An electron configuration shows the electrons distribution by sublevel using the quantum numbers n and l, where the notation for l is by its letter designation (s, p, d, f, etc. For example, the notation 3 d4 indicates 4 electrons in the d sublevel (l =2) of. What do numbers like “20A” or “15A” mean on breaker labels? It is normal to feel unsure about your distribution box. The labels might look confusing at first. You can learn what they mean with some help. This also helps. A distribution box is a key part of electrical systems in buildings. Inside, you'll find parts like circuit breakers and fuses that protect the system from problems like overloads and short circuits. Check electrical parameters: First understand the basic electrical parameters of Distribution box so that you can have a general understanding of the capacity and performance of the distribution box. A wrong code can trigger unexpected tax bills, early.