Midi Link Fuses Versus Mega Link Fuses

[alan_fincher]

I can probably research this myself in more detail, but am hoping someone can provide a quick answer......

 

When redoing some 12 volt electrics on "Flamingo" I need to introduce some fuses at around a 50 amp rating.

I have used the size before now that I think are generally called Midi Link Fuses, but they have the disadvantage that the holders I bought with them really do not have the capacity to match the crimped terminals I am using on the fairly substantial cables involved (typically 25mm).  The bolts are really too small diameter, as are the ends of the cover.

The simple answer appears to be to switch to Mega Link Fuses, which have bigger bolts and allow for fatter cables.

However Midi fuses typically seem to cover the range around 30A to 150A, whereas most Mega fuses start at 100A and run up to 500A, or so.

So what's the best solution if you want (say) only 50A fuses, but chunky cables which mean you will also have chunky connectors?



 

[DHutch]

Ofcause one question is, why are you using 25mm^2 cable for a circuit only rated at 50amps. I've not done the sums but even on narrowboat lengths the feels overkill.

 

The next thing on the subject is, if to achieve low voltage drops, why not fuse it at 100A anyway and your on standard off the shelf fuses and holders that suit the cable. Unless your planning to have unfused branches of a smaller gauge I see little downsides to this. 

 

Daniel

[PaulD]

8 minutes ago, alan_fincher said:

I can probably research this myself in more detail, but am hoping someone can provide a quick answer......

 

When redoing some 12 volt electrics on "Flamingo" I need to introduce some fuses at around a 50 amp rating.

I have used the size before now that I think are generally called Midi Link Fuses, but they have the disadvantage that the holders I bought with them really do not have the capacity to match the crimped terminals I am using on the fairly substantial cables involved (typically 25mm).  The bolts are really too small diameter, as are the ends of the cover.

The simple answer appears to be to switch to Mega Link Fuses, which have bigger bolts and allow for fatter cables.

However Midi fuses typically seem to cover the range around 30A to 150A, whereas most Mega fuses start at 100A and run up to 500A, or so.

So what's the best solution if you want (say) only 50A fuses, but chunky cables which mean you will also have chunky connectors?



 

I used "forklift" fuses for main fuses. Lots of fuse holders àvailable at reasonable cost or you can bolt them onto busbars with 6mm bolts. Smallest I used was 63A but there is a huge range on the market. Much cheaper than Midi and Mega stuff.

[jonathanA]

I think you can get 50 or 60A mega fuses I was looking for some fuses for my charger and needed a couple I found some mega fuse holders that clipped together side by side making a neat install. 

 

Iirc I wanted 50A fuses so must have found some

 

 

[matty40s]

I tend to use midi fuses on solar arrays rather than mini blade fuses to future protect installations or to allow for change from parallel to series for example. 

I have several good crimpers of various designs if you wish to borrow them Alan.

[WotEver]

1 hour ago, alan_fincher said:

So what's the best solution if you want (say) only 50A fuses, but chunky cables which mean you will also have chunky connectors?

As the fuse is there to protect the cable, why not use a 100A fuse? 25mm sq is more than capable of handling 100A

[alan_fincher]

12 hours ago, jonathanA said:

I think you can get 50 or 60A mega fuses I was looking for some fuses for my charger and needed a couple I found some mega fuse holders that clipped together side by side making a neat install. 

 

Iirc I wanted 50A fuses so must have found some

Yes, I'm sure I found a few before, but the several mainstream suppliers I looked at yesterday started at 100A.

[alan_fincher]

11 hours ago, WotEver said:

As the fuse is there to protect the cable, why not use a 100A fuse? 25mm sq is more than capable of handling 100A

Yes a very valid comment of course.   There will certainly be no cable that's not good for 100A before the fuse, and it will ultimately feed a breaker panel where each of the individual beakers will adequately protect the thinner cables that run on from there.

 

It really doesn't matter if the fuse is 50A, (which is higher than any current I'm expecting to actually be flowing), or 100A (which is easily within the capability of the 25mm cabling).

The reason the cabling is that big will purely be to avoid volts drop as much as possible, not because it ever needs to carry 100A (plus).

[WotEver]

1 minute ago, alan_fincher said:

The reason the cabling is that big will purely be to avoid volts drop as much as possible, not because it ever needs to carry 100A (plus).

Understood. But as it’s easily capable of carrying 100A there’s no problem fusing it as such

 

[alan_fincher]

1 minute ago, WotEver said:

Understood. But as it’s easily capable of carrying 100A there’s no problem fusing it as such

 

For the avoidance f misunderstanding I was trying to say I fully agree with you, and that the bigger fuse will of course be fine! ?

I just need to order stuff now, but knowing what temperatures are like in Flamingo's completely uninsulated engine room right now, there's no rush, as I'm not likely to start the installation until temperatures go up!

[Keith M]

Have you also considered using a Maxi Fuse for the lower currents

ANL fuses are supplied as low as 20 amps.

[rjasmith]

Looks like 40A and 60A are available in the Mega fuse range and there are even suppliers on eBay!

 

Richard