Why this item instead of a standard fuse?

[Coelacanth]

I've had this thing in the second-from-far-right 20A fuse socket (taillights/cigarette lighter) for as long as I can remember, it was there when I bought the car. Why would someone install this instead of an ordinary 20A fuse?

 

[Unkle Krusty]

The original fuse block on my van, was falling apart. The fittings for the fuses were loose. Not much worked.
For a stock or show car, I would try and fix. Otherwise I prefer the modern fuses.

 

[Coelacanth]

My fuse box is in good condition, here it is after cleaning...I just wonder what that object is and why someone would install that instead of a standard fuse?

 

[R413]

That is a circuit breaker, probably self resetting. So when the problem happens the circuit goes open, when problem goes away and it cools off the circuit is functional again. Intermittent problem they couldn't fond or have time or knowledge to fix it.

Being in the taillight spot would be good to have them come on again without doing anything. Maybe a trailer was involved.

 

[Coelacanth]

Thanks R413 & Sixpactogo, looks like I'll be keeping an eye on the taillights. I don't recall seeing any button on it.

 

[Vaanth]

I've had this thing in the second-from-far-right 20A fuse socket (taillights/cigarette lighter) for as long as I can remember, it was there when I bought the car. Why would someone install this instead of an ordinary 20A fuse?

View attachment 1930444

The pictured item is a snap-in circuit breaker. These breakers mount in standard fuse clips that hold round glass-style fuses.

These breakers automatically reset and continuously cycle during over current conditions or events. It can be used in a circuit that may have spurious events, that might blow a fuse during the event, but the circuit is not really overloaded.

Yours may have been installed to prevent nuisance fuse events, or to mask a potential issue. They have proper uses, and can be convenient, but should be used properly.

The factories used breakers in several areas and used a similar breaker in some situations in fuse blocks, such as the one pictured in the following image:

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[Coelacanth]

Good to know, Vaanth. This summer, I've spent a ton of time going through my wiring, front to back. Eliminating a nest of old wiring from a stereo, speakers and amp I used to have, and cheap (at the time) alarm system. I don't know how many hours I spent staring at 3 different wiring diagrams and images from the FSM, but it's been cathartic to return things to a simpler, more original state. The idea is to get Grendel back to a baseline before I do anything new, electrically.

 

[R413]

They could have used the lighter socket or the lighter wire for accessories and that caused the blown fuse problem. Seems when there is a rats nest of wores these problem go with it.

 

[1 Wild R/T]

Vaanth & R413 are both 100% spot on...

 

[Coelacanth]

The cigarette lighter/accessories might make sense. My car never had a trailer hitch.