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Class T and MEGA fuse/holder brand recommendations...

fisherman

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May 3, 2022
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NW Ontario Canada
Good Morning,

I need a Class T holder/fuse for my Battery to Inverter setup. What brands/models would be recommended?

Also I need MEGA fuses for the Lynx Distributor. Also looking for brand recommendations for these.

Thank you in advance!
 
I got my class T from shunts.com - best price at the time I found that was in stock and the fuses that they shipped were Littelfuse, so good stuff. I was surprised how cheap they were compared to other places at the time, especially given the supply issues. This was a couple months ago.
 
OP since you mention a 48 volt multiplus in a previous post I expect you want mega fuses rated for 58 volts.
Most mega fuses are only rated to 32 volts.
Caveat emptor.
 
eaton/bussman littlefuse and mersen all make class t fuse holders.
I went with the bussman myself. good luck a lot of places were sold out or month delay or way overpriced in current situation.
Maybe it's changed in the last 3 weeks?
Make sure your class t fuse is DC rated, they sell ac rated ones only as well.
 
I've been having a lot of trouble finding Class T fuses until someone mentioned Homedepot had them in stock.. I see they have 1 200A left and some other amperages without the fuse holder.

It seems it is very difficult finding the bolt on class.T fuse holders for some reason.

You can easily find the MEGA fuses.. even the Victron labelled ones on places like solar-electric.com

And just as a FYI since I had trouble determining the reason for why you would use a MEGA fuse in some places and a T fuse in others is that the MEGA fuses typically have 1/10th the current interrupting capability of a T fuse but are usually a lot cheaper.
 
OP since you mention a 48 volt multiplus in a previous post I expect you want mega fuses rated for 58 volts.
Most mega fuses are only rated to 32 volts.
Caveat emptor.
48V is out since the inverter I wanted isn't UL.
And just as a FYI since I had trouble determining the reason for why you would use a MEGA fuse in some places and a T fuse in others is that the MEGA fuses typically have 1/10th the current interrupting capability of a T fuse but are usually a lot cheaper.

Exactly it came recommended as the Lynx distributor only uses MEGA and it'd be good to have a T fuse between that and the battery
 
48V is out since the inverter I wanted isn't UL.
Here is another option with very similar transfer schema.
 
Good Morning,

I need a Class T holder/fuse for my Battery to Inverter setup. What brands/models would be recommended?

Also I need MEGA fuses for the Lynx Distributor. Also looking for brand recommendations for these.

Thank you in advance!

Here is a good link for T-Fuse


I prefer the MRBF Terminal Fuse to the MEGA assuming the system uses Lifepo4 batteries. The MRBF Terminal Fuse has a much higher interrupt capacity.


Here is what I used. maybe will work for your system...



 
Here is another option with very similar transfer schema.
Wow that is nice. Will have a look at those if I go 48v

Here is a good link for T-Fuse
Thanks I will check those out!
 
Here is a good link for T-Fuse


I prefer the MRBF Terminal Fuse to the MEGA assuming the system uses Lifepo4 batteries. The MRBF Terminal Fuse has a much higher interrupt capacity.


Here is what I used. maybe will work for your system...



Man, I have been searching all day for a Class T fuse IN STOCK. I found a 350Amp one in stock. Mind if I ask a question? SS tech guy said I should get a 400A T fuse. Will used a 300A T fuse. I figured I needed a 312A so, wondered if the 350A T fuse is too close to that number and the 400A T Fuse would be better? I am stuck on this one item. I want it to go between the Growatt(48V)12KW 250V 120A off-grid inverter and the EGLL 48V 5.12kw batteries (times 6) that I bought from SS. Probably using the wrong conversion and all.
 
Man, I have been searching all day for a Class T fuse IN STOCK. I found a 350Amp one in stock. Mind if I ask a question? SS tech guy said I should get a 400A T fuse. Will used a 300A T fuse. I figured I needed a 312A so, wondered if the 350A T fuse is too close to that number and the 400A T Fuse would be better? I am stuck on this one item. I want it to go between the Growatt(48V)12KW 250V 120A off-grid inverter and the EGLL 48V 5.12kw batteries (times 6) that I bought from SS. Probably using the wrong conversion and all.

The main factor to consider when sizing a fuse is the battery cables you are using. The cables have the capability to handle specific amounts of amperage, based on their gauge. If there is a short, and a greater amount of amperage is allowed to pass, the wire could melt or catch fire before an oversized fuse blows to interrupt the circuit.

To properly determine fuse size we need to consult NEC table 310.17 for wire in free air, see attached PDF.

Example: according to the table a #3/0 AWG copper wire with 90°c insulation is rated for 350 amps. So for this example a 350 amp T-fuse is sufficient.

Note: this only applies to running battery cables with 90 degree insulation in free air and not running the cable(s) through a raceway or conduit.

For the Inverter 12000w / 0.85 (efficiency of Inv) / 48V * 1.25 (fuse multiplier) = 367Amps.
So for the Inverter a 350 amp T fuse should work.

So with 3/0 90 degree wire with a 12KW inverter the 350 amp T fuse looks like a good choice. If you find the inverter has significant large surges from the loads and the 350 blows then the 400 may be the better choice, but if the 350 blows the loads maybe overloading the inverter.

I personally prefer to have the fuse a little on the lower side so my choice would be a 350 amp T fuse.

I don't know what gauge wire Will is using. Possibly less than #3/0 AWG so a lower amp fuse is used to match the wire between the battery and inverter.
 

Attachments

  • FREE AIR—ALLOWABLE AMPACITIES OF CONDUCTORS.pdf
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The Growatt 12000 250v 120a all-in-one suggests 3*2awg but I have not ever seen anyone run 3 different wires for the same run. I am so new at this, that I am regretting even trying. I have researched and researched and I don't want to burn anything down but so much conflicting info out there. Some people are saying 4/0 would be better than what the Growatt manual says. At this point, I am about to give up. I have read all of your responses and I know you know your stuff, so I appreciate you taking the time to help. I really do. My batteries will be less than 3 feet away from the growatt in the rack. I thought with 48V the wires could be smaller.
 
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