I'm evaluating an electrical enclosure for a power-plant. Power plants are not required to follow CSA standards, however this electrical enclosure does anyway. Upstream of the enclosure is a rated breaker, and this is what is currently defined as the 'branch.' However, inside of the enclosure there are several elements being powered in parallel, with supplementary breakers for over-current protection. The issue was raised as to whether these parallel loads also required branch rated breakers, and my research into the issue says this by and large depends on whether these parallel loads are considered branches or not. Branches require rated breakers for short circuit protection is the long and short of it. My biggest problem with the definition is the fact that it almost always makes reference to a breaker, or an outlet. Since the code requires all branch circuits to have branch rated protection, it gets confusing when that same protection enters the definition of the branch. I'll give you a few examples When I found that last one it seemed like assuming the entire enclosure was a single branch was legitimate. But I haven't found anything reaffirming that, and I haven't managed to find an adequate definition in any of the codes I've looked at, primarily the Canadian Electrical Code, which defines it as: Fairly similar to the previous. Can anyone shed some light on this definition?