Class t fuse without holder

[dielectric]

Compactness is the reason I'm looking for inline fuse install.
I did buy that $70 class T ignition proof holder. It's bulky.
and load on bat. terminal is increased not reduced by that thing.
If I had one inline then 2 SHORT wires would be flexing instead of just one.
After searching a bit more, I think I might just 3d print the minimal version of it with just 2 bolts.
Here is a UL listed but not class T small part https://www.littelfuse.com/data/en/data_sheets/littelfuse-fuseblock-lffb003.pdf
it's about half the price (for those budget-conscious of us), but NOT class T.

I can print something like that for the class T fuse I got from amazon, basically a bar with right spacing for the 2 bolts.

However, does anyone know what happens when class T blows ?
Does it mechanically separate ? Is "everything" contained inside the ceramic tube?
If the arch and it's extinguishing is completely contained and the fuse does not change it's outer dimensions then not having a holder seems a valid option.
I might still print one, but having complete information and not conjecture is always preferable.

Thank you.

 

[Hedges]

We expect everything to be contained, and the tube to not separate. It is meant to interrupt severe AC loads, like 200,000A AC.
But integrity might be compromised, and if you're concerned about stress on battery terminal from cables, you should also be concerned about the body of a blown fuse.

A short fine-stranded cable from battery to fuse holder solidly mounted would be ideal.

If you're going to do in-line without fuse holder, consider securing positive cable such that of broken at fuse it can't contact anything, and secure negative so it can't contact positive.

There are videos of lesser fuses exploding and burning a test dummy, showing that enclosure (and better fuses) are desirable. At least for those high-energy events like 200,000A fault current in 300Vrms system. Your battery is much less, but may continue conducing longer than 0.008 seconds.

 

[dielectric]

We expect everything to be contained, and the tube to not separate. It is meant to interrupt severe AC loads, like 200,000A AC.
But integrity might be compromised, and if you're concerned about stress on battery terminal from cables, you should also be concerned about the body of a blown fuse.

A short fine-stranded cable from battery to fuse holder solidly mounted would be ideal.

If you're going to do in-line without fuse holder, consider securing positive cable such that of broken at fuse it can't contact anything, and secure negative so it can't contact positive.

There are videos of lesser fuses exploding and burning a test dummy, showing that enclosure (and better fuses) are desirable. At least for those high-energy events like 200,000A fault current in 300Vrms system. Your battery is much less, but may continue conducing longer than 0.008 seconds.

Thanks, this is great to know. I absolutely agree on all your points.

and the wires I'm going to use are 2/0 (because overbuilding and worried more about robustness than expense)
they are very fine-stranded
But trying to fit everything in compactly the wires are only about 4" long. Together 8" of "flexibility" is better than 4.

After contemplating a 3d printed a (not very high temp resistant holder) I think a better inline option would be a thick piece of FR4 with just 2 holes/bolts seems very simple and should keep wires attached in the same place even if fuse is somewhat weakened.


thanks again for the info

 

[Hedges]

That should work. But if not secured, could move to the point of shorting to something, so second piece of FR4 could make cover.
Bolt threaded long enough for everything, and pair of nuts clamps fuse down onto ring terminal.
you just have to avoid cable flipping lose during fuse replacement. Cable ties might keep it on the FR4.

 

[nlewis1111]

Best strategy as far as I can tell, in these times of shortage, it to buy the holder and fuse together, and several spares to fit the holder. All at once. T fuses of a particular size are a pain to find these days.

Seems ridiculous. It's just a hunk of metal with a few machined holes. And the fuse ain't rocket science.

 

[Hedges]

And UL listing.

Supply chain has been in bad shape lately, the result of everybody seeking best margins.
Some transistors I saw had 5 year lead time. Some chokes 1 year.

Fuses matter. Having the right fuse or breaker can prevent major damage.

I've bought used breakers and found some trip below rating. Top name brand, so it is a matter of them aging.
Maybe used fuses work out better? For instance:

Bussmann JJN-100 Amp Fuse Class T 300 VAC 300V a.c. IR 200kA 160V d.c. 20kA | eBay

Find many great new & used options and get the best deals for Bussmann JJN-100 Amp Fuse Class T 300 VAC 300V a.c. IR 200kA 160V d.c. 20kA at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[SparkyJJO]

Just have to keep your eyes open and check back often for used ones. When I got my fuses, brand new from shunts.com was cheaper than used from fleabay, for whatever reason.

 

[Danke]

Used fuse? like blown one?