Capstone Project Wiki

For electrical projects, wiring can make the difference between success and failure. Good wiring practices not only facilitate proper connections and troubleshooting, they also increase the likelihood of the project working long-term.

The following are some tips for improving the quality of wiring in your projects. Note that some of these rules apply mainly to products like machinery, where there are lots of wires and size and shape of the enclosures are not important.

• Use a commercially-available enclosure, unless you have a need for a custom enclosure as part of your product.
• Make the enclosure larger than you think you will need. Crowded wiring is hard to make and hard to troubleshoot.
• Mount circuit boards securely in the enclosure, using commercial-quality components. Add shock-absorbing mountings if your system is exposed to shock or vibrations.
• Consider using individual DC-DC power converters for each board in your system to minimize power-supply noise.
• Consider using isolators between boards and subsystems to reduce the effects of noise propagation.
• Use bulkhead connectors to get connections through the enclosure wall. Running wires through holes in the enclosure generally makes it harder to troubleshoot and repair.
• Use terminal strips inside the enclosure to make the internal connections.
• Use different colors of wires for different signals. Troubleshooting problems when all the wires are the same color is nearly impossible.
• Use appropriate wire gauge for your connections. Wires that are too large or too small cause problems.
• Label the wires with a circuit number.
• Use appropriate, high-quality connectors for each board in your system. Don't use audio connectors to carry high-power signals. Be sure you understand the electrical specifications of the connectors.
• Use keyed and locking connectors where possible.
• Avoid identical connectors for different uses. If a user can physically connect things wrong, they eventually will.
• Using a wiring harness. Make your wiring layout clean. Use wire looms, cable chases, cable ties, and other devices inside the enclosure to make the wiring neater.
• Include stress relief points to prevent wiring from flexing near connectors or solder points.
• Use stranded wire, rather than solid wire. Solid wire will eventually break.
• Use a single ground point to avoid ground loops.
• When using shielded cables, ground only one end of the shield.
• If noise is an issue, use twisted pairs.
• Don't make your own twisted pairs. Buy shielded-twisted-pair cable with an external sheath to carry multiple signals.
• Pay attention to any needed fuses or circuit breakers.
• Look at some commercially wired boxes to get an idea what professional wiring looks like.