PV fuse incredibly HOT!

[BradCagle]

30A MidNite solar fuse https://www.amazon.com/dp/B07ND37CVH?ref=ppx_yo2ov_dt_b_product_details&th=1

I noticed today the smell of plastic cooking, nothing melted yet but realized my DIN mounted https://www.amazon.com/gp/product/B009EO8D0C/ref=ox_sc_act_title_18?smid=ATVPDKIKX0DER&psc=1
fuse block was incredibly hot. Hot enough to burn your fingers pretty bad.

My first though was cheap fuse holder, so I flipped the PV disconnect, and pulled the fuse, it's the fuse itself that is the heat source, you can't touch it.

30A Fuse, only 25amp was flowing through it.

Anyone experience this?

 

[Bud Martin]

How many fuses do you have in your combiner box, and only one fuse gets hot?

 

[timselectric]

A bad connection can generate a lot of heat.

 

[BradCagle]

How many fuses do you have in your combiner box, and only one fuse gets hot?

Only one fuse right now, will be adding more strings soon.

 

[BradCagle]

A bad connection can generate a lot of heat.

Very true.

At this point I'm contemplating getting a midnight fuse holder, or just a midnight 30a breaker.

I can see on the fuse that the holder is making very good contact, and it clicks in with solid force. But the metal used in the holder could just be total garbage for electrical conductivity.

 

[timselectric]

I prefer breakers, if feasible.

 

[BradCagle]

I prefer breakers, if feasible.

Yeah, I think that's the way so I just ordered this https://www.amazon.com/gp/product/B004EQJS1S/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

[chrisski]

I found that it can take a little for my wires to settle in the circuit breaker. A seven strand round PV wire placed into a flat Type clamp connection can be tight, but when I go back a few months later, as settled somewhat and can be tightened.

How does your fuse holder tighten the wire? Flat head screw? I can't tell from the pick.

 

[BradCagle]

I found that it can take a little for my wires to settle in the circuit breaker. A seven strand round PV wire placed into a flat Type clamp connection can be tight, but when I go back a few months later, as settled somewhat and can be tightened.

How does your fuse holder tighten the wire? Flat head screw? I can't tell from the pick.

it's a phillips, the terminal is a flat type clamp like you mentioned. I really think is the fuse getting hot because when I pulled it out, it was considerably hotter than everything else. Also when I was touching the fuse holder while operating the bulk of the heat was coming from the direct center of the holder where the fuse is.

 

[chrisski]

FWIW, the product is 10 years old, and on amazon the vendor only has 33 reviews for the fuse holder over two years. 31 review are 5 star and 2 reviews are 2 star. Nothing lower. Not sure if this is a red flag or not.

 

[BradCagle]

Alright I have the MidNite MNEPV30 breaker installed, and a MNEPV15 installed on another string. They are wayyyy cooler than the fuses.
So these will be my go to from now on.

https://www.amazon.com/gp/product/B004EQJS1S/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

[copec]

The fuse elements themselves don’t have enough area to transfer heat to make a greater area really hot without the element being hot enough to burn out. I say 95% chance it’s a bad connection.

 

[OzSolar]

When I do a new system its my standard practice to get the entire system up to full load then carefully start measuring voltage drop across the entire system but more importantly across each component. .3 volts doesn't sound like much, right? It could be.... 100 amps will generate 30 watts of heat. .3v x 100a = 30 watts

 

[BradCagle]

The fuse elements themselves don’t have enough area to transfer heat to make a greater area really hot without the element being hot enough to burn out. I say 95% chance it’s a bad connection.

I might do some tests to see if its the fuse, or the holder.

 

[Fingers]

My inline fuse holder melted due to a bad connection, looking at it just now, the crown dropped off!

My rule of thumb now is to buy items with known western brand names, even if the item is manufactured in China, as they have a reputation to uphold. I now turn away from the unknown or unbranded items.

Just looked at your fuse holder, are you aware it's for AC? There's a red light on the front off it probably with a little ac circuitry.
Your producing 30amps at what voltage, and 380v is the max of the holder.

Maybe I'm nit picking, but 30 amps through a 32amp holder, I would try to get a larger margin for error and go for a higher rated holder.

Lol, I have bought ac holders too, not even for the correct size fuse. Haven't used them though. That's what happens when I buy things at midnight zzzZZZZ, zzzZZZZ

 

[BradCagle]

My inline fuse holder melted due to a bad connection, looking at it just now, the crown dropped off!

My rule of thumb now is to buy items with known western brand names, even if the item is manufactured in China, as they have a reputation to uphold. I now turn away from the unknown or unbranded items.

Just looked at your fuse holder, are you aware it's for AC? There's a red light on the front off it probably with a little ac circuitry.
Your producing 30amps at what voltage, and 380v is the max of the holder.

Maybe I'm nit picking, but 30 amps through a 32amp holder, I would try to get a larger margin for error and go for a higher rated holder.

Lol, I have bought ac holders too, not even for the correct size fuse. Haven't used them though. That's what happens when I buy things at midnight zzzZZZZ, zzzZZZZ

Well the fuse was a name brand. But the holder is no-name Chinese.

Voltage was around 65vdc

I'm really pretty sure the heat was coming from the fuse. Eventually I'd like to run an experiment to test if its the fuse getting hot.

I've switched to midnight breakers, and have had no problem since.