Reinforcing NEC 110.3(B) and NEC 110.10 to require the elevator controller marked SCCR to be equal to or greater than the calculated and Selective coordination is also required for multiple elevators per NEC 620.62. Selective coordination is defined by the NEC as: Localization of an overcurrent condition to restrict outages to the circuit or equipment affected, accomplished by the selection and installation of overcurrent protective devices and their ratings or settings for the full range of available overcurrents, from overload to the maximum available fault current, and for the full range of overcurrent protective device opening times associated with those overcurrents.. One way to achieve this is by paralleling wires, i.e., connecting the runs at both ends so they are physically like two wires but electrically one. While the definitions are straightforward, their deployment in real-life building projects involves enormous legal and moral implications, given the fact that we are carrying large numbers of people hundreds of feet above the earths surface on a daily basis. Marking the available short-circuit (fault) current on the controller by the equipment installer. This position paper is written to provide guidance to members whose employees are engaged in elevator-industry work that might expose them to arc-flash hazards, and to assist members in complying with applicable OSHA and National Fire Protection Association (NFPA) standards. He has focused on writing since 2006, having written for such magazines as ELEVATOR WORLD, Electrical Construction and Maintenance, Cabling Business, Electrical Business, Nuts and Volts, PV Magazine, Electrical Connection, Solar Connection, Solar Industry Magazine, Fine Homebuilding Magazine and Engineering News. The two primary hazards are fire and electric shock or arc flash, although there are others. The many codes and guidelines that regulate the electrical design of an elevator can seem overwhelming, and dealing with the electrical inspector, elevator inspector, and Fire Marshal can be even more intimidating. If we fast forward more than 36 centuries, we see some important new developments in elevator technology. These are the principle NEC 2011 Article 620 mandates. Based on the analysis, the arc-flash boundaries at the elevator/escalator controllers ranged from 3-16 in. ASME A17.1, Section 2.2.5, National Electrical Code, Rule 620-85 4. By subscribing, you agree to our User Agreement and Privacy Policy & Cookie Statement. Many people use portable generators until power is restored. Motor controllers are permitted outside the spaces specified above. Click to reveal The various items to consider and check when designing for elevator installations have many potential pitfalls. Any other utilization equipment associated with the elevator 2m9 `K]f*F gaR
Be sure to provide a horn/strobe alarm in large equipment rooms because they can be noisy, isolated places. Additional branch circuits are to supply other utilization equipment not covered above. Get more of Elevator World. The NEC rule specifies that the minimum size for paralleled conductors is 1/0 AWG, which is much too big for an elevator traveling cable. You need to Subscribe to continuing reading. Your elevator supplier will take care of all the wiring and related code requirements for the elevator cab and the various controls. It is further specified the machine-room lighting switch be located at the point of entry. A clean and dry elevator pit and machine/control room provided (ASME A17.1 Rule 2.1.2) Machine/control room meets manufacturer's requirement of preserving ambient temperature control and humidity (ASME A17.1 Rule 2.7.9) Elevator floor covering installed with appropriate smoke and flame spread (ASME A17.1 Rule 2.14.2) For all of this to come together in the real world, there had to be some assurance that these new technologies could be used safely on a wide scale. Acceptable types of wire for this application are given in Table 400.4, which occurs in an earlier chapter and lists various types of elevator cable for lighting and control in both unclassified and hazardous locations. The thinking behind this requirement is that the injured worker could have severe hand burns and be unable to operate a conventional doorknob. When the elevator car is at the top landing, it is the length of cable as measured from the point of suspension on the car to the bottom of the loop. Accordingly, for this application, the minimum size is reduced to 20 AWG for lighting circuits. . A single means for disconnecting all ungrounded main power-supply conductors is required and must be designed so no pole can be operated independently. Luminaires must be lensed or equipped with wire guards to protect the lamps. This switch will ensure that the elevator won't descend into the elevator pit and allow maintenance people to work safely in the area beneath the cab. The cover shall be secured and level with the pit floor. Flexible cords and cables (same conditions as within hoistways). Hoistway door interlock wiring from the riser must be flame retardant and have insulation suitable for a temperature not less than 200C (392F), much higher than that required for most raceway or cable applications. The action you just performed triggered the security solution. If the equipment must remain energized to perform work, effective insulation and safe electrical working practices should be observed. [emailprotected] from the exposed components, and the incident energy calculated at 18 in. Society of Mechanical Engineers. Many undertake trips in these devices two or more times daily in full confidence that they will survive an uneventful experience with a minute chance of disaster or even inconvenience. The electrical system designer needs to communicate this information to the person responsible for specifying the elevator controller, which is most often the architect. You are a subscriber that needs to Sign In. Fuses: Verify that