| 1) Do not ever use THHN/THWN wire. This wire | | | | 8) If at all possible, use stainless hardware to fasten |
| (insulation) classification is not rated for automotive | | | | all primary cables. Some galvanic or plated hardware |
| use. Cars move and vibrate which chafes the | | | | can cause dissimilar corrosion and can sometimes |
| insulating material. | | | | carry more impedance that its stainless counter parts. |
| 2) A wire that is rated for A/C voltage may have a | | | | On smaller secondary circuits, this is not as important. |
| different rating when used in low voltage D/C | | | | 9) Battery storage. Keep batteries away from |
| applications. Your house uses A/C, your car uses D/C. | | | | humidity. Keeping it charged will prolong its life. If a |
| 3) The best primary power cable is a type TEW or | | | | battery is dead, cool it before you charge it. Put in |
| MTW (Machine Tool Wire) as its rated for continuous | | | | the refrigerator or outside if its cold. Cool batteries |
| use with higher amperage loads. | | | | charge better. |
| 4) OFC (oxygen free copper) is by far the best | | | | 10) Batteries specifications and charge rates are for |
| cable for automotive use. However, it is expensive | | | | 77 degrees Fahrenheit. Temperature variations will |
| and requires a quality crimper and should be soldered | | | | change charge rates. |
| for security. The most common application for this | | | | 11) Use relays. Anytime you want to switch a device |
| wire is high-end car stereo applications. | | | | that draws more current than is provided by an |
| 5) If you are like me, you may choose to skip OFC | | | | output of a switch or component you'll need to use a |
| and go with TXL wire. TXL (thermal cross-linked) | | | | relay. The coil of an SPDT relay that we most |
| wire is next best. TXL wire has twice the voltage | | | | commonly use draws very little current (less than |
| rating of standard GPT (general purpose) wire. Most | | | | 200 milliamps) and the amount of current that you |
| high-end harnesses are made with this wire. If you | | | | can pass through a relay's common, normally closed, |
| want to keep your ride for the long haul, you may | | | | and normally open contacts will handle up to 30 or 40 |
| want to pony up for a harness made with this wire. | | | | amps. This allows you to switch devices such as |
| 6) The best connection is a properly done solder | | | | headlights, parking lights, horns, etc., with low |
| joint. If you aren't sure how to solder, crimp the | | | | amperage outputs such as those found on keyless |
| connection then solder it. Cold solder joints not only | | | | entry and alarm systems, and other components. In |
| introduce resistance, but they can come apart. | | | | some cases you may need to switch multiple things |
| 7) Keep your grounds as short as possible. It is far | | | | at the same time using one output. A single output |
| better to have a few more connections than a long | | | | connected to multiple relays will allow you to open |
| ground that can build heat and introduce ground | | | | continuity and/or close continuity simultaneously on |
| loops. It is common practice to run a ground wire | | | | multiple wires. |
| from a high demand devise such as a fuel pump back | | | | 12) Most electromechanical devises are rated |
| to the battery. This not only adds additional loads to | | | | according to the MTBF (Mean Time Between |
| the pump or devise but also can lead to device | | | | Failures). You improve your odds of a long MTBF by |
| failure. Have you ever seen a production auto with a | | | | keeping your electrical devices in a low humidity, low |
| ground cable longer than the positive cable? | | | | heat environment. |