Electrical question, do I need a circuit breaker?

Hello, considering adding a few additional lights (led bar, back up lights, and bed lights, already have PIAA 520's) I am going to add a blue sea fuse box but after searching around most seem to add a circuit breaker. I will admit I don't understand why you need to add a breaker if you already have fuses. The limited info I found said to get a 100 amp breaker. Can someone please enlighten me.
Thanks!

 

I would guess so you could shut off the added fuse panel completely if you ever wanted to?

So far I've got 520's and 540's run off the main fuse panel using in-line fuses. I wouldn't hesitate to add another pair of lights without a fuse box or ciruit breaker. I can't imagine the LED's would have a whole lot of draw so I'd go with not required for that kind of loading. If you have a winch, 8 lights across the front, bed lights and an LED bar on the roof that might be another case.

 

Thanks, so besides being able to isolate the add-on's what purpose does it serve? It's only another $45 ish but if I don't need to.

 

I'd PM one of the other members you saw running a circuit breaker and ask why. For your use, that doesn't seem like an excessive amount of added draw so I can't see a need for the circuit breaker. I've got (and been operating for a couple years) almost as much draw as you will have and don't even have the added fuse panel.

 

Thanks Mike! The only reason i'm thinking of adding fuse panel in to keep it organized.

 

If could start over again, I'd add the fuse panel like you're doing. I just kept adding things one at a time and now I have an organized rat's nest of wiring in the under hood fuse box. I only planned to have 1 pair of lights, then I found TW, I now have 3 pairs of lights...

 

A fuse or breaker is there to protect the wiring or components that are down stream of the fuse or breaker. If the fuse block is rated at a max of 100amps then it could make sense to install a breaker before the fuse block. On the other hand, if all the fuses downstream of the block add up to less than the fuse block is rated for, then it's not needed.

I've done aux fuse blocks before. I don't use a breaker. Here's why: I don't add more amp draw than the block is rated for, and there is usually nowhere to mount the breaker right at the battery. There is a length of cable from the battery to the breaker. With or without the breaker, there will be an unfused cable, unless you can mount the breaker ON the battery.

Does that make sense?

You also have an unfused length of battery cable from the battery to the starter. As long as you protect the cable running to the fuse block from damage and secure it well, there is no difference between the two. On the other hand, if you mount a breaker on the fender and run a battery cable from the battery to your breaker and you do a poor job of it, if the cable shorts out before the breaker, you have a serious problem.