# What size fuse.



## Neckender (Feb 18, 2010)

As You all know I've recently installed a 100watt solar panel with 10 amp controller, what size fuse would you recomend down at the battery end, 15amp, 20 amp or any other size. 

Thanks for yor help.

John.


----------



## shortcircuit (Feb 18, 2010)

The size of the fuse must be less than the current rating of the cable you have used.


----------



## biggirafe (Feb 18, 2010)

trikerman said:


> As You all know I've recently installed a 100watt solar panel with 10 amp controller, what size fuse would you recomend down at the battery end, 15amp, 20 amp or any other size.
> 
> Thanks for yor help.
> 
> John.



I think this is right 
Amps = Watts / volts so theoretically your panel can provide 8.3 amps. a 10amp fuse should do the job.


----------



## shortcircuit (Feb 18, 2010)

biggirafe said:


> I think this is right
> Amps = Watts / volts so theoretically your panel can provide 8.3 amps. a 10amp fuse should do the job.



And if the cable used is rated at 5amps you have a fire!


----------



## biggirafe (Feb 18, 2010)

shortcircuit said:


> And if the cable used is rated at 5amps you have a fire!



Correct but that was not the question


----------



## shortcircuit (Feb 18, 2010)

biggirafe said:


> Correct but that was not the question



I dont see how.  The fuse is there to protect the cable and if you do not no the size of cable then you cannot suggest a size.


----------



## biggirafe (Feb 18, 2010)

shortcircuit said:


> I dont see how.  The fuse is there to protect the cable and if you do not no the size of cable then you cannot suggest a size.



One would hope that he has read your first post about the cable and has the correct cable for his panel , But regardless if he fits a fuse lower than the panel is going to supply it will blow anyway. Chicken and Egg the 2 go together IMHO and both should be suggested together.


----------



## shortcircuit (Feb 18, 2010)

biggirafe said:


> One would hope that he has read your first post about the cable and has the correct cable for his panel , But regardless if he fits a fuse lower than the panel is going to supply it will blow anyway. Chicken and Egg the 2 go together IMHO and both should be suggested together.




And what about the power the battery will supply back up the cable in the event of a fault in cable?


----------



## biggirafe (Feb 18, 2010)

shortcircuit said:


> And what about the power the battery will supply back up the cable in the event of a fault in cable?



But 10 amp is still the smallest fuse you can fit (well 8.33 but they don't make those). Hense having the fuse at the battery end but you know this.....


----------



## shortcircuit (Feb 18, 2010)

biggirafe said:


> But 10 amp is still the smallest fuse you can fit (well 8.33 but they don't make those). Hense having the fuse at the battery end but you know this.....




Assuming they are spade fuses

Box of Car Spade Fuses

Set of 80 fuses for automotive use.

Contents

    * 10 x 3A  Fuses
    * 10 x 5A  Fuses
    * 10 x 7.5A  Fuses
    * 10 x 10A  Fuses
    * 10 x 15A  Fuses
    * 10 x 20A  Fuses
    * 10 x 25A  Fuses
    * 10 x 30A  Fuses
    * 1 x Tool


The fuse must be less than the rating of the cable and not just what is available


----------



## biggirafe (Feb 18, 2010)

shortcircuit said:


> Assuming they are spade fuses
> 
> Box of Car Spade Fuses
> 
> ...



No one is disagreeing with you, but the fuse must also be large enough to cope with the current produced by the solar panel. Its not a radio or similar that is just going to 'suck' power it is also going to produce power (if the sun ever shines).

If his solarpanel *produces* 8.3 amps then the fuse MUST be bigger than this even your list above shows that 10amps is the smallest vehicle fuse he can use.

But I'm bored with this if you don't get it now you never will


----------



## shortcircuit (Feb 18, 2010)

biggirafe said:


> No one is disagreeing with you, but the fuse must also be large enough to cope with the current produced by the solar panel. Its not a radio or similar that is just going to 'suck' power it is also going to produce power (if the sun ever shines).
> 
> If his solarpanel *produces* 8.3 amps then the fuse MUST be bigger than this even your list above shows that 10amps is the smallest vehicle fuse he can use.
> 
> But I'm bored with this if you don't get it now you never will



Unfortunately its not boredom but failure to comprehend.  

