ausmini :: View topic - electrical values

Don't forget with the lighting, what comes in, must go out, so make sure the negatives from the bulbs are the same gauge as the supply wires.

2.5mm^2 cable is good for 25 amps, 1.5mm^2 cable is good for 20 and 1.0mm^2 cable is good for 16 Amps. These values vary a little on application, but this is pretty well spot on for the application here.

The highest consuming circuit on your car is the headlamps. 2 x 100 watt H/Beams = 200w/12v = 16.6 Amps. Consider wiring these in 2.5mm^2. You will notice even standard lighting to get brighter if you do this and add a relay. That way it won't ever matter what bulb goes in the front, the mini 's electrical system will simply shrug it off and continue on it's merry way.

2mm 5-10a
3mm 10-20a
4mm 20-30a
5mm30-40a
6mm 50+ a

I got the A.S. reference here in front of me. The values you use are fine and just dandy for worst case scenarios. For example fully enclosed in heat insulate material. Minis are not, they're just bundled and mostly air cooled. So hence the values I've given. I had a checkers of my ref before I posted to be sure to match the environment.
The wire sizes you use are a simple measurement of diameter, not cross sectional area, that is why the numbers differ. Auto sparks like to do this cos it's simpler for their heads to figure out.

for eg. 3mm(incl. insulate) = 2.5 mm^2 =10 amps (worst case, maybe wrapped in thermal insulation) or up to 32 amps on it's lonesome in a cool environment. table B2

Oh, and your maths is fine, it's just a permutation of the ones I gave. P=vi, I=P/v and V=p/i

but if ar=av therfore r=v ??
and what is p/w? P-power (watts) then what is w?
is this new jargon to confuse old salts?

Do auto spark apprentices now use 'a' instead of 'i' to indicate current?

You going to Cavendish road Tafe?

i go to moreton at the mt gravatt campus

yea the food from the cafetiria isnt the best .. i onli eat the hotdags with cheese ... an some times the chips .. but they both arent the best ..

any chance anyone knows the electrical values (amps) of the ignition, stop lamps, dirrection lamps, head lights, heater unit and park lights,

reason is i wanted a few extra fuses so i modified a loom to take a ten fuse fuse box, i just need to make sure nothing needs thicker wiring and what sort of fuse to use. i looked at other looms but they are different cars and hold different values(relays and other circuits),

cheers

Author:	buztoy [ Wed Feb 21, 2007 5:38 pm ]
Post subject:	electrical values
any chance anyone knows the electrical values (amps) of the ignition, stop lamps, dirrection lamps, head lights, heater unit and park lights, reason is i wanted a few extra fuses so i modified a loom to take a ten fuse fuse box, i just need to make sure nothing needs thicker wiring and what sort of fuse to use. i looked at other looms but they are different cars and hold different values(relays and other circuits), cheers

Author:	Mick [ Wed Feb 21, 2007 5:55 pm ]
Post subject:
You can go through individual values for the current usages around the mini, but all you really need to know is that 2.5mm^2 cable is good for 25 amps, 1.5mm^2 cable is good for 20 and 1.0mm^2 cable is good for 16 Amps. These values vary a little on application, but this is pretty well spot on for the application here. The highest consuming circuit on your car is the headlamps. 2 x 100 watt H/Beams = 200w/12v = 16.6 Amps. Consider wiring these in 2.5mm^2. You will notice even standard lighting to get brighter if you do this and add a relay. That way it won't ever matter what bulb goes in the front, the mini 's electrical system will simply shrug it off and continue on it's merry way. For the rest, you are only talking 5 Amps at the most. Ignition draws the lion's share, but indicators are pretty insignificant, mostly around an amp at most for say the brake lights, similar for indicators, even less for parkies. This means you can comfortably wire the car using the one gauge except for the lighting circuits and +ve supply feed to the ignition switch from the solenoid/battery and from there to your fuse box. All feeds to the fuse box should be larger than the combined outgoing load current. Also use 6mm (at the least 4mm) on the cables from the alternator to the battery/solenoid. I've never measured a fuel pump, but would expect it to be less than 5 amps as well. Correct me if there's another cable or two I've forgotten anyone.. Don't forget with the lighting, what comes in, must go out, so make sure the negatives from the bulbs are the same gauge as the supply wires. Just for reference, standard mini wiring is 1.0mm^2 and pretty crummy conductors at that. Next best thing you can do for you mini if you must make your own loom is to solder the connectors. Do this by removing the coloured insulators on the store bought items and soldering away.

