Fuse Block Confusion

[liteyear98]

I bought a Go Power fuse block (Go Power! FBL-200 Class T 200 Amp Fuse with Block ) from amazon, but received something like a Thor fuse block (4 screw holes and different clip type for cover).
The one I received has the terminal lugs flat against the base vs the elevated lugs seen in the pic. (This seems a bit more sturdy to me)

I am looking change my current fuse setup (I am already using a dual terminal MBRF for input from CC and out to Inverter) for my battery bank for 175A (2/0 Welding cable and 24v battery bank) and want to make sure I am using the correct fuse block as I may want too expand my battery bank and/or use a different size inverter (Smaller load / Smaller fuse).

Question: Will different AMP rated fuses fit this type of fuse block?

Note: I am not trying to over or under size the fuse - I just want to be in the "know" so that I am being safe and doing things right.

Why I ask what fuses fir this block:
The spec sheet says... "The class T fuses range from 110 to 400 amps. One block size fits all fuses and the wiring range is #6 to 4/0."

But....
I was under the impression from reading the Class T fuses had different mounting hole dimensions based on their AMP rating.

Looking at the spec sheet for the go power fuse block I ordered, the dimensions from Center hole to center hole of the JLLN series fuses are:
70A-100A - 39.7mm
110A-200A - 42.9mm
225A-400A - 46.8mm

Maybe there is enough wiggle room for fuses of different ratings to mount, but that seems dangerous to me, as you could potentially put a 300A fuse on a wire not rated for that much and cause little flamey things to occur?


Pics for reference

Go Power

Go Power.jpg
Thor type

Thor type.jpg

[liteyear98]

I think I have the solution....
If my fuse does blow for whatever reason, I could just get a replacement and if it doesnt fit the holder because the Class T fuses have different dimensions based on their amperage rating... I could just bolt the fuse to the battery terminal and bolt the cable to the other end of the fuse.

[DrLumen]

Hard to tell for sure but for the bottom one it appears the lugs slide in the carrier to accommodate longer fuses. The top one may just have a slot for the bolt to slip back and forth for larger fuses.

As long as the nut and washer is large enough to not slip through the whole you should be ok. If nothing else you could use (or they may include) a larger washer.

[liteyear98]

The lugs in the block are fixed and cannot move (expand / contract in length)
I really dont think bolting the fuse to the battery is an option - I hoped that would trigger a pro into saying "Hold on Podna...." But maybe they just dont know either?

Assumptions
UL/Ce certified fuse blocks should only be used with the correct fuse? Does this make sense? As I am thinking if you could jam any fuse into a fuse holder, you could end up over or under fusing - leading to blown fuses or melted wire / or possibly exceeding the rating of the block and causing a melt down?

From what I read on the spec sheet (link above) it looks like the fuses increase about 3mm in length when you increase amperage category range.


I was honestly hoping one of the experts would be able to just come out and say that Class T fuses are different lengths and I might need a different fuse block should I go up or down in AMP pull.


At this point, the only "real" way I have other than reading a spec sheet and trusting what I read, or having on of the pro's here confirm my thoughts is to buy a fuse and see for myself.

So I guess will buy a lower amp fuse (70A-100A - 39.7mm) and report back if it is shorter.


... I am very new to solar and have spent many, many hours reading, learning and experimenting from Harbor Freight up to multiple 72 panel 320 watt panels. I would like to move my question above into my personal knowledge bank of .... "OK, I know for sure that I need an XXX amp fuse block for xxx scenario".

[Gdwats]

Me too, weak on fusing and charge distribution blocks. Need to learn.

[Mike90250]

Me too, weak on fusing and charge distribution blocks. Need to learn.

First lesson, Don't get parts at automotive stores. They are generally cheap, and if you get a 30A fuse & holder, it starts melting at 20amps. They just are not well made. Maybe parts from a auto stereo store would be ok, those are often heavier duty and may last, Parts from Marine Supply centers are usually very well built and hold up,

Fuses are to protect the wires from bursting into flame, if a problem in the wire develops. Circuit breakers protect like fuses, and many are able to function as a switch to turn circuits off and on.. For Solar, there are special DC circuit breakers, standard household AC breakers will not reliably work on DC.

[sensij]

At this point, the only "real" way I have other than reading a spec sheet and trusting what I read, or having on of the pro's here confirm my thoughts is to buy a fuse and see for myself.

So I guess will buy a lower amp fuse (70A-100A - 39.7mm) and report back if it is shorter.


... I am very new to solar and have spent many, many hours reading, learning and experimenting from Harbor Freight up to multiple 72 panel 320 watt panels. I would like to move my question above into my personal knowledge bank of .... "OK, I know for sure that I need an XXX amp fuse block for xxx scenario".

I'm having a hard time figuring out what your question is. The Go Power! fuse block datasheet says that it is compatible with Class T from 110 A to 400 A. I am not familiar with that particular fuse block, but in my experience with other brands, if you stick to the compatibility published on the datasheet it will work.

