Is an amp an amp?

Good question. I would assume the inverter has internal protection but it would be a good idea to check the manual.

It is probably fused on the input side. A short on the output side would kill the inverter unless they have current limiting. A fuse on the output would protect the inverter.

wanderingbob wrote:
My 3,500 watt inverter is not fused on the output side . I assume if a short happens all 30 some amps would flow to the short . Right ?
Would an inline fuse as you use in a D.C. circuit work ? Would a fuse designed for a D.C. circuit blow at the same amperage ?

An amp is an amp, but not all fuses are the same. The output on your inverter is 115 volts more or less, so you need a fuse rated for at least that voltage. Larger DC fuses are usually rated for 32v which isn't enough. Smaller glass fuses are sometimes rated for 250vac but I think they max out at 15a.

Strange that your inverter has no circuit breaker on the output. As I recall my Magnum has two, one for AC input and one for AC output.

Most inverter installations call for a high amp, slow-burn fuse on the positive lead as close to the battery as practical.

And, while an amp is an amp, a 3500 watt inverter can pull 3500 divided by 12 volts= 292 amps @ 12 VDC.

x2 for Wolfe10's advice... and to add, for an inverter that size, you probably have a BIG battery bank, and for that, you'll want to use no less than a CLASS T fuse.

A big battery bank can deliver over 10,000 amps into a short, which will jump right over a blown ANL or AGC fuse. The class T design has the fuse element protected by an extinguishing material preventing the arc from sustaining itself and causing further damage. AGC and ANL rely on an air gap, which does nothing to extinguish a high current arc.

Use circuit breakers on the output side, sized according to what you are connecting them to. Usually an inverter that large feeds the main panel in your RV via a transfer switch.

Owner installed . I just searched on line and it sez each circuit has a 30 amp fuse inside . It is in my toyhauler and will run my table saw and such . I just installed a small freezer and it seems to run OK . Maybe I worry to much ! The batt bank has a 250 amp inline fuse . We may quit the wood craft business and walk the earth for a year , walkabout !