lightning trips the line, the factory's equipment is not the cause. A motor burning out with no power cut causes no supply disruption.

Article 1-2 of the Enforcement Regulations of the Electricians Act excludes power plants, storage facilities, substations, demand facilities of 500 kW or more, transmission lines and safety communication systems from private-use facilities under the Act. The HV receiving equipment of a 450 kW building is not excluded, so it is within the first-class scope. A solar power plant is a power plant, 800 kW demand facilities are 500 kW or more, and a safety communication system is excluded, so none of these is covered by the licences under the Act.

Article 2-2 of the Enforcement Regulations of the Electricians Act defines neon work as work on the distribution board, main switch (excluding the part connecting the supply-side wires), time switch, switches, neon transformer, neon tubes and their accessories installed for neon. The connection of the supply-side wires to the main switch is excluded, so it is not special work and a first-class electrician may do it. Work on the neon transformer, the time switch, and the tubes and accessories is neon work and needs a special electrical work qualification (特種電気工事資格者) for neon work.

Article 2-2 of the Enforcement Regulations of the Electricians Act defines emergency standby generator work as work on the prime mover, generator, switchboard (excluding the part connecting wires to other demand equipment) and their accessories installed as an emergency standby unit. The connection between the switchboard and wires to other demand equipment is excluded, so a first-class electrician may do it. Work on the prime mover, the generator and their accessories is special electrical work and needs a special qualification for emergency standby generators.

Under Article 4-2(1) of the Electricians Act, both certificates are issued by the Minister of Economy, Trade and Industry. Under Article 14 of the Order for Enforcement, the power to issue them is exercised by the head of the Industrial Safety and Inspection Department for the applicant's address. Prefectural governors issue electrician licences, not these certificates. The Examination Center runs exams and does not issue certificates. Special work certificates are issued separately for each kind of special work (Article 4-2(2)).

Under Article 4-3 of the Electricians Act, a first-class electrician must, unless there is an unavoidable reason, take a course on the safety of private-use electrical facilities run by a body designated by the Minister within 5 years of the licence being issued. The period is not 3 years. The duty applies only to first-class electricians. The article says the same applies after each course, so it is not a one-time duty; the course is taken again within every 5 years.

Under Article 17-2 of the Electrical Contractors Act, a person who will do only private-use electrical work gives notice at least 10 days before the day the business is to start. When all offices are in one prefecture, the notice goes to that prefecture's governor. Registration is needed for businesses that include general electrical work (Article 3). Notice to the Minister applies when there are offices in two or more prefectures. Notice after starting would not meet the 10-days-before deadline.

Under Article 21(4) of the Electrical Contractors Act, a contractor may assign certified electrical workers (認定電気工事従事者) to simple electrical work, meaning work on private-use facilities used at 600 V or below, excluding power lines. In principle, only first-class electricians may be assigned to private-use work (Article 21(1)). Three years of experience for a second-class electrician is a requirement for chief electricians, not a qualification for private-use work. Neon work and emergency standby generator work are special work, for which only holders of the matching special qualification may be assigned (Article 21(3)).

The duty to appoint a chief electrician (Article 19 of the Electrical Contractors Act) applies to offices of registered contractors that do general electrical work. A notified contractor doing only private-use work has no such duty. On the other hand, the duties to keep instruments (Article 24) and records (Article 26) apply to "electrical contractors", which include both registered and notified contractors (Article 2).

Article 11(1) of the Enforcement Regulations of the Electrical Contractors Act lists the instruments for offices doing private-use work: insulation resistance tester, earth resistance tester, a multimeter that measures resistance and AC voltage, low-voltage detector, high-voltage detector, relay testing equipment and dielectric strength testing equipment. For the relay testing equipment and the dielectric strength testing equipment only, it includes cases where "arrangements are in place to use them when needed". The high-voltage detector, insulation resistance tester and earth resistance tester do not get this treatment.

(1) is a pole-mounted load-break switch with a ground relay (GR付PAS), the first section switch on the customer side. When the GR detects an earth fault on the premises, it opens automatically and keeps the fault from spreading to the utility's distribution line (a supply disruption accident). Diverting abnormal voltage to earth is the job of the surge arrester (4), transforming for metering is the VCT (5), and improving the power factor is the capacitor (11).

(3) is a disconnector (断路器). It is used to open and isolate a circuit for inspection and similar work, and it cannot switch current. So it is operated when no load current is flowing. It cannot interrupt short-circuit current, and opening it under load would draw an arc and be dangerous. The device opened automatically by the overcurrent relay (OCR) is the vacuum circuit breaker (VCB) (6).

Under Article 37(3) of the Interpretation, surge arresters on high-voltage and extra-high-voltage circuits get Class A earthing. Class B is for the low-voltage neutral of a transformer linking high and low voltage (Article 24), Class C is for metal enclosures of low-voltage equipment over 300 V (Article 29), and Class D is for the secondary circuit of high-voltage instrument transformers and enclosures of low-voltage equipment of 300 V or less (Articles 28 and 29).