Yes, Class T fuse dimensions change at different amperage levels. As amperage goes up, in addition to getting longer, they get larger in diameter. The hole size also increases, which mitigates some of the change in center to center distance, so a pair of fixed studs can be used across a few amperage ranges if the stud diameter is small enough. The electrical contact is made by the clamping surfaces, so any looseness with respect to the fit of the stud is inconsequential as long as the correct nuts and washers are used and tightened properly.

Please don't hang the fuse off the terminal unsupported. That is a terrible idea... no mechanical support, no electrical insulation, etc, etc.

There is very little in electrical equipment that is fully dummy proof. Nothing except knowledge would stop you from putting a 400 A fuse into that block, and using #6 wire, which is not properly protected by that fuse.

This forum has its share of solar installers, DIY types, professionals in electrical and engineering fields who are hobbyists but able to contribute their knowledge. This is not a forum like HVAC-Talk or Mike Holt, owned and operated by industry professionals for the benefit of professionals, so please don't expect the same kind of technical vetting. Especially on topics of safety, you'll find a lot of caution in the responses, because no one wants you to misunderstand or misapply advice that is given and find yourself in a bad way. There is a basic level of electrical awareness and safety practice that must be understood before you get too far into your solar project, and if your questions or comments demonstrate too much ignorance of that, it isn't reasonable to expect this community to fix that for you.

[liteyear98]

I'm having a hard time figuring out what your question is.

My question is in the OP.... Question: Will different AMP rated fuses fit this type of fuse block?

The Go Power! fuse block datasheet says that it is compatible with Class T from 110 A to 400 A. I am not familiar with that particular fuse block, but in my experience with other brands, if you stick to the compatibility published on the datasheet it will work.

Please take a look at the data sheet rating JPEG attached - 110 - 400 seems to be for 12v now that I look at it? So, maybe this fuse block is only good for certain amerages at different voltage levels?
Rating.JPG
This is why I asked about Class T fuses - Someone could put a 400A fuse on it at 48v, which would be above spec?

The attached PDF shows dimensions from hole to hole (Page 2, Fig 3 Dimension B)

Yes, Class T fuse dimensions change at different amperage levels. As amperage goes up, in addition to getting longer, they get larger in diameter. The hole size also increases, which mitigates some of the change in center to center distance, so a pair of fixed studs can be used across a few amperage ranges if the stud diameter is small enough. The electrical contact is made by the clamping surfaces, so any looseness with respect to the fit of the stud is inconsequential as long as the correct nuts and washers are used and tightened properly.

This is the answer to the question that you said you had trouble figuring out. (((Yes, Class T fuse dimensions change at different amperage levels.)))

Please don't hang the fuse off the terminal unsupported. That is a terrible idea... no mechanical support, no electrical insulation, etc, etc.

I would never do that..... as indicated in the following post. (But why do people seem to think this is ok?)

There is very little in electrical equipment that is fully dummy proof. Nothing except knowledge would stop you from putting a 400 A fuse into that block, and using #6 wire, which is not properly protected by that fuse.

I know this. It took me a while to absorb that the fuse is not rated for the just for the pull, it is for the wire limitations as well. Am I correct on this - please feel free to beat me don and push me to the corner on this one?

This forum has its share of solar installers, DIY types, professionals in electrical and engineering fields who are hobbyists but able to contribute their knowledge. This is not a forum like HVAC-Talk or Mike Holt, owned and operated by industry professionals for the benefit of professionals, so please don't expect the same kind of technical vetting. Especially on topics of safety, you'll find a lot of caution in the responses, because no one wants you to misunderstand or misapply advice that is given and find yourself in a bad way. There is a basic level of electrical awareness and safety practice that must be understood before you get too far into your solar project, and if your questions or comments demonstrate too much ignorance of that, it isn't reasonable to expect this community to fix that for you.

I never expected professional help, I was hoping someone (solar installers, DIY types, professionals in electrical and engineering fields) that actually had hands on experience would be able to lay it down ao that myself an others could benefit. If viewers are here to help and do not understand, I would assume they would ask for clarification vs becoming shy and avoiding the topic. I have seen a few on here that have the knowledge and skill (CME) and have no issues throwing out information.

I feel that my question is legitimate and does not indicate that I am ignorant of electrical requirements, but others out there in the same boat may be. It would probably be good for them to know that just because you can fit a 6AWG wire into a 400AMP fuse block doesn't mean you should.

So now I feel like I have posed a serious question that could easily be answered and instead have been referred to the the corner of the room with a dunce cap.
As a Mod, I think you would stop and think about the traffic of people that come here for information - most of my base knowledge comes form this particular forum. I do not think I am the only one out there that would like to know if different Class-T Fuses could be used on that solar inverter fuse block. (Yes, I know. Battery fusing is serious, this is why I am here)
I ordered a smaller amperage one and will report back

Littelfuse_Fuse_JLLN_JLLS_Datasheet.pdf

[sensij]

I ordered a smaller amperage one and will report back

Dimension F on the fuse data sheet tells you the size of the hole. For the 70-100 A class, the hole is 0.281".

