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Class T fuse block

2K views 9 replies 5 participants last post by  Maine Sail 
#1 ·
The new 400 amp Class T fuse block arrived for my inverter/charger install. I was surprised to see the battery cables attach to the block by a terminal screw that crushes down on the bare cable strands. For all the effort to make good lug crimps at the battery and I/C, this seems to be a weak link.

Is there a method to insure maximum contact for this connection? The instruction just say to insert the strands and tightening the terminal screw.
 
#2 · (Edited)
The new 400 amp Class T fuse block arrived for my inverter/charger install. I was surprised to see the battery cables attach to the block by a terminal screw that crushes down on the bare cable strands. For all the effort to make good lug crimps at the battery and I/C, this seems to be a weak link.

Is there a method to insure maximum contact for this connection? The instruction just say to insert the strands and tightening the terminal screw.
Unfortunately you did not purchase a quality Class-T fuse block from a reputable vendor, such as the Blue Sea Systems 5502 400A Class-T Fuse Block.

Sadly there is lots of Chinese junk out there masquerading around with a "marine" sticker.. As a buyer you really need to be careful these days. As a DIY I know this becomes very tough because there are far too many shady businesses out there willing to heist your money and give you a crap product in return. Because of this it's becoming more and more common for me to have to turn down a customers request to install "owner sourced" products than it was 10 or even 12 years ago. Your fuse block would have fallen into that category had you called me in to do that install, and then handed that fuse block to me.

When buying marine electrical items it's best to stick with companies known to be producing quality equipment that has been tested and proven in the marine market. Blue Sea Systems is one, and the BEP/Marinco Pro-Installer line is another.

I have seen some of these cheap car-stereo grade fuse blocks physically melt down due to high resistance. Sadly there are also companies calling themselves "marine" vendors who think nothing of slapping their name on sub-par Chinese products that have never been tested for marine use.

Any fuse, anywhere close to that amperage, used with marine wire, should have the wire physically BOLT to the fuse holder with LUGS not just mash the very thin marine stranding into a lump. Sorry for your frustration but the net is a dangerous place these days...:crying

Blue Sea 5052:


You could not pay me to put something this into a tree-fort let alone a boat:
 
#6 · (Edited)
Unfortunately you did not purchase a quality Class-T fuse block from a reputable vendor....
Damn it! You are right, I was duped. I bought it from Defender and just went back to look at the search screen again. I swore I bought a Blue Sea. They sell the Blue Sea fuse block, which comes up first. Right below it are fuse block kits, which simply come bundled with the fuse. I didn't notice the were GoPower kits. My mistake. Too hard to tell on the small screen that the terminals are different. Ironically, the crap version cost a dollar more than buying the Blue Sea block and fuse separately! I feel like strangling someone. Return and Re-order. Thankfully, the spare fuses I bought were BS. Thanks again for the help.

.....Because of this it's becoming more and more common for me to have to turn down a customers request to install "owner sourced" products than it was 10 or even 12 years ago. Your fuse block would have fallen into that category had you called me in to do that install, and then handed that fuse block to me.....
Wish you were nearby to have the opportunity. At least, in this case, it seemed intuitively wrong to me, so I asked the question.
 
#3 ·
The one with the hex key grub screws is only good for solid conductor, not stranded.
Twisting while compressing will shred stranded wire.

Assuming the metal they used to make it is actually appropriate for the current they rated it to take...

Combining the need for corrosion resistance with high current capacity means a more expensive block is needed.
 
#5 ·
Smaller, but these pass muster?

Samlex DC-FA-100 Fuse Assembly

Picked up a bunch cheap, thinking one per LFP 12v 4S block, right at the + terminal, be able to treat each as an independent unit.
That is called an MRBF fuse and fuse holder and the product that only goes to 300A, 100A shy of the 400A needed above....

The little MRBF ubes are really not suitable to hang 4/0 wire off of without some serious strain relief. Also they make a dual fuse holder but the total protection is still only a max of 300A combined. I have seen folks install two 300A fuses on a fuse holder only designed to handle 300A. D'oh.....

You need to be careful with that style fuse holder because many of the off-brand suppliers are only offering the 1/4" stud post & not the beefier M8 / 5/16" ring stud. That is a product Blue Sea developed in conjunction with one of their suppliers, and others are now re-branding it too, including Samlex.

In some cases I have even seen them knocked off with no testing certs IP rating or even an amperage rating on the holder itself. The Samlex is the real McCoy as are the Blue Sea Systems MRBF's..
 
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