the correct size, type and capacity are installed. Finally, in 1897, the first National Electrical Code (NEC) appeared. This may include wiring for signals, communication with the car, lighting, heating, air-conditioning and ventilation of the car or hoistway for fire-detecting systems and pit sump pumps. For elevators that regenerate power back into a power source unable to absorb the regenerative power under overhauling elevator load conditions, a means to absorb this power is to be provided. For circuit breakers, time-current curves must be consulted as well as the circuit breaker manufacturers selective coordination tables. Section 620.37 re-emphasizes that only wiring used in connection with the elevator is permitted within the hoistway, machine room, control room/machinery space or control space. GET YOUR CEUS TODAY, 1998-2021. Thus, the need for door interlock functionality is recognized. Please check your entries and try again. Many NEC articles address voltage limitations, and Article 620 is no exception. Fluid pressure in the cylinder raises and lowers the elevator cab. Overcurrent devices protecting these branch circuits are to be located in the machine room or similar location. +91 8025357028, 2022 Elevator World, LLC. The traveling cable, of necessity, is exempted. This room is to be secured against unauthorized access (kept locked). The light switch for the equipment room must be adjacent to the entrance door on the latch side. In an elevator machine room, where space may be limited in the first place, the working-space mandate must be factored in very early in the design process lest an unthinkable amount of rework be necessary. The elevator rails, like the ground system of the entire building electrical structure, are to be bonded to the lightning-system ground electrode so these all remain at the same potential even during a lightning event, ensuring side flash does not occur. Hard-service cords are permitted only as flexible connections for the top-of-car operating device or the car-top work light. A single dedicated receptacle supplying a permanently installed sump pump does not have to be a GFCI type. A few years later, in 1880, Werner von Siemens built the first electric elevator, setting the stage for a new industry that would change the world by making the practical use of tall buildings possible. The proposals resulted in adding new requirements in the 2017 NEC for: Marking the elevator controller short-circuit current rating (SCCR) by the elevator control-ler manufacturer. Special conditions: Troubleshooting in wet, hot or cold conditions calls for extra caution. It employs specialists in Mobile, Alabama, and has technical and news correspondents around the world. The disconnecting means is to be located adjacent to or an integral part of the motor controller. In addition, the shunt-trip voltage must also be monitored by the Fire Alarm System. The Code provides guidance through regulations to establish requirements. On existing or listed equipment, conductors are permitted to be grouped together and taped or corded without being installed in a raceway. Sign up for our free e-newsletter. NEC has a further note that the term wheelchair lift has been changed to platform lift.. First, you'll need to install lighting in the elevator equipment room (Photo 1) and shaft pit (Photo 2). If power is not being supplied to the elevator controller (e.g., open mainline fuses, etc. Instruments: Use category III multimeters and be familiar with their use and limitations. Elevator power disconnect (with utility feed marking) located in the machine room or other permitted location. 974 0 obj
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In driving through commercialized suburban areas, you frequently see paralleled conductors for large retail grocers (where there is a heavy refrigeration load). In some cases, it may require a means to test the shunt trip operation or have one contact operate the shunt trip of more than one elevator. This is especially true in an elevator shaft where measures have to be taken to ensure that a hazardous situation is not created. Cloudflare Ray ID: 7a2fbe9ebd7e2fe8 Similar provisions are attached to elevator-car heating and air-conditioning disconnecting means, and to other utilization equipment. The fan should be on a dedicated circuit. Where voltages exceed 600, a sign reading DANGER HIGH VOLTAGE is required. Many professionals believe the NEC is applicable only for voltages over a certain level, but that is not the case. Similarly, the integrity of the traveling cable is emphasized. Other codes and standards interact with the NEC, and it is necessary to see how they all work together in order to create safe and compliant elevator designs/installations. They are to be part of listed equipment, a driving machine or a driving-machine brake. Mobile, AL 36606 USA Even non-composite fiber-optic cable, which does not carry electrical energy, is subject to the code. Described below are several work practices that may be used to reduce arc-flash hazards when working on energized equipment: David Herres holds a New Hampshire Master Electricians license and has worked as an electrician in the northern part of that state for many years. It is mandatory, as in the car, that these items have a separate, dedicated branch circuit, and the required lighting is not to be supplied through a GFCI. When you consider that an elevator is an enclosed room with one or more doors that people voluntarily enter so they may travel hundreds of feet up or down, several observations are in order. In order to comply, the electrical system designer must determine the maximum available fault current at the elevator disconnecting means and assure the elevator disconnecting means overcurrent protective device will clear any overcurrent condition, up to the maximum available fault current, before any upstream overcurrent devices will operate. There are options available to achieve