In the interest of making our additions to the vehicle more easy to service and understand, I have created this Elecrtonic Wiring Standard.  Please abide by it where possible for your sake and others.  Please send additions or suggestions to Celia.

In all cases, make sure that you are using components that are rated for our operating conditions, including temperature ranges to 85C.

Cabling and Wire

Gauge Size

Select a gauge size based on the maximum current.  Below is a table I found on the Internet. I extracted out the part of the table most relevant to our application.  Currently (pardon the pun), we have lots of colors in the 20 and 24 gauge sizes.  We also have 2-conductor 14 gauge wire in red & black.  Stick with these sizes if they work for your application.

From: http://www.powerstream.com/Wire_Size.htm.

Load Carrying Capacities (see table below)
The following chart is a guideline of ampacity or copper wire current carrying capacity following the Handbook of Electronic Tables and Formulas.  As you might guess, the rated ampacities are just a rule of thumb. In careful engineering the insulation temperature limit, thickness, thermal conductivity, and air convection and temperature should all be taken into account. The Maximum Amps for Power Transmission uses the 700 circular mils per amp rule, which is very very conservative. The Maximum Amps for Chassis Wiring is also a conservative rating, but is meant for wiring in air, and not in a bundle. For short lengths of wire, such as is used in battery packs you should trade off the resistance and load with size, weight, and flexibility.

Wire Color

I have already done quite a bit of electronic wiring.  I am proposing a color system based on that, and suggestions from Peter Polidoro.  I'm also basing it on what we have available in the shop.  Let me know if more colors or signals need to be added.  Use common sense.

Stranded or Solid?

Always use stranded wire.  It holds up better under vibration.

Twisted Wire

When possible, twist or braid the group of single wires, either by hand or using the cordless drill.    This will help to maintain signal integrity.

Strain Relief

Where possible, consider adding strain relief to your cabling and wires.  Strain relief is often integrated into connectors---look out for it.  Other methods of strain relief include creating slack in part of the cable, and clamping it tightly at another.  Including loops is another option.  Tie wraps can be used for strain relief.  Test your strain relief by pulling on the wires.

Protection

All exposed cabling should be protected from sharp edges and the environment by "Flex Guard Tubing" (available at HdB and OSH).  It's the stuff already used by Polaris all over the vehicle.  It's round, corregated, and slit once along the length.  1/4", 3/8", and 1/2" sizes are available (I'm sure bigger is available too).  Use the 1/4" for a 2-3 wires, and larger sizes for more.  At each end of the tubing, and at any point where wires emanate from the tubing, wrap a piece of electrical tape around the tubing (see near the battery for examples).  This prevents the wires from coming out of the tubing.  Make sure that the tubing doesn't crimp the wire or cable.

Secure Your Wiring

Use the black tie wraps to secure your wiring to the vehicle.  Make sure that it won't bounce around much whie the vehicle is being driven.  Make sure that nothing will catch on your wires.

Connectors

When to Use Connectors

Use the smallest number of connectors possible.  Connectors are a leading point of failure.  However, connectors provide modularity.  Use them to so that subsystems can be removed and installed easily.  Use your best judgement.

Single-Wire Connectors

There are several types of single-wire connectors.  Here is the preference order:

1. First choice: quick diconnects
2. Second choice: ring tongue terminal (these havedisadvantage that you can't use loctite on screw will decrease conductivity)
3. Last choice: spade terminal (these have disadvantage that may come loose)

When possible, use insulated connection ends.  Use the right size connector for the wire gauge (should be labeled on connector box), and the right size crimping slot for the wire gauge.  The connector should be oriented in the crimping tool so that the dent is placed opposite the lenghtwise gap won the connector.

Note: the insulated connectors from OSH aren't all that great.  They don't provide enough strain relief---the wire can still move from size to side, stressing the crimped connection.  For proper strain relief (per Marc Thomas), remove the insulation with pliers, crimp the wire, then apply special 3-layer heat shink (Marc says it's available at HdB) that is super-heavy duty and has an adhesive on the inside.  (Check out the ground connection for the battery terminal block plate.  It was done this way.)

Splice Connectors

Make sure you really want to splice into an existing Polaris wire, or any other for that matter.  Practice on scrap wire of the same gauge before you make the final splice.

Multi-Pin Connectors

When possible, use the black AMP multi-pin connectors located at the Electronics bench in the shop (need connector name from John).  We have standardized on 4- and 9-pin versions.  Use the appropriate size.  See the instructions in the clear plastic box for more information.  Be sure to use the correct pin size and crimp tool setting for your wire gauge.  Use the panel-mount (bulkhead) type of connector body when you can mount the connector.  Use the additional parts to provide strain relief.

Use the body with the female pins for wires supplying power, and the body with male pins for wires receiving power.  This will minimize the chance of shorting the pins when the connectors are disconnected.

Heat Shrink

Use heat shrink to protect your wiring and provide strain relief.

Documentation

Document your wiring by following these steps:

• Create a schematic in DesignWorks Lite, available on the Windows machine in the shop (right John?), or for $40 on-line at http://www.capilano.com.
• Commit your design to the CVS tree.  Store it in the relevant parts subdirectory.  For example, the braking schematic would go under gc/parts/braking.
• Print out a hard copy and place it in the Vehicle How To and Maintenance binder located on the cart on wheels near the vehicle.  It's a white binder with a purple title page and spine.

Suppliers

Here is a list of electronics suppliers and their strengths and weaknesses.

HdB Electronics

2860 Spring Street

Redwood City, CA 94063

(650) 368-1388

only open during the week?

Has some of just about everything (electronic components).  May not have everything in a line.  Has Belden cable.  Sales people are knowedgable for the most part.  Inventory not on-line.  Not that cheap, but no shipping charges, and you get it now.

Fry's

340 Portage Road

Palo Alto, CA

(650) 496-6000

www.outpost.com

open on weekends

Has much smaller selection of electronic components than HdB, but more computers and accessories.  Watch out for previously returned items.

Digi-Key

www.digi-key.com

Incredible selection of electronic components, especially connectors.  Has decent on-line catalog, but I sometimes find it easier to use the hard-copy catalog (one located in shop library).

Belden

www.belden.com

Huge selection of wire and cable.  Almost too overwhelming.

Newark

http://www.newark.com/

Popular company for electronic components, but I find it difficult to do searches on-line.

OSH

2110 Middlefield Road

Redwood City, CA

(650) 365-7373

Okay selection of automotive-type electronics.

Radio Shack

Woodside Plaza

Redwood City, CA

(650) XXX-XXXX

You gotta be really desparate.

Other potential topics: ribbon cable (HdB has good supply: ribbon+IDC), multi-wire cable, soldering