Next, the electrician should replicate a zero voltage reading with his voltmeter as per NFPA 70E 120.1(5). While performing electrical LOTO with a voltage detector installed, the electrician can pre-check the internal voltage state without opening the enclosure. Less Voltage Exposure Means Less Arc Flash Risk Without voltage, electrical accidents and arc flashes do not happen.This feature also provides built-in surge immunity. A medium voltage indicator without a hard-wired ground connection eliminates this potential point of failure. A voltage indicator that provides a hard-wired path to ground introduces a high-risk failure point. No 'hard-wired' Ground Connection: A short circuit to ground is a common failure mode with medium voltage equipment.This is important because a device failure is another example of a 'false negative' voltage indication. A robust, long-life design means fewer device failures. Maintenance Free: A medium voltage indicator needs to have a long maintenance-free life (7+ years) because maintenance departments have other priorities than maintaining medium voltage indicators.In this case, a blown fuse creates a 'false-negative' voltage indication. Fuses add more connections and components reducing the overall reliability of the voltage indicator. No fuses: A circuit design of a voltage indicator should not require fusing in order to protect its internal circuitry.Furthermore, failure of the power supply creates a 'false-negative' meaning that voltage exists without indication. Simply put, more stuff means less reliability. Circuit designs relying upon another power supply or battery energizing its circuitry increases the number of components and connections between the 'line voltage' and the 'indicator'. Self-powered circuitry: A voltage indicator connected to a given voltage source has its circuitry powered from the same source (self-powered by line voltage).The following are examples of how the design of a medium voltage indicator minimizes the opportunity for a 'false-negative' to occur: Oppositely, a 'false positive' (voltage indication when voltage does not exist) is completely harmless. This means the voltage detector (falsely) indicated that there was no voltage (negative). Designed for Electrical Safety: No 'False-Negative'When an electrician starts working on an energized conductor that he just tested 'dead' but is actually live, a dangerous situation called a 'false negative' indication is created. The enclosure size and the distance between the adjoining phases will also affect the flash rate. As the voltage increases, more current flows thereby increasing the flash rate.

This means when higher voltages exist the air becomes slightly conductive allowing current to flow 'through the air,' which completes the flashing LED circuit. Energy from the bus flows through the indicator circuit through a capacitive ground connection. How it WorksA medium voltage indicator is a single-phase device mounted onto each phase of a power bus. We will also help you understand how incorporating these devices into a Lock-out Tag-out (LOTO) procedure enhances safety and productivity. Medium voltage indicators (2K-43KVolts) offer positive benefits because this device keeps workers away from voltage and provides an answers the 'Is there voltage?' question.What makes medium voltage indicators suitable to meet the high calling of electrical safety? In this paper, we will get specific on the design, application and installed cost. Without a precise answer to this question, little else matters in electrical safety. Equally important, answering the question, 'Is there voltage?' becomes the other half of the electrical safety equation. Obviously, finding methods of keeping workers away from electrical energy is a key objective for workplace electrical safety. Medium voltage indicators (2K-43KVolts) offer positive benefits because they keep workers away from voltage and provide an answer to the 'Is there voltage?' question.īy Grace Engineered ProductsLive voltage is in every piece of electrical equipment.

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