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close this bookProtective Measures against Hazardous Contact Voltage - Course: Basic skills and knowledge of electrical engineering. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 23 p.)
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View the documentIntroduction
View the document1. The Necessity of Protective Measures against Hazardous Contact Voltage
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1. The Necessity of Protective Measures against Hazardous Contact Voltage

The protection of human life, health and capacity for work is a basic human concern. Therefore, in electrical plants with or without earthed net point, it is necessary to take protective measures against hazardous contact voltage if the conductor-earth voltage exceeds

- 50 V with alternating current or
- 120 V with direct current!

Accidents due to electricity are often caused by improper installation or missing and/or defective protective measures.

Manufactures of electrical equipment are obliged to insulate this equipment for the respective working voltage.

Why is it still necessary to take protective measures, even if cables, electrical equipment and plants are sufficiently insulated?


The protection of man against hazardous contact voltage has priority over function!