Author:	buztoy [ Wed Feb 21, 2007 6:05 pm ]
Post subject:
Quote: Don't forget with the lighting, what comes in, must go out, so make sure the negatives from the bulbs are the same gauge as the supply wires. i did forget it actually, i was going to put stop/dirrection on the same fuse at about 15amps, inside lights i put with headlights, the headlamps only using 16amps i thought they would have used at least 25 - 30

Author:	Mick [ Wed Feb 21, 2007 6:10 pm ]
Post subject:
Nope, it's straight maths and with the simplicity of DC too (AC involves crazy stuff as frequency goes up and down). I = P/V and V = I x R. Use those two formulas and you're laughing. And with the lights ONLY using 16 amps, it's easy to forget just how much juice that is till you see it melt something and then burst into flames. It is alot of juice, we're just used to it. As an example, it (arguably, and probably unlickily) takes 0.016 of an Amp to stop your heart, you just need a voltage high enough to force this through the body. With so many smaller circuits, think about smaller fuses to suit the load, no use saving a ten cent fuse by burning out the loom in it's place.

Author:	MiniMan_Alis [ Wed Feb 21, 2007 6:31 pm ]
Post subject:
Mick wrote: 2.5mm^2 cable is good for 25 amps, 1.5mm^2 cable is good for 20 and 1.0mm^2 cable is good for 16 Amps. These values vary a little on application, but this is pretty well spot on for the application here. The highest consuming circuit on your car is the headlamps. 2 x 100 watt H/Beams = 200w/12v = 16.6 Amps. Consider wiring these in 2.5mm^2. You will notice even standard lighting to get brighter if you do this and add a relay. That way it won't ever matter what bulb goes in the front, the mini 's electrical system will simply shrug it off and continue on it's merry way. jesus what kind of wiring do you use i am learning all about wiring looms an ristance an all that jazz but holy fk 2mm 5-10a 3mm 10-20a 4mm 20-30a 5mm30-40a 6mm 50+ a an the triangles to figure out V,A,R and P/W,A,V v ......p/w a r......a v v=a x r, a=v / r, r=v / a p/w= a x v, a=p/w / v, v=p/w /a hope that makes sense

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Author:	Mick [ Wed Feb 21, 2007 6:35 pm ]
Post subject:
Quote: 2mm 5-10a 3mm 10-20a 4mm 20-30a 5mm30-40a 6mm 50+ a I got the A.S. reference here in front of me. The values you use are fine and just dandy for worst case scenarios. For example fully enclosed in heat insulate material. Minis are not, they're just bundled and mostly air cooled. So hence the values I've given. I had a checkers of my ref before I posted to be sure to match the environment. The wire sizes you use are a simple measurement of diameter, not cross sectional area, that is why the numbers differ. Auto sparks like to do this cos it's simpler for their heads to figure out. for eg. 3mm(incl. insulate) = 2.5 mm^2 =10 amps (worst case, maybe wrapped in thermal insulation) or up to 32 amps on it's lonesome in a cool environment. table B2 Oh, and your maths is fine, it's just a permutation of the ones I gave. P=vi, I=P/v and V=p/i but if ar=av therfore r=v ?? and what is p/w? P-power (watts) then what is w? ristance = resistance ? is this new jargon to confuse old salts? Do auto spark apprentices now use 'a' instead of 'i' to indicate current? You going to Cavendish road Tafe?

Author:	MiniMan_Alis [ Wed Feb 21, 2007 7:55 pm ]
Post subject:
Mick wrote: I got the A.S. reference here in front of me. The values you use are fine and just dandy for worst case scenarios. For example fully enclosed in heat insulate material. Minis are not, they're just bundled and mostly air cooled. So hence the values I've given. I had a checkers of my ref before I posted to be sure to match the environment. The wire sizes you use are a simple measurement of diameter, not cross sectional area, that is why the numbers differ. Auto sparks like to do this cos it's simpler for their heads to figure out. for eg. 3mm(incl. insulate) = 2.5 mm^2 =10 amps (worst case, maybe wrapped in thermal insulation) or up to 32 amps on it's lonesome in a cool environment. table B2 Oh, and your maths is fine, it's just a permutation of the ones I gave. P=vi, I=P/v and V=p/i but if ar=av therfore r=v ?? and what is p/w? P-power (watts) then what is w? is this new jargon to confuse old salts? Do auto spark apprentices now use 'a' instead of 'i' to indicate current? You going to Cavendish road Tafe? yea we use these values for loom wiring (wraped up eg modern cars) and the measurement we use dont really have anything to do with OD,CSA its just .. sh!t .. lol .. no r doesnt = v its jus the way the triangle works yea p/w means power/watts i do that jus so if it say find p i jus like 2 put w there aswell yea we use i but i like to use a cuz yea sameish reason as b4 i go to moreton at the mt gravatt campus

Author:	Mick [ Wed Feb 21, 2007 8:23 pm ]
Post subject:
Quote: i go to moreton at the mt gravatt campus Alma Mater, class of '92! Ahh the crap from the cafeteria used to block me up for weeks...

