HRC fuses any good?
Fingers Registered Users Posts: 19 ✭✭
Hello all, my first posting here
I'm wondering about what fuse types we can use for our off grid systems.
I used a Chinese 15amp in line fuse, with the solar panel power of about 160 volts - 9amps. Actually it wasn't anywhere near that as the weather was awful that week. Anyhow the fuse holder melted, no doubt if it had been good weather I may well have had a fire on my hands.
This prompted me into getting rid of my Chinese fuses, trips and switches, and replace them with industrial "fused switch boxes".
The small switch box is 32amp for my panels to charge controller, and the large box is 100amp (fitted with a 160amp fuse), for battery to 48volt 6kw inverter.
Ok, here's the question, are HRC fuses any good for our needs?
All I know about them is they are ultra safe. But unfortunately I haven't seen any fuses with DC on them.
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For example, here is a simple knife switch with 220 VAC vs 220 VDC volts:
DC arcs (typically over 12 VDC) just sustain much better (or worst--depending on your needs) than AC arcs.
Here is a good discussion on how to pick DC fuses/breakers for your system:
Good quality fuses and circuit breakers, rated for application, are the only way to go to help limit the possibility of fire in your power system. Battery Banks are huge source of current, and any bank over ~12 VDC (roughly the minimum voltage required to sustain an arc--varies a bit based the material being being turned into a plasma), should really use breakers (sort of preferred--Can also be used as a handy on/off switch for circuits--vs fuses and fuse holders which should not be used to switch on/off current).
Remember that fuses/breakers are their to protect your wiring and your devices from catching fire. OCPDs (over current protective devices) are not their to "save" your inverter or charge controller from damage (i.e., device may still short circuit from over voltage, lightning, or other issues, but OCPDs are not there to "save" the device from internal damage).
Fuses+fuse holders+spare fuses that are rated for high current are not usually much cheaper than a good quality circuit breaker which is also useful as an on/off switch. However, fuses and holders can be much smaller than a typical full size circuit breaker.
Not all fuse and fuse holders are "good quality" and design... For example, the automotive fuse holders and fuses you see everywhere--I would suggest staying away from them. They have been known to overheat and melt the holders even with less than rated current.
Example (know nothing about this specific brand/holder--Just an example of "automotive" fuse and holder):