{"id":1472,"date":"2023-10-15T06:35:34","date_gmt":"2023-10-15T06:35:34","guid":{"rendered":"https:\/\/www.nfees.org\/blog\/?p=1472"},"modified":"2025-03-29T13:30:47","modified_gmt":"2025-03-29T13:30:47","slug":"lifts","status":"publish","type":"post","link":"https:\/\/www.nfees.org\/blog\/lifts\/","title":{"rendered":"Electrical Safety in Lifts, and the Challenges"},"content":{"rendered":"
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Lifts for Transport of Persons and Goods<\/strong><\/span><\/h5>\n<\/div>\n

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IS17900: 2022<\/strong><\/span><\/h5>\n

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Electrical Safety in Lifts, and the challenges<\/strong><\/span><\/h5>\n<\/div>\n
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1. Introduction<\/strong><\/span><\/p>\n<\/div>\n

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This article explains the violations and nonstandard arrangements from the established Electrical safety provisions of the CEA Regulations, Codes, and Standards, jeopardising the safety of the public from electrical hazards, especially, in lift installations.<\/span><\/p>\n<\/div>\n

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BIS published the new IS standard IS17900: Lifts for Transport of Persons and Goods. The new standards part 1 and 2 together supersedes IS 14665 (Part 1), IS 14665 (Part 2\/Sec 1), IS 14665 (Part 3\/Sec 1), IS 14665 (Part 4\/Sec 1 to 9), IS 14671 and IS 15785. <\/span><\/p>\n<\/div>\n

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IS17900 is based on ISO 8100, Lifts for the transport of persons and goods. Part 1 of the standard is on Safety rules for the construction and installation of passenger and goods passenger lifts. <\/span><\/p>\n<\/div>\n

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IS17900-1 requires compliance with IS732 for protection against electric shock and thermal effects (ref clause 5.10.1.1.6, 5.10.1.2.1, 5.10.1.3, 5.10.9 & 6.3.2<\/em>) <\/span><\/p>\n<\/div>\n

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In general, the new IS17900 is going to have an impact in the construction industry.<\/span><\/p>\n<\/div>\n

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Any violations could seriously affect the safety of passengers, reliability of the electrical and electronic devices in the lift as well as reliability of the other parts of the electrical installation in the building premises. The article also explains the reasons why noncompliance could endanger the safety of property and persons.<\/span><\/p>\n<\/div>\n

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Note: Though several Improvements are included in IS17900 (part 1 and 2), electrical safety related points are mainly addressed in this article.<\/span><\/p>\n<\/div>\n

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2. Mistakes in old Standards<\/strong><\/span><\/p>\n<\/div>\n

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There were few mistakes and wrong requirements in the earlier standards of lifts (IS14655 series which is superseded now), which created large scale confusion in the construction industry in India and resulted in the violation of basic electrical safety measures. The confusions is due to the following clauses in the earlier standards.<\/span><\/p>\n<\/div>\n

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\u200bIS14665 Amendment no 1 to (part2\/sec1):2000 cl. 8.4.4.7: \u201cthere shall be separate earth pit for lift\u201d. <\/span><\/p>\n

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IS 14665 (Part 5):1999 Table 4 Inspection of Lift from Machine Room. SL no 15 \u201cThe earthing arrangement shall be proper, and the electrical contractor\/owner shall ensure that earth resistance shall not exceed one ohm as per Indian Electricity Rules\u201d.<\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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Due to the misleading clauses in IS14665, each lift is connected to two separate earth pits. The state government departments, while implementing Lift rules insist on the compliance with IS14665. Over a period, these mistakes became an industry practice, resulting complete violation of electrical safety requirements across India, in almost all installations. Users were unnecessarily carrying out research to reduce the earth electrode resistance to less than one ohm and wrongly believe that every failure in lift installation is due to higher earth electrode resistance.<\/span><\/p>\n<\/div>\n

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\u200bNote: <\/span><\/p>\n

This article does not consider the clauses 6.2.2 and 6.2.4 in NBC 2016.<\/span><\/p>\n

Clause 6.2.2 is not specific about fault protection or additional protection.<\/span><\/p>\n

