Ampere Interrupt Capacity (AIC) fuses selection

DIY
1

Ampere Interrupt Capacity (AIC) fuses selection.

Ciao a tutti, I need some information.

According to ABYC standards, fuses must have a minimum AIC that depends on the total CCA of the batteries. They also distinguish between the “DC MAIN” (I assume the cable that connects the batteries) and the “DC BRANCH” connections (I assume all the others). I have two house batteries, each with 700 CCA, therefore a total of 1400 CCA. Consequently, according to the “Interrupt Rating Table”, I would need at least 5000 AIC for the DC MAIN (I chose an ANL fuse with AIC 6000) and 2500 AIC for the DC BRANCH. For the latter, I would have to protect the cables of an MPPT 100/30, an IP22-30A battery charger and an Orion xs 50A.

Which fuses do you recommend? ? Are these values about AIC corrects ? Mega fuses 2000 ? MIDI fuses 5000 ?

Victron often indicates mega fuses.

Thanks for the answers.

2

You didn’t indicate if they were house batteries, starting batteries, or both or what voltage so I’ll assume 12V house batteries. For a 12V system, you could use MRBF fuses at the battery terminals since they have an AIC of 10kA at 14V. Better yet would be Class T fuses with an AIC of 20kA up to 125VDC.

3

Thanks for the answer.

12 volts house batteries.
My doubt was whether to choose MEGA or MIDI fuses for the Victron products indicated in the post.

4

Oh, now I understand. If you use one of the fuse types I mentioned above for your batteries, then either MEGA or MIDI fuses for the Victron components is just fine.

5

Thanks again.

6

@skuner have you seen this post? Fuses and Wattloss on T Class MEGA EF3 and DC Breakers - #9 by HRTKD

Ignore the bit about “#9 by…” That’s just my software being funny.

What is CCA for my own education?

@OGPS I have read that when it comes to fuses, it is not just about AIC but also speed.

My understanding is that you are safe with Class T fuses.

7

Thanks for the answer.

CCA = Cold Cranking Amperes about a battery.