Auxbeam Switch Panel - Wiring Question

[neilkansal]

Hey all,

I recently purchased an auxbeam RA80 switch panel and am looking to wire my lights and other accessories to the panel. I had a question regarding fuse selection that I’m hoping you folks would be able to answer.

the auxbeam panel comes with fuses sized 30, 20, 10, and 5amp. Let’s say I’m wiring an individual Cali raised side projecting ditch light. These are 27 watt/12v gives me a 2.25amp fuse that I would need.

Question 1: would wiring this to a 5amp fuse be a problem?

Question 2: would wiring this to a 20amp fuse be a problem?

Essentially, I’m trying to understand if over-fusing is an issue, and to what extent it would be an issue. I’m trying to make sure I wire this system safely.

Question 3: I’ve seen that you can swap a higher rated fuse out for a lower rated on the auxbeam panel (I.e run a 5amp fuse in a channel that originally had 20amp) Has anyone done this, and any concerns?

Thanks in advance!

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[bakutheleo]

None of what you mention/ask is a concern. More detail:

It is better if the rating of a fuse is relatively close (but higher than) the load. That is, you do not really want a 100A fuse for a 1A load. The fuse is designed to be a safety, so it will not break the connection until its rating is exceeded. But, the max fuse on a circuit is generally set to the rating of the wiring and rest of the system, so even going up to that will not be a problem.

One thing to note--many manufactures lie, exaggerate, or mislead on ratings. With respectable manufacturers you are correct in your 2.25A rating. Some, though, give the watt rating as an "incandescent equivalent," so although they may be giving accurate info in that regard it does not help for current rating. If they state it that way your current is likely around 10% of what you expect (LEDs are roughly 10x as efficient as incandescent). Then I am sure there are others that simply lie. So, to get an accurate current rating it is good to measure it. That said, it will be the number you stated or less, so not really an issue as it is well under any of your fuse ratings.

And yes, you can always install a smaller fuse in a circuit than the original as long as it is rated more than the actual load.

 

[neilkansal]

None of what you mention/ask is a concern. More detail:

It is better if the rating of a fuse is relatively close (but higher than) the load. That is, you do not really want a 100A fuse for a 1A load. The fuse is designed to be a safety, so it will not break the connection until its rating is exceeded. But, the max fuse on a circuit is generally set to the rating of the wiring and rest of the system, so even going up to that will not be a problem.

One thing to note--many manufactures lie, exaggerate, or mislead on ratings. With respectable manufacturers you are correct in your 2.25A rating. Some, though, give the watt rating as an "incandescent equivalent," so although they may be giving accurate info in that regard it does not help for current rating. If they state it that way your current is likely around 10% of what you expect (LEDs are roughly 10x as efficient as incandescent). Then I am sure there are others that simply lie. So, to get an accurate current rating it is good to measure it. That said, it will be the number you stated or less, so not really an issue as it is well under any of your fuse ratings.

And yes, you can always install a smaller fuse in a circuit than the original as long as it is rated more than the actual load.

Thanks for this info, that was very helpful! So maybe I’m thinking about this wrong…

Let’s say I have an accessory drawing 2.25 amps, and it’s hooked up to a 20amp fuse. That would mean that the circuit wouldn’t shut down until it’s allowing 20 amps of current. Let’s say something were to go wrong with that accessory and it starts drawing 5-10+ amps. Wouldn’t this become a risk as the wiring for an accessory with that draw probably can’t sustain that much current without melting/becoming a fire risk?

 

[bakutheleo]

Yep, pretty much correct. That is why I mention ideal fuse size is a bit over the actual load (you want a little buffer). That said, usually a failure is a short circuit, so even a relatively large fuse will break the circuit fairly quickly. Wires can handle a much higher load than rated for a short time before they really get too hot. Also the length makes a difference--you can use a much smaller gauge wire for a 6" pigtail than a 10' run.

In your example, if the load is 2.25A, you could put in a 5, 7.5, or 10A fuse and be fine as well.

One more thing...some devices, primarily motors but also many electronic loads, draw a lot more current on startup (called a surge current). To handle that the fuse has to be either enough larger than the running current or be a "slow-blow" version (I do not believe that is common in autos, but I could be wrong). A "slow blow" fuse (or breaker) allows a much larger surge current for a brief amount of time, where a normal fuse will break very quickly. I do not expect LED lights, though, to have a significant surge current.

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