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Should I rewire my car?
by Steve Jack'Stands" Jack

Here we go again folks on a no nonsense approach to technical issues that come up often. The next series of articles over the next few months will feature your cars electrical system, components and design.

The first section is reasons and questions that you should investigate to decide whether or not you should rewire a that car you bought or some food for thought going forward with that new project as well. I consider this a safety issue moreover than anything else. Again, this is a general dissertation on automotive wiring and should not be taken as an answer to all issues and/or problems.

  1. Consider scrutinizing newly or recently built rods and cars for electrical system quality and reliability if you don't know for sure who installed the system. Recently as a few years ago, some wiring companies had problems with their designs and quality. Look closely at your system and determine the manufacturer and era of the electrical system. Contact the manufacturer for past problems they might have experienced. Sometimes problems only needed time and use for these issues to arise. Some systems may also have crimps and connections that are not constructed properly or pieced together wiring systems that make for a wiring mess! Check it thoroughly.
  2. Regardless of how well that Little Old Lady From Pasadena kept that super stock Dodge that you are buying and that original wiring looks good and is functioning well, be aware that time and air chemistry has been doing a job on the old wiring. Moisture, heat, cold and ozone have been at work for years breaking down the plastics in insulation and connectors. Telltale signs of this problem are brittle, cracked and/or faded insulation, but not always shows up as such. Autos built before 1975 should be automatically scrutinized for this issue. Under the hood heat will exaggerate this problem. Start there first.
  3. Moisture/humidity contamination in wires/connectors is reflected by copper-oxides that form and leave greenish/whitish powdery spots on the connectors and even migrate up the wire inside the insulation, unbeknownst to a casual observer. As these spots become more corroded they also become so resistive that they not only degrade the component function that they are feeding, but can become dangerously hot due to the resistive component of the connection or wire. When the corroded junction becomes increasing hot, the copper anneals itself furthering its resistive component and becomes even hotter. This creates a considerable fire hazard, especially with the old cloth and plastic wiring insulation and should be looked at carefully.
  4. We continue to add electrical related accouterments to the car's system without adequate design and capacity for such. High current goodies such as power windows, power seats, cooling fans, airconditioning, stereos and even high wattage headlights warrant larger wire sizes, fuses and system upgrades. Piecing the system together with parts and add-ons adds resistive connections and degrades the overall reliability of the electrical system that was not originally designed for such. Even simple tasks such as battery charging can be degraded with inadequate design. Adding a simple upgrade of high wattage headlights may exceed the capacity of the headlight switch to handle and cause the internal breaker of the switch to profusely cycle.
  5. In conjunction with above, we add all the electrical demand and reason that we should fulfill that demand with new fangled, high output alternators. This idea is generally good, but the wiring in the original system may and probably will NOT be capable of sustaining higher current demands. This potentially can cause connectors and wires to heat up with increased current and cause the dreaded annealing situation to raise its ugly head. These high output alternators require special consideration for correct application and function.
  6. Battery and charging circuits, as mentioned above, require special design attention to function correctly. The proliferation of moving batteries to remote locations such as trunks and behind the seats requires substantial upgrades in feeding/charging wires from the alternator to the battery and main feeder wires that go from the battery to the starter solenoids or other major feeding junction. This mainly has to do with not only capacity, but distance to the source as well. Poorly designed or inadequate capacity in the charging and feeding circuits cause a whole plethora of symptoms and ills that effect starting, charging and simple electrical component function. Newer wiring systems address these issues effectively.
  7. Yesterday's wiring technology is antiquated by today's standards! That should be enough said for a good look at what you have, where you are going, and the performance you ultimately want. Better connectors, user friendly modularity, superior heat-resistive wiring, increased wire capacity, compact and functional fuse box technology, and component integration design are all ingredients for reliable, safe, functional and worry-free performance, just like the OEM systems of today. Moreover, these new systems are high quality and reasonably priced and are cheap insurance for a care free ride!

Get wired for a safe ride!

This is the second section on wiring and electrical issues for you car that focuses on general design and selection of your wiring system or kit. As always, this is not a substitute for doing your own homework, but a general dissertation and helpful tips on some things to think about going forward on your wiring project.

  1. Size your system to the number of circuits that you have need of and never "double up" or "piggyback" circuits together. The individual circuits are designed by the manufacturers to only provide a certain amount of current protection, which means the fuse size and moreover the wire size is designed for the applicable circuit. "Piggybacking" can lead to over current issues and result in catastrophic failure and damages. Make sure the system has ancillary/accessory expansion capacity for future loads and use them appropriately. Usually, 18 to 23 primary circuits will suffice for the biggest electrical demand/accessory list for any rod. Smaller systems will suffice for less gadget-ed rides.
  2. 2. Do your homework and count watts/amps for each component that you put in the vehicle and make sure your wiring system is sized correctly for each application. Wattage ratings should be divided by 12 (as in 12 VDC) to get a ballpark operating current (example...most cooling electrical fans are rated at 240 watts, so the current to run one of these it typically 20 amps continuous). Also make sure that the DC bus/feeder (the main line the feeds the fuse block from the battery/charging source) is sized to handle the entire component's current appropriately. Here is a good web sight for correct wire sizes/current/distance run Ample Power.
    Typical component amperages table
    Loads given are at measured voltage of 12.6 Volts
    Cooling fans 15-40 amps
    Air conditioning systems 15-20 amps
    Aftermarket headlight systems 12-20 amps
    Stereos - Non-amplified 10-15 amps
    Amplifiers - see instructions with amplifier 30 amps
    Ignition systems - Standard Less than 10 amps
    Ignition systems - Special 10-15 amps
    Power windows/Trunk lifts 10-15 amps(Intermittent)
    Accessory circuits 15 amps
    Windshield wipers 10 amps
  3. Make sure that your wiring kit is designed to direct the charging circuit to either the battery or the battery post on the starter solenoid shared with a battery feed DIRECTLY. NO CHARGING THRU THE FUSE BLOCK... PERIOD! This creates too many connections and the addition of resistive length to the charging wire. Well-designed charging/wiring kits will feature large wires (i.e., at least an #6 or bigger and/or some offer multiple wires to accomplish this which allows for enough circular mills) for connecting the alternator to the battery or the battery post on the starter. This assures proper current availability under all conditions.
  4. Choose wiring kits that feature high quality, high temperature insulated wires. Also, all large current circuits, including all main feeds and charging connections should be professionally crimped and soldered for higher joint/terminal integrity.

