Should I put the fuse on the negative battery terminal?

[Solar254]

If electrons, which form the electrical current and have a negative charge, do move from the negative battery terminal to the positive terminal, does this mean that the fuse should be on the negative battery side and not the positive terminal?

 

[hwy17]

The current is the same on both sides so either works.

 

[chrisski]

You fuse it so the circuit is not complete. Check the wiring to be sure the circuit is interrupted when the fuse blows. Many pathways to ground on the negative side.

I’d only fuse on the negative side for a positive ground, and I have no reason to build that .

 

[timselectric]

I'm positive on where you should put the fuse. lol

 

[42OhmsPA]

I'm positive on where you should put the fuse. lol

+ 1​

 

[apctjb]

Unless battery negative is somehow considered neutral in your system, I don't see why it matters, current flow will be interrupted (assuming a correctly rated interrupt device is used.)

 

[timselectric]

It depends on what system you are using.
If the DC systems are fully isolated, then the protection can be on either polarity.
If not fully isolated, it must be on the positive. Because the negatives are common.
If you are not sure if they are isolated. Put it on the positive. And you are covered either way.

 

[LydMekk]

Aaand in this place we LIKE overkill ...so I fuse both the pos and the neg on my batteries.
/sleepbetteratnight ^^

 

[webbbn]

Many pathways to ground on the negative side.

This is all that matters. You need to ensure that the fuse is on the only pathway to the source that you're trying to isolate. If you put the fuse on negative and have anything else connected to that negative terminal before the fuse, assuming it's "ground", you're going to have problems.

That's a very common problem with low-side MOSFETs. I've been bitten by this at least once with my 3D printers. Using a low-side MOSFET switch controlled by the Pi to switch power to the printer, and then powering the Pi with the same power supply. Turn off the MOSFET, and the printer is more than happy to pull all the current through the Pi until it starts to smoke.

 

[wildbillpdx]

So...I have 200a breaker on positive and I have a 200a T-Class fuse available. Any problem attaching it negative? Would seem based on other posts here that should be okay.

 

[chrisski]

So...I have 200a breaker on positive and I have a 200a T-Class fuse available. Any problem attaching it negative? Would seem based on other posts here that should be okay.

If you place it on the negative, You'd need to be sure it would work with all the pathways to ground. Don't want it blowing and then the current swaps to an even smaller wire to chassis ground path. Since mods will get made in the future, I'd stick to positive even if it was good now.

 

[Skypower]

It’s what I did. The fuse block made a convenient terminal. That usb adapter
Is isolated so if the fuse goes the power is cut beyond the battery.