Fuse keep melting

[Budacco]

very helpful thanks!

[Whiteshadow76]

Hi all, just a nub question is it ok to increase the fuse e.g 7.5 to 15?

[Whiteshadow76]

Do you prefer to blow up the fuse, or blow up the car ? Overloading is one of the primary causes of motorcar fires.

 

Hmm many tks for the info

[Yeobh]

Is 7.5amp an under capacity fuse for the load ? Why increase the protection by 100%.

[Kb27]

Hi all, just a nub question is it ok to increase the fuse e.g 7.5 to 15?

Fuse is to protect the wire.

 

If originally the fuse is 7.5A, that could mean a wire capable of handling up to 12A is used.

Now you increase the fuse to 15A, which means you allow up to 15A to pass through the 12A wire.

What happens to the wire? It will overheat, insulation melt away, expose bare wire and under the right condition, poof goes the car.

 

See those cars on fire ?

 

Most of them are due to electrical faults such as the above.

[Mysportwish]

your issue sound complex :) so who managed to solve your problem?

 

 

 

 

 

 

thanks to all who reply...

 

to re-cap the problem:

 

1 )I got a used car and the rear air-con was not working, dealer sent it to WS to fix before handling the car to me.

2) on the day of getting the car, the rear air con was working at 1st, after a while the rear aircon was gone again.. the front air con is working fine.

2a) also found the the rear brake light & haz light was not working

3) dealer ask me to go to their WS for check again.

 

4)went to the WS 2 days later, WS open the fuse box and found the 1 of the fuse area melt (refer to pic 1)

5) from eye check the fuse dont seem to be blow..

6)from pic 1 u can see that 1 of connector "leg" was disconnect from the holder.. the "leg" was pull out together with the fuse.

 

7)the WS then wanted to remove the whole fuse box and open it up, i think they wanted to re-wiring the internal to another spare fuse connector.

8) but the WS had diffculty opening the fuse box..

9) so the solution by the WS was to extend the fuse connection out; by using 2 wire - 1st wire connect to the 12V input, 2nd wire connect to the original connector using soilder, this shall link to the downstream equipment/device. (refer to pic 2 & 3)

10)The original fuse was rated 30A, the WS use another 30A fuse but of bigger size (compare the melt fuse to the new fuse)

11) after connecting up, the air-con, rear brake & haz light was working again.

 

12)when i ask what is the main cause of this, the WS reply most prob cos by over current.

 

 

my main concern:

 

1) what actually cause the overload? I m very concern in finding the root fault and get it fix to prevent any more overcurrent.

 

2) is this "new" connection/wiring safe? as in term can it withstand the overcurrent shall fault happen again? refer to pic 4, the wire is getting a bit of press due to covering of the cover.. not sure if it will cut and expose the wire.

 

3)is it ok to use a bigger fuse with the same rating?

 

4)if this cause by lose connection at the original fuse connector, can i assume this will like be 1 off type of fault since the current soultion seem secure at the fuse.

 

[Simpleonly]

Issues not really solve... Just rewire it to look nicer n neater instead of flying across... Concept of the other WS that did for me is the same but neater n look more pro.. A big thanks to my good buddy who intro me there..

 

Cheers

[Good-Carbuyer]

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Many thanks. Useful video

[Tornado220]

Let’s be clear, fuses are not and never were added to protect an item !  They are there to protect the wires !!  Anyone who says otherwise has no idea what they are talking about !!!

 

[Tornado220]

On 6/6/2009 at 2:01 PM, Kazuo said:

One of the fuse in my fuse box in the engine bay keep melting.

 

It's the heater, 30amp. Not just the fuse plastic melt, but the plastic surround that particular connector also melting away.

 

However, the fuse doesn't blow, but somehow affect the functionality of my aircon blower.

 

Any idea what's wrong? or what could be the cause?

So look at what can cause the fuse to overheat, it can only be 2 issues, 1 that an external source is overheating the plastic, or 2 that a higher internal resistance is overheating the circuit, so look for incorrect wire sizes causing high resistance and heat or a bad crimp / contact point.

if it’s all standard then look for damaged circuit or other connection point

if it’s modified check the total capacity against wire sizes and crimps used 

bottom line your system is maxxing out and could be dangerous 

fuses protect wires not components 

[Tornado220]

@Good-Carbuyer total rubbish ! Fuses are only meant to protect wiring !  Nobody cares if your £4000 ICE system fails as it won’t cause a fire !

wires get hot you have a thermal event and a slow agonising death in the millisecond it takes before you plough into some road furniture 

[Rayleigh]

2 hours ago, Tornado220 said:

Let’s be clear, fuses are not and never were added to protect an item !  They are there to protect the wires !!  Anyone who says otherwise has no idea what they are talking about !!!

 

In the context of a vehicle, it is correct. In equipments or appliances, that may not be true. For example, one could be using a wire with high rating and the fuse is to prevent incidences such as short circuit at the downstream  

[Tornado220]

@Whiteshadow76 not unless the rest of the system is uprated to cope with the higher current draw, otherwise a fire could start

[Tornado220]

@Rayleigh The name is at the top of the forum ;)