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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 16809

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
apt100 wrote:
^^ the cross sectional area (eg 40mm2 or 35mm2 or whatever) is the area of the copper as this is what carries the current. It doesn't include the insulation Thumbs Up

and as you say it is just the area of a circle, so area= pi x radius x radius (and radius is half the diameter)

so, as above... 40mm diameter is 20mm radius, so area = pi x 20 x 20 = 3andabit x 400 = 1200mm2 andabit

edit: my reply was to steve


Whilst in practical terms this it true there is another factor which in critical applications may be significant (not in ours, though) which is that the number of strands has a bearing on the CSA as well.

If you have a single strand of copper which is 10mm diameter, the CSA will be pi times the square of the radius using the traditional simple formula. If you have a cable made up of, say, six smaller strands of copper laid up in a way where the overall outside diameter of the bunched conductors is still 10mm, the CSA will actually be less since you can never lay up circular conductors without gaps between them. So the downside is a reduction in CSA for the same overall size, but the upside is flexibility. As the individual conductors get smaller, so does the difference in CSA since the gaps get smaller.

On very heavy duty power cables etc you will find that the individual conducturs are not circular in cross section but shaped to minimise the inter-conductor gap.

Incidentally it is the gaps between the individual strands of copper in the injector harness of the TD5 that provides the conduit for the passage of oil from the engine to the ECU. If the conductors were solid, this phenomenon would not happen.
Post #724988 23rd Aug 2018 7:59am
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dorsetsmith



Member Since: 30 Oct 2011
Location: South West
Posts: 4554

Post #724990 23rd Aug 2018 8:07am
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apt100



Member Since: 05 Mar 2015
Location: Derbyshire
Posts: 1547

United Kingdom 2016 Defender 90 Puma 2.2 XS CSW Aintree Green
blackwolf wrote:
apt100 wrote:
^^ the cross sectional area (eg 40mm2 or 35mm2 or whatever) is the area of the copper as this is what carries the current. It doesn't include the insulation Thumbs Up

and as you say it is just the area of a circle, so area= pi x radius x radius (and radius is half the diameter)

so, as above... 40mm diameter is 20mm radius, so area = pi x 20 x 20 = 3andabit x 400 = 1200mm2 andabit

edit: my reply was to steve


Whilst in practical terms this it true there is another factor which in critical applications may be significant (not in ours, though) which is that the number of strands has a bearing on the CSA as well.

If you have a single strand of copper which is 10mm diameter, the CSA will be pi times the square of the radius using the traditional simple formula. If you have a cable made up of, say, six smaller strands of copper laid up in a way where the overall outside diameter of the bunched conductors is still 10mm, the CSA will actually be less since you can never lay up circular conductors without gaps between them. So the downside is a reduction in CSA for the same overall size, but the upside is flexibility. As the individual conductors get smaller, so does the difference in CSA since the gaps get smaller.

On very heavy duty power cables etc you will find that the individual conducturs are not circular in cross section but shaped to minimise the inter-conductor gap.

Incidentally it is the gaps between the individual strands of copper in the injector harness of the TD5 that provides the conduit for the passage of oil from the engine to the ECU. If the conductors were solid, this phenomenon would not happen.


Indeed. Quoted CSA are usually nominal, and depending upon the stranding the actual area will vary.
This table shows an example (it is American based, because I have easy access to it at home, but the principle is the same)



These wires are all nominal 8 AWG.
The first row is a solid conductor. Diameter is approx. 3.3mm and the area of the copper is approx. 8.4mm2. (This roughly matches the simple A=pi r2).
Row 3 shows a course stranded wire made up of 19 strands of wire, each of which are 21 AWG.
The diameter of the wire (excluding insulation) now goes up to 3.6mm, but the copper area comes down, to 7.8mm2.

In this table the true areas vary from 7.82mm2 to 8.63mm2, but they are all the same nominal size.

This was carefully calibrated for in my original formula by varying the "andabit" Wink

A practical consideration is that when crimping lugs to wire, the datasheet will often state that for finely stranded wires, such as welding cables, the next size up terminal might be needed to get the wire to fit.
Post #725103 23rd Aug 2018 7:16pm
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mike-sqft



Member Since: 14 Mar 2019
Location: Newyork
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United States 2000 Defender 90 2.5 TD Black LE Java Black
Is it as simple as working out the area of a circle from it’s radius? The website below makes it easy...just put the area as 40mm2 or whatever and it will tell you the Diameter of the circle or in this case the width of the wire.

