DVD3500 Posted March 1 Report Share Posted March 1 I am breaking my project down into "modules" i,.e suspension, body, motor/transmission etc and one big aspect is more or less restoring/upgrading the wire loom i.e. electrics. I presume it was done according to some British standard. I actually have 2 looms from the two cars I bought (`72 European and `76 Federal) plus a guy gave my a European MKIV loom of unknown model year so I have lots to check. However, should I need to replace a wire/cable I would want to get as close to original as possible (or even slightly larger...) I did several searches but all I could find was the European standard: https://en.wikipedia.org/wiki/IEC_60228 But I am not sure what standard was used on our cars so no clue what the equivalents are. (I do have the Lucas chart for the standard of what colors are used for what on a typical loom) Just buying a new loom doesn`t make sense because the car will have multiple upgrades such as relays for headlights, upgraded heater, possibly subtle DLRs/fog lights etc... Engine mgmt will also be nonstandard... Cheers and have a great day! Link to comment Share on other sites More sharing options...
Wagger Posted March 1 Report Share Posted March 1 (edited) Our cars were designed when we used British Standards. These were superceded by Systemes Internationale (SI) in the 1970's. Then they were rationalised under the EU as ENsomething. They still apply. They were aligned with all European Countries including those not in the EU. USA and Canada use UL and CSA. They differ from EU standards. Use a fuse box and fit fuses to protect the wire size. That is what fuses are for, contrary to the thoughts of those who use nails. 'Moderns' now have fuses in the battery post connectors. You do not need to go to that extreme unless you are going to use the starter to drive you when the engine fails. These cars do very well with just three fuses, but it makes fault finding tricky. Edited March 1 by Wagger Link to comment Share on other sites More sharing options...
DVD3500 Posted March 1 Author Report Share Posted March 1 So simply measuring inner and outer diameters suffices? Resistance etc is the same? Link to comment Share on other sites More sharing options...
JohnD Posted March 1 Report Share Posted March 1 DVD, Someone who makes Spitfire looms might add the wiring you want for upgrades, if you specify where the new wiring must go and the position of the components it supplies, to make you a bespoke loom. I can't suggest who you should ask, but you are clearly good at research! John Link to comment Share on other sites More sharing options...
Wagger Posted March 1 Report Share Posted March 1 4 minutes ago, DVD3500 said: So simply measuring inner and outer diameters suffices? Resistance etc is the same? I always go by the Cross sectional area. This means measuring the diameter of the copper content, halving that to get the radius. then using pi r squared in order to get the CSA. Having worked in that industry for over 40 years, I just use my judgement (eyes and fingers) and fit a fuse up to 0.7 of the rating. Most reels of wire can be bought using the Cross Sectional Area specified. The reels are marked if you are lucky. If you double the CSA, the resistance will be halved. 1 Link to comment Share on other sites More sharing options...
dougbgt6 Posted March 1 Report Share Posted March 1 48 minutes ago, Wagger said: You do not need to go to that extreme unless you are going to use the starter to drive you when the engine fails. I had to do that to get off a roundabout under the M4 after head gasket failure. It was at that point I decided an ammeter wasn't such a good idea, got VERY hot. Installed a voltmeter and 10 way fuse box. Doug Link to comment Share on other sites More sharing options...
ahebron Posted April 12 Report Share Posted April 12 One tip I will give you is earths earths and earths. Make sure you give as much as you can a decent earth/neutral return wire. I cant recall the wiring on the Spitfires but my Vitesse relies heavily on the body as a return path and with older cars and restored cars these paths can be compromised. Corrosion on older cars and paint and insulation on restored cars. It doesn't take much to run a nice black neutral cable to the various electrical items on our cars. I also add earth points to the front side lights as they rely on the bonnet for a return path. 1 Link to comment Share on other sites More sharing options...
JohnD Posted April 12 Report Share Posted April 12 + one for ahebron's advice! And especially rear light clusters. You need a earth wire that will rake the current from ALL the lights at once! After all, you could be at night, lights on, indicating AND then brakes on! Joh 1 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted April 12 Report Share Posted April 12 On 01/03/2024 at 10:32, Wagger said: You do not need to go to that extreme unless you are going to use the starter to drive you when the engine fails. Long long time (1988?) since I did that, in a Landrover that had run out of fuel. Re fuses: after the GT6 took the head staggers and blew one fuse every left turn leaving me with no wipers, indicators, stop lights, heater etc in pouring rain I fitted a six-fuse box in both Heralds during rebuild so that if something goes, they all don't follow suit. Easy to do and hopefully not needed, but there if it is, and better than the standard Herald system of no fuses at all. 1 Link to comment Share on other sites More sharing options...
Wagger Posted April 12 Report Share Posted April 12 7 hours ago, Colin Lindsay said: Long long time (1988?) since I did that, in a Landrover that had run out of fuel. Re fuses: after the GT6 took the head staggers and blew one fuse every left turn leaving me with no wipers, indicators, stop lights, heater etc in pouring rain I fitted a six-fuse box in both Heralds during rebuild so that if something goes, they all don't follow suit. Easy to do and hopefully not needed, but there if it is, and better than the standard Herald system of no fuses at all. A good idea, especially if you label all for reference. Saves loads of time when fault finding. 1 Link to comment Share on other sites More sharing options...
Morgana Posted April 14 Report Share Posted April 14 (edited) Outer diameter can be misleading as newer wiring is 'thin wall' so there's a larger area of copper for a given diameter compared to your old loom. The only real way to ensure satisfaction is to calculate or estimate the load on each wiring element, then check the voltage drop along the wire length is not excessive. Taking the load off is also beneficial. Adding headlight relays over the front wheel arch with a new feed means the dashboard switch in the Herald is not in danger of catching fire as it was because of the previous owner's loose connections, and the headlights are brighter. You might find the attached table useful. I get wires from Auto Electric Supplies. They have a good range of colours that match the Lucas tables, and plenty of cross sectional areas available with recommendations as to their suitable uses. Edited April 14 by Morgana 1 Link to comment Share on other sites More sharing options...
ed.h Posted April 15 Report Share Posted April 15 (edited) Period British stranded wiring was specified by the number of small strands (each 0.3 mm diameter, I believe). Here is how they relate to the US AWG system: Edited April 15 by ed.h 1 Link to comment Share on other sites More sharing options...
DVD3500 Posted April 15 Author Report Share Posted April 15 Gosh thanks for all this! Very very useful and helpful! Link to comment Share on other sites More sharing options...
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