question

sasunnu avatar image
sasunnu asked

Multiplus-II Wire Size Smaller Than Fuse?

I've purchased a Multiplus-II 24/3000/70, and the manual recommends a 300A fuse, but then only 50mm2 wire size - am I correct in thinking this would be undersized for a fuse of this size?

I'm also wondering if anyone has used a smaller fuse of say 175-200A?

Multiplus-IIfuses
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1 Answer
kevgermany avatar image
kevgermany answered ·

I'd stick with the recommended size. The start current on the multiplus can be very high as its capacitors charge. If you do get a short, a 300A fuse will blow quickly.

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sasunnu avatar image sasunnu commented ·
Thanks. The 50mm 2 wire would be undersized for a 300A fuse though, wouldn't it?
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kevgermany avatar image kevgermany ♦♦ sasunnu commented ·
Guess it depends how you're using things. Here not.
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sasunnu avatar image sasunnu kevgermany ♦♦ commented ·

Sorry if my questions are dumb, I'm quite new to this. Do you mean if I am not running the multi to full capacity then 50mm2 would be sufficient? The 50mm2 cables I am looking at have an amp rating of 246 at 30oC, and in all the wire size/maximum amperage charts I have seen 50mm2 is always under 300A.

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munga avatar image munga sasunnu commented ·

On a good day the MP2 will only draw ~150A (continuous) to make its 3000W so your 50mm2 cable is safe. The fuse rating is, as @kevgermany points out, to deal with high start up currents of the MP2 etc. If you have a short circuit, this will exceed 300A very quickly and the fuse will blow (very quickly) and your cables will also be safe.

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kevgermany avatar image kevgermany ♦♦ sasunnu commented ·
@munga said it for me, thanks.

But no dumb questions, we all had to learn. So ask away.


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