From an electrical point of view though, I don’t know whether the mm2 measurement includes the insulation or not.

https://www.squarefootagearea.com/calculat...alculator/
Post #763429 14th Mar 2019 3:02pm
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 16809

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
The CSA of a conductor is just that, since the insulation is not part of the conductor it is not included in the CSA.

Why does anyone need a website to calculate circumference, area, and radius? It's such basic maths! Shocked Is nothing taught in school these days? Rolling with laughter
Post #763466 14th Mar 2019 5:22pm
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dorsetsmith



Member Since: 30 Oct 2011
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Is nothing taught in school these days? School no Whistle
Post #763469 14th Mar 2019 5:33pm
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custom90



Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19452

United Kingdom 
I have just been looking through a few old threads, so this is a bit of a thread revival, but this thread made me laugh quite a bit to be honest. Laughing
One of my favourite things about DEF2, as well as the wealth of knowledge as well.

I’m sure I’m not alone in searching through old threads for info as well, but the comments are what gets me every time.
Blackwolf seems to be on a roll lately. Whistle Rolling with laughter

On a more serious note, it would be useful to have a single dedicated and stickied thread for all battery cables sizes in MM2, Positive + Alternator and + Starter cables and also
Negative - Battery ground cable.
Their sizes in MM2 (which can be converted to AWG easily if needed)
For all generations of Defenders.

Unless there already is, the info is on here, and in the wiring schematics diagrams, but, it’s fragmented.
These cables specifically, are a common upgrade, and alternator output is also another common detail that would be ideal to collate for reference.
It would be easier to reference by year rather than VIN range, as it makes it quicker to check and easier to understand at face value without faffing around comparing details.

Perhaps Martin or PaulMC may consider doing this? I’m aware of the Puma 2.4 & 2.2’s wiring specs for these cables, but lack knowledge on earlier models and the diagrams for other years outside of the 2.4 2007 -2012 and 2.2 2012 to 2016 range.

Key*
(+ = Positive Live, - = Negative Ground, Insulation colour; R = Red, B = Black.
MM2 = CSA of the Conductor, EXCLUDES insulation and is the CSA size of the Conductor, not including Insulation I.e Outer jacket.
MM2 = Millimetre Squared
CSA = Cross Sectional Area, Excluding Insulation.
T Box = Transfer Box ground point stud.
Outer diameter of the cable including insulation typically is measured in millimetres, there are various types of insulation jacket. Silicone being flexible, thinwall, area saving, PVC, standard jacket pvc.
Alt = Alternator aka Electrical Generator.
WSM = Workshop Manual.


2.4 2007 to 2012 sizes are as follows;
Alt + R 25mm2
Batt + to Starter + R 40mm2

Batt - To T Box Ground B 40mmm2
Alternator Current Output 150A.

2.2 2012 to 2016 sizes are as follows;
Alt + R 25mm2
Batt + to Starter + R 50mm2

Batt - to T Box Ground B 50mm2
Alternator Current Output 150A.

As you can see, there was a slight CSA upgrade of an additional 10mm2 CSA Dia. for the later 2.2 compared to the earlier 2.4, but not upon the alternator to starter cable which remains the same at 25mm2.
The above details are actuate to the WSM Wiring Schematic, if any errors or omissions are present then anyone can feel free to notify.
Can anyone else add the details of other models that are accurate for earlier TD5, 200 & 300TDi and the appropriate years?
Hopefully, then we can collate that info into a singular post for fast and easy reference.

On a slightly off topic note, does anyone know if the 2.2 alternator mounting is any different to the 2.4?
Visually they look the same, and is the acc drive belt ribs quantity the same between the 2.4 and 2.2 on the pulley?
I’m pretty sure both can freewheel, saving fuel unless under load. High Output Alternators are out there but info is sketchy upon them based on fitment and pulley rib quantity. Diesels Lives Matter. ⛽️🛢️👨‍🔧🧰⚙️
And if You Love the Country, then we’re on the same side ~
I got’ love for Britain, I got’ British pride’. 🇬🇧
Post #1023496 3rd Feb 2024 8:31pm
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