A few more things before we wrap up discussion on circuit protection devices (CPDs).
The following is the most common symbol used to represent a fuse:
However, there's a wide variety of symbols used to represent fuses, circuit breakers, and just about every other type of electrical circuit component. Use whatever works for you. The important thing is you, and anyone needing to understand your circuit diagrams, knows what the symbols represent. For this reason, I prefer to use text to identify circuit elements, regardless of whatever symbols I'm using.
There are two basic types of CPDs, slow-acting and fast-acting. Slow-acting CPDs have a slight delay before tripping or blowing to handle anticipated brief current surges in appropriate circuits. Fast-acting CPDs are designed to trip or blow very quickly in response to current overloads and are much more common.
With very few exceptions, all CPDs in motor vehicles are fast-acting and are the only type commonly carried in parts stores and automobile departments in other stores. (The few slow-acting CPDs that may exist in motor vehicles all have unique configurations that keep them from being confused with, and used in place of, fast-acting CPDs or vice-versa.)
CPDs sometimes wear out due to age or repeated stress. (One way to "wear out" certain types of circuit breakers is to use them as on-off switches.) CPDs are designed to blow or stay tripped when they fail. So, it's reasonable to replace a blown fuse or reset a circuit breaker once. If the replacement fuse blows or the reset circuit breaker trips again, you have a problem with the circuit. (Repeatedly replacing fuses or resetting circuit breakers is a waste of time, effort, and money … the problem is something other than the CPD so dig in and find the actual problem.)
Finally, in older motor vehicles (like the motorhomes in this thread), there is a third type of CPD -- fusible links. I flat out hate these.
Like fuses, fusible links are single use protection and have to be replaced when they blow. Unfortunately, they look just like all the wires around them and, once you find them, you have to use some type of continuity tester to determine if they've blown.
Likewise, fusible links are very difficult to replace. Rather than copper, they contain a metal with a lower, specific melting point and their amperage rating is based on both their diameter and length. In addition to having to be sure to use the right size and length, trying to solder a replacement into a circuit often causes the link to melt. Furthermore, all but the very best crimp connection creates enough resistance to cause the replacement fusible link to blow. (For these reasons, just about all old-time mechanics hate them.)
Fortunately, reasonably priced high-amperage fuses and circuit breakers have become readily available, rendering fusible links obsolete. Whenever I run across a fusible link, blown or intact, I replace it with a modern fuse or circuit breaker.