Clause 6.2.4 is misinterpreted from IS3043 (even though it refer to IS3043). <\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n

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\u200bPART 8 BUILDING SERVICES: Section 5 Installation of Lifts, Escalators and Moving Walks:<\/span><\/p>\n

5A Lifts<\/span><\/p>\n

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6.2.2 Residual Current Device: Residual current device (RCD), if provided, right type and sensitivity shall be selected. The RCD shall, <\/span><\/p>\n

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    have 10 times the maximum leakage current (300 mA maximum) as tripping current and be suitable for frequency converters with a 3-phase supply.<\/span><\/p>\n<\/li>\n

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    be sensitive for sinusoidal currents up to l000 Hz, insensitive for currents more than 1000 Hz.<\/span><\/p>\n<\/li>\n<\/ol>\n

    NOTE \u2014 This kind of RCDs are generally classified as \u2018Type B\u2019.<\/span><\/p>\n

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    Three-phase power supply for the lift should never be protected with a 30mA residual current device (RCD). The 30 mA RCD trips easily when the lift starts to drive and prevents the lift to run. If the construction-time power supply is for some reason protected with a 30mA residual current device (RCD), suitably sized isolation transformer needs to be provided by the electrical contractor<\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n

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\u200bPART 8 BUILDING SERVICES: Section 5 Installation of Lifts, Escalators and Moving Walks:<\/span><\/p>\n

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6.2.4 Earthing<\/span><\/p>\n

There shall be separate exclusive earth pit for the lift or a group of lifts or the same shall be connected to equipotential bonding system. There shall be two separate and distinct earth conductors provided from the earth pit to the machine room as per good practice [IS3043]. The cross-sectional area of copper earthing conductor shall be not smaller than half that of the largest current-carrying conductor subject to an upper limit of 65 mm2. <\/span><\/p>\n

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In case of buildings having earthing through earth mats or earth grids, it is permissible to earth the lift equipment with separate conductors from these earth mats\/grids. Separate earth pits shall not be a requirement in this case.<\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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3. Measures prescribed in IS3043: Code of Practice for Earthing<\/strong><\/span><\/p>\n<\/div>\n

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The following clause from IS3043: 2018 helps to understand the subject in a simple way.<\/span><\/p>\n<\/div>\n

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Clause 23.1 Basic Purpose of Earth Fault Protection<\/span><\/p>\n

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The earth fault loop impedance has to be low enough to allow adequate earth fault current to flow to cause an overcurrent protective device (for example, a fuse or circuit breaker) in the faulty circuit to operate in a sufficiently short time.<\/span><\/p>\n

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Where it is not possible to achieve a low enough earth fault loop impedance, disconnection may be initiated by fitting a residual current device (RCD) of 30 mA rating as specified in IS 732.<\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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Hence using RCD\u2019s with residual operating current > 30 mA, is mandatory in case of a \u201cfailure of fault protection by OCPD\u201d as an earth fault protective measure. <\/span><\/p>\n<\/div>\n

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4. Measures prescribed in CEA regulations 2023<\/strong><\/span><\/p>\n<\/div>\n

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Further the following mandatory requirements of the National Electrical Safety Regulation of Central Electricity Authority (Measures Relating to Safety and Electric Supply) Regulations 2023 must be fulfilled,<\/span><\/p>\n<\/div>\n

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\u200bRegulation 43. Connection with earth <\/strong><\/span><\/p>\n

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(ix) All earthing systems shall, – (b) have earth fault loop impedance sufficiently low to permit adequate fault current for the operation of protective device within the time stipulated in the relevant standards.<\/span><\/p>\n

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(xi) earth fault loop impedance shall be tested to ensure the automatic operation of the protective device and a record of every earth test made and the result thereof shall be kept by the supplier for a period of not less than two years after the day of testing and shall be available to the Electrical Inspector when required.<\/span><\/p>\n

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(xii) earth fault loop impedance of each circuit shall be limited to a value determined by the type and current rating of the protective device used such that, on the occurrence of an earth fault, disconnection of the supply shall occur before the prospective touch voltage reaches a harmful value.<\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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5. The new and modern requirements prescribed for lifts and escalators.<\/strong><\/span><\/p>\n<\/div>\n

