What method is used on an outside pipe to prevent it from freezing?

The most effective method for preventing an outside pipe from freezing is using heat tape. Heat tape is specifically designed for this purpose; it consists of an electrical heating element that is applied directly to the pipe surface. When activated, it generates heat, which helps maintain the pipe's temperature above freezing, even in cold weather conditions.

Heat tape can help protect pipes from freezing and bursting, which can lead to significant damage and costly repairs. It's crucial to properly install the heat tape according to the manufacturer's instructions to ensure its effectiveness and safety. This preventative measure is often used in residential and commercial applications where pipe freezing is a risk due to low temperatures.

Insulation can provide some thermal resistance and slow down heat loss, but it is not as direct or effective as heat tape. Similarly, a resistor does not directly provide heating; instead, it merely opposes current flow which isn’t useful in the context of preventing pipe freezing. Heating cables can also serve as a viable option for heat distribution, but heat tape is more commonly recognized for this specific application.