poot_traveller said:
Quite a big fuse for 10 AWG. Apparently 10 AWG is good for up to 30 amp fuses. 35 amp fuse is cutting it a bit close for comfort.
Good to see that you are catching on quite well :thumbsup:
I do however wonder which table you are using to get the AWG to AMP guide numbers.
I call the tables and numbers for 'guide numbers', as there are many circumstances to consider, when creating an easy to use table - that will ALWAYS hold true!
For a (I hope) good guide of AWG-to-AMP numbers I usually use this web page:
https://www.powerstream.com/Wire_Size.htm
But I wanted to see if I could find a different table that would say max 30 Amp for a 10 AWG wire.
And this web page does exactly that:
https://www.thespruce.com/matching-wire-size-to-circuit-amperage-1152865
So I think the difference between these two web pages are; one is targeted for use in a house/building, the other gives guidelines for wire use as they are typically being used in the automotive context.
So this makes me wonder why there is the such a difference in the recommended highest design-load of amp for the same AWG size of wire?
I think that, at the core, it is a question of being able to get rid of the heat created in the wire, because of the natural resistance of the wire.
And in buildings wires can typically be very tightly enclosed, and thus, for long stretches, can be in a worst-case scenario, where the guide/code MUST guarantee that the wire simply never ever overheats (= gets warm enough to cause its surroundings to melt or even catch fire).
Where as for wires in a car, they are typically not as enclosed (completely engulfed in insulation, concrete, wood etc.) so they are much more likely to be able to get rid of heat.
Either way, it is always wise to over-size ones wires and connectors.
As a side note on fuses:
For an electronics project I needed to select solutions for wires, connectors, fuses and PCB tracks.
So I did some testing of fuses, and measured things like the voltage loss over the fuse, and monitored the fuse temperature.
Because the car blade fuses are easy to find, I did several tests on blade fuses.
Some of my findings about blade fuses were:
- that the get very hot, when being loaded close to their rated limit. When temperatures got over 90*C (194*F) I stopped measuring, because temperatures like that were useless for my project.
- but for fun I did try to run a 30A fuse at a 30A load for an extended period of time.
After a few minutes I got 110*C (230*F) and I decided to stop, as I had not designed the test space to make sure that high temperaturs would not melt or scar anything.
I then tested the fuse being mounted differently. The first tests had the fuse mounted to a PCB. For the next test I used a fuse-mount-on-a-wire,
and this test gave me much lower temperatures - for the fuse - but several inches of the wire also got quite warm. So I concluded that the wires functioned as a heat sink.
- I was able to run a blade fuse at 30-40% over its rating a very long time, and it would still not blow. It would get hot, very hot indeed, but would not blow.
It typically did not blow until it reached 45-50% over the rating.
This was of cause just one mans testing. Done for some hours, one day. So it is not conclusive of anything much.
I did however learn that all types of fuses get hot. They all depend on melting metal somehow. And I mean literally - melting meta!
So my own conclusion was, that once the heat leaves the fuse, it must have somewhere to go, somewhere to dissipate to, without doing damage, or the entire fuse, fuse holder, connector and/or wire, can get very hot indeed.
Likewise I discovered that blade fuses are what you call slow-blow fuses. So even for a short time overload (<50%) they will not blow, nor will they get damaged (ie. the rating stays the same).