this depending upon the customers needs. If elevators are supplied by the emergency, legally required standby or critical operation power systems, then selective coordination is required per the 2017 NEC in 700.32, 701.27 or 708.54. The disconnecting means is to be an externally enclosed, operable, fused motor circuit switch or circuit breaker capable of being locked in the open position. It is of great importance that power to the various elevator functions can be quickly and reliably removed from the loads in case of emergency or for maintenance and troubleshooting. Bonding of elevator rails to a lightning-protection system grounding conductor is permitted, but the conductor itself is not to be located in the hoistway. Both electric and nonelectric elevators are to comply with Article 250, the code article that covers grounding and bonding in general. No provision is to be made to automatically restore power. Part VII, Overcurrent Protection, divides this topic into four categories for elevators and similar equipment, depending upon the nature of the specific equipment: For operating devices and control and signaling circuits, protection against overcurrent is in accordance with the requirements of Sections 725.43 and 725.45. ASME A17.1 . For current-limiting fuses, the information to achieve selective coordination has been available for many years in fuse amp ratio tabular form. NEC Article 620 Part IV, Installation of Conductors, contains key mandates for elevator wiring. Article 620 follows this pattern by opening, in Section I, General, with a statement of scope and definitions applicable to the topic under consideration. (e) Pit Maintenance. 6 feet, and shall meet the requirements of NEC 70 620.21(A)(1)(d). It is further stated that the disconnecting means are not to disconnect the branch circuits required in sections 620.22, 620.23 and 620.24. Within cars, these additional wiring methods are permitted: The following additional wiring methods are permitted on the car assembly in lengths not exceeding 6 ft.: Within machine rooms, these additional wiring methods are permitted: The following wiring methods are permitted on the counterweight assembly in lengths not to exceed 6 ft.: Having looked at NEC 2011 mandates for elevator and related equipment installations, we will cover wiring methods, overcurrent protection, grounding and other related NEC provisions in part two of this series , running in the April 2012 issue of ELEVATOR WORLD. The code notes that elevator rails or other hoistway equipment are not to be used as the grounding conductor for lightning-protection systems. This may be countered by providing good machine-room ventilation. IAEI News Magazine. [emailprotected] Overload protection for motors is to conform with Article 430, Part III, the general code area that covers motor and branch-circuit overload protection for all motors. Power for the elevator controller must first enter a lockable safety disconnect device, located adjacent to the door of the equipment room. [emailprotected] It is further stressed that no provision is to be made to open or close the disconnecting means from any other part of the premises. You are seeing this message for one of three reasons: You have reached your limit of free content. To safeguard the passengers and electrical equipment, ASME A17.12.8.2.3.2 requires the power source to the elevator control panel to shut down prior to the discharge of water from a sprinkler head. These circuit breaker selective coordination tables can be used to identify the maximum fault current that a pair of circuit breakers can selectively coordinate. If elevators are supplied by the emergency, legally required standby or critical operation power systems, then selective coordination is required per the 2017 NEC in 700.32, 701.27 or 708.54. First, the ATS signals the elevators that it's about to switch over to emergency power preferably 30 sec or more prior to switching, which allows the elevator controller to bring each elevator cab to the nearest landing and stop, thus protecting the motors and electrical system. The branch circuit supplying these units is to be similarly dedicated, with the associated overcurrent device located in the machine room or similar location. Convenience receptacles and lighting for maintenance purposes are required at the base of the pit and, in some instances (elevator manufacturer dependent), at the top of the elevator shaft. Flexible metal, liquid-tight flexible metal or liquid-tight flexible nonmetallic conduit 3/8 in. Next, with multiple elevator banks, the controller will usually allow only one elevator at a time to operate, reducing the amount of emergency power required. Mobile, AL 36606 USA Machine room-less elevator installations incorporate the elevator controller and often the primary disconnecting means in a convenient package that is located within the elevator shaft. Flexible cords and cables part of listed equipment operating at 30 V (42 VDC) or less, similarly supported and protected, jacketed and flame retardant, are permitted. In the event of a breakdown, that phone must automatically call a location staffed 24 hours a day. Such design innovations require sophisticated wiring strategies. Depending on your local codes, you can do this by installing heat or smoke detectors within 24 in. 23.254.250.15 The condition is that all conductors must be insulated for the maximum voltage applied to any conductor within the cables or raceway system, and all live parts of the equipment must be insulated from ground for this maximum voltage. Home Articles Elevator World June 2012 Issue NEC Article 620: Elevators, Part 2. Smoke detectors, which are required in all elevator lobbies and elevator equipment rooms, must be connected to the elevator controllers directly by means of auxiliary contacts and wiring, or indirectly by means of output signals from the fire alarm control panel.
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