Author:	MiniMan_Alis [ Wed Feb 21, 2007 8:31 pm ]
Post subject:
yea the food from the cafetiria isnt the best .. i onli eat the hotdags with cheese ... an some times the chips .. but they both arent the best ..

Author:	Mick [ Wed Feb 21, 2007 9:11 pm ]
Post subject:
MiniMan_Alis wrote: yea the food from the cafetiria isnt the best .. i onli eat the hotdags with cheese ... an some times the chips .. but they both arent the best .. Watch the lasagne. And the steak they don't sell one day becomes the sausages the next, and then they use those for the curry the day after...

Author:	Mike [ Wed Feb 21, 2007 11:37 pm ]
Post subject:	Re: electrical values
buztoy wrote: any chance anyone knows the electrical values (amps) of the ignition, stop lamps, dirrection lamps, head lights, heater unit and park lights, reason is i wanted a few extra fuses so i modified a loom to take a ten fuse fuse box, i just need to make sure nothing needs thicker wiring and what sort of fuse to use. i looked at other looms but they are different cars and hold different values(relays and other circuits), cheers I wouldn't fuse the coil power supply (from the ignition switch) or atleast put it on its own blade fuse as if a fuse blows (or moves out of its holders or simply breaks like those crap glass items do) while youre driving - the engine will stall - possibly dangerous. Another thing you can do to avoid running thick gauge, high amperage power supply through the bulkhead and to the ignition switch, and if you wanna complicate matters further, is to use a relay for all your ignition actuated circuits. THIS IS ESPECIALY USEFULL if you have heaps of sound equipment for example which draws alot of current when the ignition switch is in its "on" position. So run a 30amp +12 wire from the solenoid to the relay, and feed the "on on ignition" parts of your fuse box (like the one feeding the wipers and heater fan, stereo etc) from the relay. And then the relay is activated by the ignition switch (thus very much like a lighting relay you avoid running all the current through the 30 year old switch). Oh and its not wise to run anything else on the headlight fuse (which should be 25-30amp) as the amperage on that fuse is too great. Your arrangement (headlights + interior lights on the same fuse) doesnt make much sense as if your headlights blow the fuse at night you'll have to operate in total darkness without your interior light once you stop the car. Plus the wiring to the door switches and the interior light will burn long before the 30 amp fuse does. Best use a separate fused relay for the headlights (a double lighting relay like the 'New Era" item is best) and put the interior lights on the same circuit as the rest of the "always on" auxilary instruments (like the horn). At the same time run the sidelights, number plate lamp and the instrument lighting on the same fuse as they are all activated at the same time by the same switch (lighting switch middle position). The indicators could be on this fuse or on the "on on ignition" auxilaries fuse (like the wipers etc).

Author:	buztoy [ Fri Feb 23, 2007 4:16 pm ]
Post subject:
good point im gonna move that interior lighting to another fuse, i have another fuse holder spare, im also adding under the bonnet lights and boot light onto that fuse, imgonna follow with what you told me with the acc and auxilary relay but that would require a larger relay, true?

Author:	Mick [ Fri Feb 23, 2007 4:33 pm ]
Post subject:
Not really, a 20 amp relay would do fine. You use a 25 to 30 amp fuse so as to give the lights some headroom in the normal operating environment. It's no use using a 16 amp fuse on 16 amp lights because it would blow too easily. The fuse should only blow when a current too large to be something other than a short is passed. The cable would be fine for this short period, and so would the relay.

Author:	buztoy [ Fri Feb 23, 2007 4:51 pm ]
Post subject:
so what size relay, is there a rating, im a little wary of using a normal 4 pin relay

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Author:	Mick [ Fri Feb 23, 2007 5:00 pm ]
Post subject:
There's nothing wrong with normal relays, if you buy a decent brand you will have no problems, and they aren't expensive considering. I've got two in front of me, both your normal everyday relay shape. One is rated for 40 amps (single switching) and the other is rated for 15 amps (changeover type, good for high to low beam switching), so just check the packaging for the Amp rating you're after. If a 40 amp one pops up at the right price then this would be fine for the main relay, otherwise anything at or over 20 would also do for most applications.