time2roll wrote:
50 amp fuse close to the battery or power source. I agree with #8 unless the distance is long go #6 wire.
Fuse to the wire size, the idea is to protect the wire not the device hung on the wire.
SEE HERE"Why use a fuse?
A fuse provides a safe and cost effective way to protect an electrical device or installation from electrical overloads which could damage components or wiring and potentially cause a fire."Basically you want the fuse to blow out in a controlled manor well before the entire wire becomes a fuse.
Per
HERE"Fuses normally protect wires from burning and setting fire to things"Per
HERE"When specifying a fuse for an after-market application, the key consideration is that the fuse should be the weakest point (i.e. lowest rated component) so that it always blows before any damage occurs to other parts of the electrical circuit. However, you also do not want the fuse to keep blowing under normal operation (known as a nuisance blow), so the two elements to consider are:
The current rating of the smallest cable in the circuit
The current draw on the circuit under normal expected operating conditions
The fuse rating should lie somewhere between these two values to allow normal operation but blow on overload. For example, if the normal expected current draw is 10A and the cable size is 25A, then a fuse rated at 15A would be appropriate."50A fuse would be for 6Ga wire, not for 8ga-26ga wire.
Granted, bare UNinsulated wire can sustain higher current than insulated wire, but, it isn't like one is going to install and use UNinsulated wire for this use.
Where to place the fuse?
Generally, as close to the power source (IE 12V battery in the case of the OPs situation) as possible, I have often seen references of 18" or closer to the battery..
On edit..
I will also add that if you have wire which has more capacity than the expected load, you can use a lower amperage fuse.
In other words, if you had 8 ga wire which would typically be fused at 40A but your device (like a 400W inverter) draws 35A at max full load you could fuse to the max load of the inverter which would be 35A.. But cut that too close and you may get nuisance blown fuses..
The idea of using larger wire sizes than needed is not to handle more current, but to lower the voltage drop seen by the inverter.. Just .1V extra drop in the wire can make the difference between the inverter working or shutting down in 12V systems.
