The Point of Fuses

Battery cable to the inverter rubs against a grounded metal frame until insulation is breached. Boom, 5000 amps of short circuit current is delivered in a most energetic fashion.

Bruce

roam1 wrote:
Depends on where the fuse is.
If its near the power source like the battery or the distribution panel, it is there to protect the wiring. That wiring may be supporting many devices, like lights, sensors, stereo......If it is near the device, like the small fuse near your radio, it is there to protect the device. Both are prudent!

Sorry I've been absent here but this seems like the most reasonable explanation for having a fuse. I don't have a fuse on the converter output. I do have one on the battery output but it's sized for the inverter load. I will say I'm still confused on the need for a catastrophic fuse cause I don't understand how a shorted battery can send current outside of the battery if there's no device to draw it. Can someone explain that one?

Pauljdav wrote:
No fuse and the worst thing that will happen?
Fire, The battery would put out enough amps to cause a fire if the wire shorted to the trailer frame.

While working on my steps this winter I kept blowing 15 amp fuses to my ignition wire. After much searching using long wires and alligator clips I traced wire from the fuse box to the point of origin I never saw the problem until I opened my slide and found the wire had been caught by the slide mechanism and grounded to the frame. The mechanism was also rubbing on my house battery cable which could have had the same fate. I never would have thought about this as a problem until it happened to me.

Depends on where the fuse is.
If its near the power source like the battery or the distribution panel, it is there to protect the wiring. That wiring may be supporting many devices, like lights, sensors, stereo......If it is near the device, like the small fuse near your radio, it is there to protect the device. Both are prudent!

4' in plain sight, well protected and no danger you can skip the fuse IMO.
But a catastrophic failure would be a massive internal short and at least 900 amps available from the battery to push the magic smoke out.

No fuse and the worst thing that will happen?
Fire, The battery would put out enough amps to cause a fire if the wire shorted to the trailer frame.

Electricity is made of smoke, when the smoke leaks out it does not work.

But seriously, where there is smoke there can be fire, the fuse protects you from the potential of fire from a dead short.

MEXICOWANDERER wrote:
"What Is The WORST Thing That Can Happen?"

Is the prime directive of electrical safety design.

At one time there were special breakers that supposedly could detect arcing while current still was under the max amp trip point, and break the circuit. I've been out of circulation too long I guess. I do not know if these breakers were successful and if they still exist.

Is this what you are referring to? Arc Fault breaker

They are required on bedroom circuits where I live.

mena661 wrote:
Fuses are to protect wiring, correct? If that is really so then I have a question posed as an example. Suppose I have a 55 amp converter. It is connected to a bank of batteries with 4 ft of #4 wire. ~180 amps is the max rating for 105C #4 wiring. What would be the point of fusing this wire if a catastrophic failure of the unit only sends a max of 55 amps down the wire?

The converter side is rarely fused, because the converter is inherently current limited.
The battery side is always fused though.