  5. Reliable wiring depends mainly on the integrity of the electrical connection/termination whether the connection is a power feed or a ground return. Most amateur automotive wiring gurus lack the quality crimping tools necessary to create a high quality, gas-tight seal at the joint, terminal or device. This gas-tight seal does several things including assures a high conductive connection, a high mechanical strength junction and a high resistance to corrosive atmospheric gas contamination, which is what degrades systems the most.

    In many cases with the use of garden-variety wire crimpers, you may find that the previously crimped ring terminal has fallen off even though the crimp looked good. This can be prevented by investing (and that's the correct word…investing!) in a professional grade wire crimper set from a professional tool company. Jenson tools carries one of the best line of professional grade tools for electrical use in the world. Usually, a ten-dollar bill, a quality crimper does not make! You might want to invest in a removable headed crimper to allow you to use multiple crimping heads for differing wire sizes, which also will work on spark plug wiring as well, a good side benefit for the money.

  6. Grounding is as important as the primary system wiring itself! Choose a wiring system that features ground wiring in the appropriate sizes and instructs you on how to correctly apply it. Multiple braided ground straps with the kits are a good start. Some kit manufacturers provide quality-grounding kits that completely take the car's frame out of the circuit. Frames can become resistive to electrical current due to corrosion internally. This is no different than a bad connection and separate grounding systems alleviate this. Prep of the grounding wires to the frame is important to stave off future corrosion and problems. Dielectric jelly can be used to help prevent connection degradation.
  7. Splices are often necessary when joining two or more wires. The best way to make a splice is to crimp the wires to a copper splice barrel, crimp, solder and heat shrink. Butt or end-to-end splices (red, blue and yellow etc) are acceptable when crimped properly. You should put heat shrink (the kind that comes with sealant/glue) over the butt splice for added protection to prevent moisture and atmospheric corrosion and eventual splice degradation.
  8. Choose a kit that features circuit labels and/or color coded wiring and hopefully both. Circuit labels every few inches is a must and some manufacturers feature color-coded wiring that actually match OEM colors. This makes wiring easy as well as any maintenance down the road a snap to identify the circuit. It also tells us that the vendor/manufacturer has gone to the trouble of detailing this important part of the product to make it more reliable and understandable.

    Mono-colored/labeled wiring kits can be okay, but are more difficult to trouble shoot and risk losing their labels to abrasion and automotive chemicals making circuit identification difficult for the most seasoned electrician.

    Also, time has proven that the various vendors and manufacturers that feature the OEM, GM designed fuse block have a product design feature (the fuse block) that has literally had decades of proven performance and wide application and are very reliable. This does not mean that other designs are not good. There are many quality ground-up designed kits that have very good reliability and adequate designs.

  9. When designing a wiring system include the use and design of auxiliary relays/panels. Consider relaying all components that are over 12 amps continuously. The auxiliary relaying will reduce the demand on the fuse block, increase working voltages to the respective components, reduce overall system voltage drop at the block and make trouble shooting components easier. This is the design standard in OEM applications today. This should include headlights (will make them brighter), large stereos/amps, cooling fans, airconditioning systems, power seats, power window motors and trunk lifting motors, etc. Use only automotive rated relays for these applications and size appropriately to current rating and circuit demands. Common relays are NOT adequate for these applications whereas they are not designed to operate in automotive and outside environments. Typically and minimally, rate your relays for 125% of the continuous load amperage.
  10. Always look for and use fusible links and/or master fuses in the wiring kits. This is a paramount safety issue! Master fuses in the battery circuits are a good alternative and can be found at automotive stereo shops, but without these devices you can burn your cool ride down to the ground. Don't forget to include fusible links in the charging circuit as well. Never put a fusible link inside the car or in close quarters with other critical wiring. Fusible links literally erupt when blown and could cause damage to other component and can be a serious fire hazard when inside the car. And, extending this same philosophy, do not over-fuse circuits because one of them is blowing a fuse all the time. Take the time to diagnose the problem and correct if necessary. Breakers are a great alternative to fuses in certain applications such as cooling fans, power window feeds etc.
  11. Finally, do your own homework and consumer surveying. There are enough web sites and personal relationships out there and wiring is a common topic among rodders. Research these kits on line, with buddies, acquaintances and other cars shops. Just like any other product, there are good, bad and ugly manufacturers and vendors out there. If you are not good at electrical skills, seek a professional to at least help or install your system.
Happy Summer Cruising!

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