A 50 amp Fuse Question

It was hot today and the A/C stopped working (duh!) whilst stuck in a traffic jam. The 50 amp fuse had blown and it was a new one.

I find it almost impossible in Australia to buy 50 amp glass fuses but located a place on the other side (of course) of the country that had them so I bought a quantity on line.

The issue is, although they are listed as 50 amp and are stamped so on the end they are very thin and look identical to low amp fuses. I despair they will all blow in short order.

The pic shows a 35 amp with a new 50 amper plus the blown one.

Can they still be 50 amp being so thin? Would I be better off using the gutsy looking 35 amper until I get new ones from the UK?

It’s going to be 38c three days in a row so I’d like the A/C working.

Fuses are minefields, Don…:slight_smile:

The top one likely shows a proper quick-blow 50A fuse - the width of the ‘neck’ denotes the current it can pass without overheating and blowing.

Both the material used and the cross section of it decides the resistance and the ‘heat/amp’ capacity, but both are carefully controlled in production, for obvious reasons. While the markings should be consistent; the manufacturers, very unusually, may deviate from standard ‘looks’.

Of more concern is ‘why’ a 50A (fan motors only) blows - it should not do that. Electric motors briefly draws high current at start-up, as they do when stalled, and the fuses are dimensioned accordingly; 50A is ample. So, if your AC stops working due to a blown fuse; you should investigate the reason; you may have short. First check the fuse holder; due to the high fan current, the wires may come loose and short to ground…?

Other markets use ‘slow blow’ fuses, the difference is that ‘quick blow’ fuses blows instantly at the stated amps, while ‘slow-blow’ blows when the current is constantly above rating. 50A ‘quick’ is equivalent protections to a 35A ‘slow’ - which may look different…

You can but try out what you have; a fuse blowing prematurely due to too low rating is vastly preferable to one that holds with excessive current…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

Thanks. The blown fuse is the number 10 fans fuse in the fuse box. The fuses on each side of the tunnel are okay. I replaced the blown with same but that thicker looking 35amp in the pic might be better. I ordered some quick blow 50 ampers from the UK.

It’s supposed to be #16 in the aux fuse panel, Don…?

But the AC fan fuse is the only 50A, so if it ‘fixes’ the problem; your model year may have different numbering - or whatever…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

It’s the same as this one…

I bought these ones from Repco

Seriously? When? I went to repco not long ago and they said they could only get 35 amp. Ill ring em up monday. Thenks for the info.

Edit: just saw them on their website. Thats really annoying but i should have checked i guess.

Nov '23, 20c a pack, I bought 5 :laughing:

I bought all of the fuses on aliexpress:
All good so far. The quality difference is, you can hardly read how strong they are on the fuse itself. I bought a full set for almost nothing.

Fuses are complicated things. In my life with electronic devices that aften included motors we always stuck with the fuses specified in the manuals.

My golden rule is to always order my car’s fuses (haven’t needed any yet except for the electric seats I fitted but now I have a set of spares if I need them) from someone well established and well known dealing in ‘classic car fuses’.

Never order from some wally without a track record, who is probably peddling some Chinese stuff they bought cheap and doesn’t know diddly squat.

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The best fuses are the really old lucas fuses with brass cap and solder.
Then they got really bad.
Chinese fuses have worked okay for me, there is slow and fast blow ratings (50a/35cont.), that’s the important bit.

David, the fuse that blew was the original lucas with the paper inside. It had been there for decades, maybe from new. The only reason it blew was i accidentally shorted it out because i forgot to disconnect the battery.

From Repco? Which store? I went to the local Nov 23 and no 50amp. But they only had Narva.

I think a 35 will do well.

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Bought them online, they came in the post not delivered by a local store.

That sure explains it, Don…:slight_smile:

As David says; a 35A quick blow may be sufficient; there is no risks involved in using lower rated fuses - at worst, they just blow. But fitting higher rated fuses is a no-no whatever the reasoning…:slight_smile:

xj6 85


Shall do. I’ll soon find out if there are other issues at play. At least I’ll know where I’ve been doing other stuff under there so I can retrace steps.

Is there enough clearance in fuse box to accommodate a plug-in Type 2 circuit breaker in lieu of a glass fuse? It seems abnormal to have to keep replacing fuses.

40A Type 2 Circuit Breaker, 40 Amp Auto Reset, Fuse-Clip 3AG AGC SFE, CB120-40 Amazon.com

Do you mean generally? This fuse is nice but a glass fuse will last many years and costs a few cents, I too tend to blow fuses mostly because I‘m too lazy to disconnect the battery…

Im not replacing fuses. One blew because i shorted it. It had been there for decades. The issue seems to be the quality of the replacement that blew after a few weeks.