What is the primary electrical hazard when contacting 100-200 mA?

The primary electrical hazard when encountering currents in the range of 100-200 mA is heart failure. Currents at this level can cause severe disruptions in the electrical signals that regulate the heartbeat, leading to conditions such as ventricular fibrillation, which can halt the heart's pumping action. This is particularly dangerous because the heart relies on precise electrical signals to maintain an effective rhythm; when these signals are disrupted by an electrical current, the heart may not be able to effectively circulate blood throughout the body, putting the individual at severe risk of cardiovascular collapse or even death.

While muscle contractions and other issues like burns or respiratory failure can occur with exposure to electrical currents, the immediate and most critical risk in this amperage range is indeed heart failure, as it poses the most significant threat to life. Understanding this risk emphasizes the importance of electrical safety and taking necessary precautions when working with or near electrical systems.