DIR Return Create A Forum - Home
---------------------------------------------------------
Old Leafsprung Land Rovers
HTML https://ollr.createaforum.com
---------------------------------------------------------
*****************************************************
DIR Return to: Technical tips & Questions
*****************************************************
#Post#: 68419--------------------------------------------------
Fuses
DIR By: ashcrroft752
Date: July 19, 2013, 8:36 am
---------------------------------------------------------
I'm wanting put the correct size fuses into my scratch built
loom, I know I could guess the sizes or copy from a different
vehicle.
I'd like to know how to work out with a multimeter the wattage a
component draws. I should then be able to work out the correct
fuse size.
#Post#: 68421--------------------------------------------------
Re: Fuses
DIR By: Arjan
Date: July 19, 2013, 8:42 am
---------------------------------------------------------
Motors are rated either in Watts or Amps, and by Voltage. If the
motor is rated in Amps, that is the fuse or circuit breaker size
you will need. If rated in Watts, you will have to use the
formula P=IE, where P is power in Watts, I is current in Amps,
and E is Electromotive Force in Volts. Since we know the watts
and volts, we solve for current, thus: I=P/E, and I will be your
current rating.
One note: These calculations give the MINIMUM rating needed for
the motor to run. Fuses and circuit breakers are usually
designed so that they will break if the circuit pulls 250% of
the Motor's rating.
Also, have a read here :
HTML http://www.the12volt.com/info/recwirsz.asp
:thumbs: :thumbs:
#Post#: 68423--------------------------------------------------
Re: Fuses
DIR By: ashcrroft752
Date: July 19, 2013, 9:07 am
---------------------------------------------------------
If I don't know how many amps or watts a component draws how
would I measure this?
I have a multi meter but have never used it to measure amps or
watts I'm looking for basic instruction on how to do this.
For example should I be measuring across the feed terminal to
the earth of taking off the earth and measuring the volts/amps
the motor is leaving unused? It's new to me an I'd like to
learn.
#Post#: 68426--------------------------------------------------
Re: Fuses
DIR By: Arjan
Date: July 19, 2013, 10:53 am
---------------------------------------------------------
If this is all new to you, I'd suggest you do some reading
before starting it all.
I've been building them for years and it takes practise...
These are a good staring point :
HTML http://thumbs4.ebaystatic.com/d/l225/m/metyT9uZERpY5nufZazkcIA.jpg
HTML http://i.ebayimg.com/t/Auto-Electrical-Car-Guide-DIY-Wiring-New-Haynes-Manual-/00/s/NDUwWDMzNg==/z/KAEAAOxy-o5R2UBl/$T2eC16JHJHsFGlhN24MhBR2UBlHFEQ~~60_35.JPG
#Post#: 68427--------------------------------------------------
Re: Fuses
DIR By: ashcrroft752
Date: July 19, 2013, 11:12 am
---------------------------------------------------------
I've built several looms, I've just never bothered to fit the
correct fuses before.
#Post#: 68446--------------------------------------------------
Re: Fuses
DIR By: espacekiller
Date: July 19, 2013, 6:34 pm
---------------------------------------------------------
One of your main concerns with a fuse is that it protects the
Wire to prevent overheating or a fire, so Say you are using a
cable rated at 15 amps, you need to fuse it at below 15A. (more
like 12A or 10A in practice)
It is best to over engineer it if anything to allow for damage
poor connections etc.
You can measure the current (amps) by wiring your multimeter in
series with the device so it is fed through the multimeter,
however you may only have a 1A and 10A range so anything drawing
more than 10A I going to blow the internal fuse inside the
multimeter.`
from my experience the first thing you need is a load of
replacement fuses for the multimeter. :rolleye0012:
#Post#: 68452--------------------------------------------------
Re: Fuses
DIR By: ashcrroft752
Date: July 20, 2013, 2:36 am
---------------------------------------------------------
A load of multi meter fuses and leave the back of it then
:thumbs:
#Post#: 68464--------------------------------------------------
Re: Fuses
DIR By: Mr.Pickles
Date: July 20, 2013, 6:14 am
---------------------------------------------------------
--- Quote from: ashcrroft752 link ---
>
> A load of multi meter fuses and leave the back of it then
:thumbs:
>
--- End Quote ---
NOOOOOOOOOOOOOOOOOOOOOOOOOOOOO! :smiley-furious: :2mo5pow:
:smiley-furious:
Put the back on with sticky tape!
If you leave it off, you'll put it down on something conductive,
like a Land Rover, the PCB on the back of the meter will short
out and blow it up!
Then you'll need a new meter and you can bet all the fuses you
bought for the first one, won't fit! :rolleye0012:
Mr.P
#Post#: 68473--------------------------------------------------
Re: Fuses
DIR By: ashcrroft752
Date: July 20, 2013, 8:16 am
---------------------------------------------------------
Good point.
*****************************************************
Page 1 of 1