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The following provisions are already prescribed in the standards but mostly misunderstood:<\/span><\/p>\n<\/div>\n

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    Clause 5.10.9 of IS 17900 (Part 1): 2022 recommends making protective earthing as per IS732, clause 4.2.11.3.1.1.<\/span><\/p>\n<\/li>\n

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    It should also be observed that the circuit protective device should clear the overcurrent in a disconnection time of the of less than 0.4 second as prescribed in Table 1 of IS732. <\/span><\/p>\n<\/li>\n

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    Selection of wiring system and method of Installation as per cl 5.3, 5.4, 5.5.1 to 3 and Table-2 of IS 732.<\/span><\/p>\n<\/li>\n

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    Coordination between circuit protection device, design load current, and current rating of cable (after derating as per Cl.4.6.2.3 under Section 12, Part 1 of NEC, and Cl. 4.4.5.5.2 and Table 3 of IS 732) as per Cl.4.5.1 under Section 12, Part 1 of NEC. <\/span><\/p>\n<\/li>\n

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    Compliance of non-trip conditions of the circuit protective devices for inrush current during starting as per Table 7 of IS\/IEC 60898. <\/span><\/p>\n<\/li>\n<\/ol>\n<\/div>\n

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    \u200bIS 732:2019, Clause 4.2.11.3.1.1 Protective earthing<\/span><\/p>\n

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    Exposed conductive parts shall be connected to a protective conductor under the specific conditions for each type of system earthing as specified in 4.2.11.4 to 4.2.11.6.<\/span><\/p>\n

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    Simultaneously accessible exposed conductive parts shall be connected to the same earthing system individually, in groups or collectively. Conductors for protective earthing shall comply with 5.4 and IS 3043.<\/span><\/p>\n

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    Each circuit shall have available a protective conductor connected to the relevant earthing terminal.<\/span><\/p>\n

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    Note: 4.2.11.4, 4.2.11.5 and 4.2.11.6 explains TN system, TT system and IT system respectively.<\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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    The above non-compliance makes the installation unsafe due to improper operation or failure of the protective devices to trip during a fault.<\/span><\/p>\n<\/div>\n

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    \u200bNote: Readers are also requested to understand the concept of Basic protection, Fault protection and Additional protection explained in IS732 to understand the subject.<\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n

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    \u200bIS 17900 (Part 1): 2022 clause 5.10.1.2 Protection against electric shock,<\/span><\/p>\n

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    5.10.1.2.1 General<\/span><\/p>\n

    The protective measures shall comply with the provisions defined by IS 732.<\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n

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    \u200bIS 17900 (Part 1): 2022 clause 5.10.1.2.3 Additional protection,<\/span><\/p>\n

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    Additional protection by means of a residual current protective device (RCD) with a rated residual operating current not exceeding 30 mA shall be provided for: <\/span><\/p>\n

    a) socket outlets depending on the circuit(s) according to 5.10.1.1.1 b) and 5.10.1.1.1 c); <\/span><\/p>\n

    b) control circuits for landing controls and indicators and the safety chain with voltage higher than 50 V AC; <\/span><\/p>\n

    circuits on the lift car with voltage higher than 50 V AC.<\/span><\/p>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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    6. Existing Method of Installation:<\/strong><\/span><\/p>\n<\/div>\n

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    The currently followed method of connecting exposed conductive parts of lift (say lift earthing) to separate and independent earth electrodes (sometimes interconnected under soil) is a mistake and a violation of basic electrical safety requirements. This wrong method could lead to the deterioration of electrical system, serious electrical accidents and failure of electrical and electronic system and could ignite a fire.<\/span><\/p>\n<\/div>\n

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    \u200bExample of a safety issue: <\/span><\/p>\n

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    As a result of connecting exposed conductive parts of lift to a separate earth electrode, that part of the electrical installation becomes TT. Fault protection by OCPD & Protective equipotential bonding and automatic disconnection of supply is compromised. Hence 30 mA RCD at the lift panel becomes mandatory as recommended in IS732.<\/span><\/p>\n

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    Note: <\/span><\/p>\n