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Class T Fuse Sizing

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PerryB67

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This morning I went down to the camper to install the 200a Class T fuse and it doesn't fit. Turns out there are at two sizes of Class T fuse holders. The smaller is up to 200a and the larger is for => 225a. I have a 200a Blue Sea fuse but a 225-400a Blue Sea fuse holder. The inverter recommends a 250a fuse, but since they're almost impossible to find I purchased a 200a. Our toaster at 750 watts is the largest device currently on the circuit, but you never know what we'll add.

Tried to find the smaller 35-200a fuse block but have had no luck so far. According to the Blue Sea website they don't make one.

I either have to find the smaller fuse block or a 225-250a fuse for the larger fuse block.

Anyone have luck finding either?
 
search Class T on Amazon.
But I didn't notice the different detentions. Guess I got lucky when I purchased my fuses.
The Blue Sea part number for the smaller fuse block is; 5007100. These are a new size fuse (to Blue Sea) introduced after I had bought mine.
 
Last edited:
PerryB67 said:
This morning I went down to the camper to install the 200a Class T fuse and it doesn't fit. Turns out there are at two sizes of Class T fuse holders. The smaller is up to 200a and the larger is for => 225a. I have a 200a Blue Sea fuse but a 225-400a Blue Sea fuse holder. The inverter recommends a 250a fuse, but since they're almost impossible to find I purchased a 200a. Our toaster at 750 watts is the largest device currently on the circuit, but you never know what we'll add.

Tried to find the smaller 35-200a fuse block but have had no luck so far. According to the Blue Sea website they don't make one.

I either have to find the smaller fuse block or a 225-250a fuse for the larger fuse block.

Anyone have luck finding either?
Click to expand...
There's a lot more than two sizes of class T lol.

I think there's actually 6 or more, and the corresponding fuse geometry changes.

I did the same mistake as you on the first one and... made the fuse fit. However I will say that's largely a really bad idea for a safety device and you shouldn't follow my example.

Not sure where you're looking for parts but they are fairly easily found online at various retailers. Automation Direct has a huge selection of them BUT they're very expensive. Don't limit yourself to common RV/marine retailers as we use them a lot in industrial applications.
 
An easy work-around is to use the smaller holder and wire two 100A fuses in parallel to give 200A

12V at 750W is 62A. You could wire two sockets in parallel, but only fit one 100A fuse until you add more load.
 
Since my original post I sent back the smaller Class T fuse holder and have installed a larger holder with a 250a Class T fuse purchased from West Marine for $52 plus tax and my drive to their store. I since have purchased two backup fuses (which Murphy say's I'll never need) from Best Converter for $30 each plus $7 shipping.

I found the 250a fuse extremely hard to find

Enjoy,

Perry
 
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