If the cable has to deal with whatever output from the solar panel it must have a rating to carry the current supplied.  At the battery the fuse must be rated to be below the rating of the cable but above that of the anticipated output of the panel otherwise you risk serious consequences in the event of cable faults it will "suck power" from the battery, big style.

I trust you now comprehend


----------



## coolasluck (Feb 18, 2010)

How about a fight you two,you could both be the undercard to an aj ,channa main event!!


----------



## Neckender (Feb 18, 2010)

Thanks Biggiraf, and shortcircuit, I have used the proper cable the same as comes with solar panel, so I will fit a 10 amp fuse. The reason I've asked the original question is a mate of mine is a auto electrician and he supplied and fitted fuse holder only, and he has fitted a 30amp spade fuse which I considered was to big. so thanks again guy's, didn't mean for you to fall out though.

John.


----------



## shortcircuit (Feb 18, 2010)

trikerman said:


> Thanks Biggiraf, and shortcircuit, I have used the proper cable the same as comes with solar panel, so I will fit a 10 amp fuse. The reason I've asked the original question is a mate of mine is a auto electrician and he supplied and fitted fuse holder only, and he has fitted a 30amp spade fuse which I considered was to big. so thanks again guy's, didn't mean for you to fall out though.
> 
> John.




I am glad its been of use to you although a bit long winded.  My logic was to explain why, rather than blindly fit an incorrect fuse.

Life is to short to fall out about minor issues


----------



## bevdrew (Feb 19, 2010)

I may be missing something here, but why do you need a fuse at the battery end? 

bev


----------



## AndyC (Feb 19, 2010)

bevdrew said:


> I may be missing something here, but why do you need a fuse at the battery end?
> 
> bev


To prevent a fire due to overheating of the cable in the event of a short circuit.

AndyC


----------



## n8rbos (Feb 19, 2010)

trikerman said:


> Thanks Biggiraf, and shortcircuit, I have used the proper cable the same as comes with solar panel, so I will fit a 10 amp fuse. The reason I've asked the original question is a mate of mine is a auto electrician and he supplied and fitted fuse holder only, and he has fitted a 30amp spade fuse which I considered was to big. so thanks again guy's, didn't mean for you to fall out though.
> 
> John.



if your m8 is an auto-electrician then surely its his job to know what size fuse is adequate! so y did he fit a 30amp?


----------



## shortcircuit (Feb 19, 2010)

The auto elec should have checked but it may well be like the 13 amp plugtops that all come with 13a fuse and you are supposed to fit to suit appliance and how often does that happen?


----------



## coolasluck (Feb 19, 2010)

But is there going to be a fight,thats what is important,we are all wanting to know?


----------



## shortcircuit (Feb 19, 2010)

coolasluck said:


> But is there going to be a fight,thats what is important,we are all wanting to know?




I need directions to "Sunny Torbay"

There may well be a fight and you will not be holding the jackets!

Ill be down when the sun shines


----------



## coolasluck (Feb 19, 2010)

shortcircuit said:


> I need directions to "Sunny Torbay"
> 
> There may well be a fight and you will not be holding the jackets!
> 
> Ill be down when the sun shines






Come on then if you think yer hard enoughthink you can handle the fantastic hot sun down this end of the country and if you can,well you will have to try and catch me in a foot race first,and if you can well.......ive got mates


----------



## shortcircuit (Feb 19, 2010)

coolasluck said:


> Come on then if you think yer hard enoughthink you can handle the fantastic hot sun down this end of the country and if you can,well you will have to try and catch me in a foot race first,and if you can well.......ive got mates



The words of a troubled man.  Nice banter!


----------



## runnach (Feb 19, 2010)

fisticuffs are a definate no no boys !!!....especially if you have an allergy to pain 

I went to the dentists yesterday, and had me knoshas sorted out, so hopefully the looming trip doesnt require a visit to the dentists.

I was in the chair an hour and a half !!!!.....I want my dentist as my cornerman !!....flippin eck that lignocaine they inject you wiv you cant feel a thing...ideal if you meet Frank Bruno on a dark night 
Channa


----------



## cipro (Feb 19, 2010)

You have a big smile then once your lips become normal  you normally
can't drink proppplllyyy for a while................


----------

