XL-21, XRM101 series distribution box are suitable for indoor three-phase five-wire low-voltage distribution system, rated voltage of AC 220/380V, rated current of 16A~630A and below, rated frequency of 50Hz, as the use of receiving and distributing electric energy. With the improvement of electrical. In this guide, we'll break down the 12 main types of distribution boxes in a way that's easy to understand. We'll chat about what each one does, where it shines, and then dive into how to choose the perfect box for your needs. Main Distribution Board (MDB) 2.