Article 37(1)(iii) of the Interpretation requires a surge arrester at (or near) the service entrance of a customer supplied from a high-voltage overhead line with a receiving capacity of 500 kW or more. 50 kW, 300 kW and 2,000 kW are not the threshold in this article. Article 49 of the Ministerial Ordinance on technical standards also requires surge arresters or other suitable measures at service entrances where lightning voltage could damage the equipment.

A VCT (計器用変圧変流器) combines a voltage transformer (VT) and a current transformer (CT) in one unit as an instrument transformer for power trading. It sends voltage and current to the watt-hour meter (Wh) to meter energy for billing. A zero-phase current transformer (ZCT) detects the zero-phase current that flows in an earth fault and is used with a ground relay. A voltage transformer converts only voltage ((7) in the figure), and a current transformer only current ((8)).

The CT (8) converts the current to a small current and sends it to the OCR (overcurrent relay). When the OCR detects overcurrent, it trips the VCB (vacuum circuit breaker) (6) to interrupt short-circuit current and the like. The dashed lines in the figure show these signals. The disconnector (3) cannot switch current. The PAS (1) opens on a signal from the GR (ground relay) and is not connected to the OCR. The LBS with PF (9) interrupts a short circuit by its current-limiting fuses blowing, not by an OCR signal.

Under Article 28(1) of the Interpretation, the secondary circuit of a high-voltage instrument transformer gets Class D earthing (for extra-high-voltage instrument transformers it is Class A). Class A is for surge arresters and metal enclosures of high-voltage equipment, Class B for the low-voltage neutral of a transformer linking high and low voltage, and Class C for metal enclosures of low-voltage equipment over 300 V.

Article 34(1) of the Interpretation requires an overcurrent breaker on a high-voltage or extra-high-voltage circuit to be able, if it operates on a short circuit, to interrupt the short-circuit current passing that point, and to have a device that shows its open or closed state when it operates (not needed if the state is easy to see). Blowing within 2 minutes at twice the rated current is the requirement for high-voltage non-enclosed fuses in Article 34(3). An alarm to a staffed station is a rule allowing an earth-fault breaker to be omitted (Article 36(5)). Diverting abnormal voltage to earth is the job of a surge arrester.

(10) is a series reactor (直列リアクトル). The Japan Electrical Manufacturers' Association (日本電機工業会) explains that a series reactor improves system voltage distortion caused by harmonics and suppresses the capacitor's inrush current, and recommends it also to avoid capacitor damage from harmonics. Improving the power factor is the job of the power capacitor (11). Interrupting short-circuit current to disconnect the capacitor is done by the current-limiting fuses of the LBS with PF (9). Transforming for billing is the job of the VCT (5).

(11) is a high-voltage power-factor-correction capacitor (高圧進相コンデンサ). It supplies leading current to lagging loads such as motors, improving the power factor and, as the Japan Electrical Manufacturers' Association explains, reducing wasted power. Reducing harmonic voltage distortion is the job of the series reactor (10). Stepping 6,600 V down to 210 V is done by the transformers (12)(13). Detecting an earth fault and opening is done by the PAS with GR (1).

A high-voltage load-break switch (LBS) is a disconnector with an arc chamber added so that it can switch load current. The fuse-equipped type can interrupt short-circuit current by blowing its current-limiting fuses. The switch contacts alone do not interrupt short-circuit current. A device that may be operated only with no current flowing is a disconnector, and fuses are not used to switch load current. Opening automatically on an earth fault is done by the PAS with GR (1).

Under Article 24 of the Interpretation, a transformer linking a high-voltage circuit and a low-voltage circuit gets Class B earthing at the low-voltage neutral. This protects against the danger of the low-voltage side rising in voltage to earth if the high and low windings come into contact. Class A is for high-voltage equipment such as surge arresters and transformer metal enclosures, Class C for enclosures of low-voltage equipment over 300 V, and Class D for the secondary circuits of high-voltage instrument transformers.

Article 21(iv) of the Interpretation allows high-voltage equipment to be put in a concrete box or a metal box with Class D earthing, with no live parts exposed. A metal box needs Class D earthing, so an unearthed box does not qualify. Putting it in a wooden box is not a listed method. Installing it high up (item iii) requires a height of 4.5 m or more above the ground (4 m outside urban areas) and cables or similar for the attached high-voltage wires.

Article 23 of the Interpretation says that high-voltage and extra-high-voltage switches, breakers, surge arresters and similar devices that produce an arc when operating must either have the arcing part enclosed in fire-resistant material or be kept at least the distance in Table 23-1 from combustible materials such as wooden walls and ceilings. For high voltage it is 1 m. 2 m is the value for extra-high voltage (1 m if the voltage is 35,000 V or less and the arc direction and length are limited), and 0.5 m and 3 m are not in the table.