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Fuse Ratings
Tiger Super Six - 31/1/06 at 09:30 AM

Can anyone help - when I built my car the fuse box had no fuses in it. I have put fuses in but am not sure if I have got the correct one in.

How do I check the relevant rating for each of the fuses to ensure that they are correct? I don't know much about electrics so please advise as if I am a numpty.

Cheers in advance,

Mark.

DarrenW - 31/1/06 at 09:48 AM

Which loom is it. Im sure the PW loom has the ratings in the instruction sheets.
If Tiger loom they should be able to tell you.

Tiger Super Six - 31/1/06 at 09:53 AM

It is the Tiger loom but the problem is that the wires are now up and under the scuttle so cant be seen.

I assume that there must be a way of testing them when in situe?

Mark.

theconrodkid - 31/1/06 at 10:01 AM

if you know what loads go through each fuse,work out the current draw and add 50%

ReMan - 31/1/06 at 10:22 AM

quote:
Originally posted by theconrodkid
if you know what loads go through each fuse,work out the current draw and add 50%


....by dividing the Watts, by 12.

eg 2x 65 watt headlamp bulbs = 130 watts.

divide by 12 = 10.83 Amps

Use next standard size up = 15 amp fuse.

smart51 - 31/1/06 at 10:35 AM

12V is your battery idle voltage. Your alternator is probably going to give a value of 13.8V on average.

Anything with a motor will draw a large current to start which will then drop to a steady value. Your fuse should count for the surge. I blew a couple on my rad fan. The next size up cured it.

ReMan - 31/1/06 at 10:44 AM

quote:
Originally posted by smart51
12V is your battery idle voltage. Your alternator is probably going to give a value of 13.8V on average.


....by dividing the Watts, by 12.

eg 2x 65 watt headlamp bulbs = 130 watts.

divide by 13.8 = 9.42 Amps

add 50% = 15 amp fuse.



(More volts is less amps!)

[Edited on 31/1/06 by ReMan]

Tiger Super Six - 31/1/06 at 11:11 AM

Cheers for the above replies - is there a way to find out the draw going across each fuse?

I don't know the circuits as I can only see the front of the fuse box?

Is it possible to put a contact to earth and then the positive on the fuse to see the draw??

Mark

dave1888 - 31/1/06 at 12:44 PM

do you have a 6-fuse or 12-fuse loom.

silex - 31/1/06 at 12:57 PM

Take out a fuse and put an ammeter between the fuse box terminals to measure the current that would pass through.

As you do not know exactly what circuit is connected to which fuse, turn everything on in your car. You will have to do this for each fuse in turn, but at least you will get direct measurements of the current draw.

DaveFJ - 31/1/06 at 01:23 PM

If you have the 6 fuse loom I can take a piccy of mine tonight so you can see th fuse locations.......

theconrodkid - 31/1/06 at 01:41 PM

or if you havnt got an ammeter,remove a fuse,see what dosnt work,mainly light i suspect,count the wattage of bulbs on that circuit,devide by the number you first thought of and job done
if only women were as simple as electics

[Edited on 31/1/06 by theconrodkid]

Tiger Super Six - 31/1/06 at 03:05 PM

quote:
Originally posted by dave1888
do you have a 6-fuse or 12-fuse loom.


I have got the 12 fuse loom.

Cheers,

Mark.

Tiger Super Six - 31/1/06 at 03:07 PM

quote:
Originally posted by silex
Take out a fuse and put an ammeter between the fuse box terminals to measure the current that would pass through.


This seems the simple way - will it work though or would the circuit not work while there is no fuse in it??

or does the volt meter work as connection across the terminals and therefore connection would be made, the volts would be known and the circuit would effectivly work??

Cheers for the help guys.

Mark

iank - 31/1/06 at 03:25 PM

quote:
Originally posted by Tiger Super Six
quote:
Originally posted by silex
Take out a fuse and put an ammeter between the fuse box terminals to measure the current that would pass through.


This seems the simple way - will it work though or would the circuit not work while there is no fuse in it??

or does the volt meter work as connection across the terminals and therefore connection would be made, the volts would be known and the circuit would effectivly work??

Cheers for the help guys.

Mark


The ammeter in place of the fuse will allow the circuits to work.

Another simple, if wasteful way, is to start with a small fuse turn stuff on till it blows, turn off, put in the next size up repeat until it stops blowing.

emsfactory - 31/1/06 at 06:30 PM

Just weld big nails across all the contacts.

Tiger Super Six - 1/2/06 at 09:24 AM

quote:
Originally posted by emsfactory
Just weld big nails across all the contacts.


What an excellent and helpful piece of advice - cheers.

Mark

02GF74 - 1/2/06 at 10:05 AM

quote:
Originally posted by Tiger Super Six
quote:
Originally posted by emsfactory
Just weld big nails across all the contacts.


What an excellent and helpful piece of advice - cheers.

Mark


you woyuld be better using copper or the series land rover approach, all fuses 35 A!

If you drive a modern car, then take a peak inside the fuse box; on the cover is a list of the circuits and you can see what uses what size fuse.

emsfactory - 2/2/06 at 12:14 AM

quote:
Originally posted by Tiger Super Six
quote:
Originally posted by emsfactory
Just weld big nails across all the contacts.


What an excellent and helpful piece of advice - cheers.

Mark


Woohooooooooo. Touchy.

RazMan - 3/2/06 at 11:29 PM

As a very rough guide, all circuits will be more than likely be 10 Amps except headlights (20A) and main fuse (40A)

Obviously this is just a guide but it might give you a good idea where to start.

Bob C - 4/2/06 at 04:01 PM

most meters these days only have a max 10A DC current scale & this is typically fused so have a care - you need to know the result before you dare try to measure it!
Remember the fuses are there to prevent loom fires - it makes sense to use the highest ampage fuse that will protect the associated wiring.
Note also that light bulbs take much higher current on startup too (because the filament resistance is much less when cold) but this surge is generally shorter than the thermal time constant of a normal fuse anyway!
Bob