The Go Power data sheet for the fuse block indicates 5/16" fastenings (0.312").

From this, I'd say that when the data sheet says it is compatible with 110-400 A fuses, it will in fact only work with fuses in that range, and the smaller fuses won't fit.

I will write more later to help explain the recommended fuse size table you included in your last post.

[DrLumen]

To your concerns about using the wrong fuse in the same block, it is possible to stick a fuse in that has a higher capacity than what you need or should use. I know you are thinking it should not be possible but if you look around you will see it in many places. The fuse block in your car allows blade or glass fuses that range from fractions of an amp to 20+ amps. In the case of a specific range, the blade fuses only external difference is the color of the fuse or the amp rating engraved on the end of the glass fuse. The old screw in type fuse boxes used in homes would take anywhere from 15 to 50 amp screw in fuses - they all screwed in the same way. Yes, you could screw a 50 amp fuse in the socket where there should be a 15 amp fuse. Some people would even jam pennies in to short around the fuse. Should you? No!

The fuse is primarily intended to protect the wiring. Secondarily, it will help protect the gear some but it is usually the gear (load) that causes the over current condition. In the event of a dead short in the wiring, hopefully the fuse will protect your gear by blowing quickly.

Ultimately, it up to your electrician (or you) to determine what the load is (amps needed) and to install the correct fuses.

[Gdwats]

First lesson, Don't get parts at automotive stores. They are generally cheap, and if you get a 30A fuse & holder, it starts melting at 20amps. They just are not well made. Maybe parts from a auto stereo store would be ok, those are often heavier duty and may last, Parts from Marine Supply centers are usually very well built and hold up,

Fuses are to protect the wires from bursting into flame, if a problem in the wire develops. Circuit breakers protect like fuses, and many are able to function as a switch to turn circuits off and on.. For Solar, there are special DC circuit breakers, standard household AC breakers will not reliably work on DC.

Good to know. Do you have any leads whete to get these in the U.S.? I could at least look at a model and read the manual to better know which/where/how to install on my 4x225 Trojans
I'll be pulling just 1500W at 24V, with some surges no doubt. Inverter can handle 3000W surge.

[SunEagle]

Good to know. Do you have any leads whete to get these in the U.S.? I could at least look at a model and read the manual to better know which/where/how to install on my 4x225 Trojans
I'll be pulling just 1500W at 24V, with some surges no doubt. Inverter can handle 3000W surge.

If you are looking at fuse blocks with a high amp rating I would recommend the Blue Sea type.

[liteyear98]

Good to know. Do you have any leads whete to get these in the U.S.? I could at least look at a model and read the manual to better know which/where/how to install on my 4x225 Trojans
I'll be pulling just 1500W at 24V, with some surges no doubt. Inverter can handle 3000W surge.

You can get the smaller (Boat type - this to me, is auto) DC circuit breakers in lower amperages (60 /100 from what I have seen) online (ebay / amazon) but they are limited in capacity.

Caliber.jpg




















You can get bigger DC Breakers, but they require a box. I am not sure how close you can get to the battery with these, but it isn't right at the terminal like the Blue Seas fuse blocks (MRBF)

Midnite video on DC fuses

[liteyear98]

If you are looking at fuse blocks with a high amp rating I would recommend the Blue Sea type.

Sun Eagle - Thanks, I have seen these and they seem good for smaller applications.

I liked the one in OP because it did not require a ring terminal - just cut, peel, insert and torque. It seemed like it was more durable and would provide less resistance.

I just want sure how those would hold up with a heavy cable occasionally putting stress on them

[liteyear98]

To your concerns about using the wrong fuse in the same block, it is possible to stick a fuse in that has a higher capacity than what you need or should use. I know you are thinking it should not be possible but if you look around you will see it in many places. The fuse block in your car allows blade or glass fuses that range from fractions of an amp to 20+ amps. In the case of a specific range, the blade fuses only external difference is the color of the fuse or the amp rating engraved on the end of the glass fuse. The old screw in type fuse boxes used in homes would take anywhere from 15 to 50 amp screw in fuses - they all screwed in the same way. Yes, you could screw a 50 amp fuse in the socket where there should be a 15 amp fuse. Some people would even jam pennies in to short around the fuse. Should you? No!

The fuse is primarily intended to protect the wiring. Secondarily, it will help protect the gear some but it is usually the gear (load) that causes the over current condition. In the event of a dead short in the wiring, hopefully the fuse will protect your gear by blowing quickly.

Ultimately, it up to your electrician (or you) to determine what the load is (amps needed) and to install the correct fuses.

This post IS the best answer......

The fuse block in your car allows blade or glass fuses that range from fractions of an amp to 20+ amps. In the case of a specific range, the blade fuses only external difference is the color of the fuse or the amp rating engraved on the end of the glass fuse.
This makes the most sense - So you need to know what circuit requires based on wire capability and current draw to determine the correct fuse for the job.
It also helps me understand that you can use different fuses even though they may not be the right dimensions or amperage.
Thank You!