Which of the following defines the conditions for using Type 3 surge protective devices?

Type 3 surge protective devices (SPDs) are specifically designed for installation at the service entrance or at branch panels and are intended to protect equipment from transient voltage spikes that may enter through power lines. These devices are versatile in their placement and can be utilized in subpanels, which allows for added protection at various points in an electrical system.

Installing Type 3 SPDs in subpanels is beneficial because it helps manage surge protection closer to sensitive equipment, thus reducing the risk of damage due to voltage transients. These devices can be placed away from the main panel as long as they are within an appropriate distance to effectively protect the connected loads. This flexibility in installation is one of the defining features of these devices, making it possible to enhance surge protection without strict limitations regarding their proximity to the main panel.

The other options present limitations or conditions that do not accurately reflect the intended use and installation capabilities of Type 3 SPDs. For instance, while some surge protective devices need to be installed in specific locations like within the main panel, Type 3 SPDs allow for broader placement options, including subpanels. This adaptability is essential for ensuring comprehensive surge protection throughout an electrical system.