Wire, Cables, and Harnesses

1.1 Wire & Cable Harness Requirements

Before starting any wiring work for Caltrans, Division of Equipment, it is recommended that prospective vendors refer to the most recent version of IPC-A-620 (Class 2). "Requirements and Acceptance for Cable and Wire Harness Assemblies". This document will be used by Caltrans inspectors as part of quality assurance acceptance inspections.

1.2 DC Wiring

1.2.1 DC System Grounding

The ground wire return system is preferred.

1. If a chassis ground is used, then

   1. The ground connection shall be designed and installed to remain corrosion free for the life of the equipment. Ground connection to an electrically conductive chassis or frame shall be mechanically secured to a spot welded stud, or a screw with flat washer, lock-washer and nut (nylock nut is acceptable in lieu of nut and lock washer) or tapped hole. The metal ground connection shall be free of paint and, after assembly, shall be covered with a corrosion resistant film (e.g., liquid tape electrical by Plastic Dip, 3M under body coating, etc.) The use of a toothed lock washer to cut through a coating is not acceptable.

   2. The current carrying capacity of the connection between battery and frame shall be adequate for the anticipated loads.

2. In a frame ground (chassis ground) return system, the maximum current allowed through the frame shall be the manufacturer's recommended limit for the vehicle (e.g., Ford Body Builder maximum is 30 amps). If the current is greater than the manufacturer's recommended limit, then a two wire configuration (one wire for positive and one wire for negative) shall be used. If possible, connections directly to the battery post should be avoided. A buss system is preferred. (Connections directly to the battery are difficult to keep corrosion free.) It is preferred to make this connection at the starter motor relay’s positive terminal, not at the battery’s positive terminal. A separate buss system shall be set up close to the battery. See following drawing "BUSS SYSTEM". (This paragraph does not apply to factory-installed, vehicle starter motors).

1.2.2 Ground Potential

1. Antenna and transmission line terminals shall be at ground potential, except for radio frequency (RF) energy on their external surfaces. Installer shall follow antenna manufacturer's recommendations.
2. All outer metal cases of electrical components shall be at ground potential or covered by an external casing made of insulating material. The external casing shall enclose the original case on all sides except the terminal sides.
3. A point on the electrically conductive chassis or equipment frame shall serve as the common tie point for the power (earth) ground. Installer shall use only those ground (earth) points recommended by the vehicle or equipment manufacturer.

1.2.3 Electrical Items Mounted to Hinged Panels and Doors

Hinges or slides are not considered adequate grounding paths, therefore doors, panels, etc., with hinges or slides shall be grounded by use of a flexible ground strap.

1.2.4 Wire Stripping

There shall be no evidence of burns, abrading, or pinch marks in the insulation that could cause short circuits or leakage. All wire to be stripped of insulation shall have smooth cuts and the wire conductor free of nicks, scrapes or cuts, per Class 2 requirements described in IPC-A620.

1.2.5 Cable Splicing in a Harness

1. An uninterrupted wire is preferable to a spliced wire.
2. Splices in wires inside the cab or inside sealed enclosures shall be spliced with nylon insulated, butt splices. Double crimp type is preferred. It is acceptable to use step down nylon or vinyl insulated butt splices when connecting multiple wires (two in, one out) or wires of different gauge sizes. Also allowed are, nylon insulated, bell or closed end connector type.
3. Splices exposed to the outside environment shall be completely sealed from wet conditions. There are many ways to seal a splice exposed to wet conditions. Butt splices are the preferred splice. Bare metal barrel or nylon insulated, double crimp type, can be sealed with adhesive lined heat shrink tubing (e.g., ES 1000 by Raychem, TES by 3M). There are also special butt connectors that have the adhesive lined heat shrink tubing already installed. Other sealed splices require written approval of Caltrans, Quality Assurance (916-227-9709). Electrical tape is not acceptable as a splice seal for locations outside a cab enclosure.
4. Splices are not acceptable in areas of hard bend or flexing.
5. There shall be no splicing or cutting into the engine or transmission control system wires (e.g., engine run signal, speed, etc.) without prior written approval of Caltrans Quality Assurance (916-227-9709).

1.2.6 Through-Hole Protection

1. Whenever wires are run through holes in partitions, shields, and the like, less than 1/8" thickness, the holes shall be equipped with grommet. Panels 1/8" or more in thickness shall have grommets or shall have the hole edges rounded to a minimum radius 1/32" and abrasion protective covering on wires (e.g., loom).
2. Where wires and cables penetrate an enclosure, or are exposed to the outside environment, insulating weatherproof (IP65) or watertight (IP67) bulkhead fitting shall be used.
3. Wire or other penetrations of a cab shall only be inserted into the cab from below and shall meet the requirements of IP65 or IP67. Cable access or mounting holes through the top or sides of a cab are not acceptable, except with prior written approval from Caltrans Quality Assurance 916-227-9709.

1.2.7 Cable and Wire Support

Adhesive backed tie holders are not acceptable in any application.

1. Cab Exterior:

   Wire and cable shall be properly supported at least every 18" and secured with insulated metal loop clamps to prevent undue stress on the conductors and terminals and undue change in position of the wire or cable during and after subjection of the equipment to specified service conditions.

2. Cab Interior:

   Only insulated metal loop clamps or screw mounted wrapping and tying devices are acceptable.

1.2.8 Cable Ties

Nylon cable ties may be used only for bundling of multiple conductor cables and wiring. When used, nylon cable ties shall be trimmed flush. Cable ties shall not be used as a means of support, except for interior, under dash locations where loop clamps cannot be installed. If used outdoors, then black UV stabilized nylon cable ties shall be used. It is permissible to use cable ties to tie wires to existing wire runs on rigid frame members. Cable ties shall be of adequate size to support the harness load.

1.2.9 Wire Bend Radius

The bend radius of wire and cable shall not be less than five (5) times the cable or wire diameter to avoid establishing a permanent set in the cable.

1.2.10 Sleeving

1. Where corrugated loom is employed, provisions shall be made for the removal of any wire that may become faulty. (e.g., a split in the loom).
2. Flexible plastic sleeving (e.g., loom) for use in the cab shall be black polyethylene (80 °C) minimum and for under hood or under body shall be black nylon (120 ° C) minimum. All wire exposed to the outside environment, road damage, splashing, spray or other wet conditions shall be run in loom.
3. Flexible plastic sleeving shall be used on cables subject to flexing, such as panel door cables. The sleeving shall be secured under cable clamps at each end, and the cable shall be formed and secured so that the cable shall not be subject to abrasion in its normal flexing motion. In cases where abrasion cannot be avoided, additional protection (e.g., thicker walled loom) shall be provided. Wiring to parts on a hinged door shall be in a single cable if possible, arranged to flex without being damaged when the door is opened and closed.

1.2.11 Slack

Wires and cables shall be as short as practicable, except that sufficient slack shall be provided to:

1. Prevent undue stress on cable , wires and connections, including connections to resiliently supported parts;
2. Enable parts to be removed and replaced during servicing without disconnecting other parts;
3. Facilitate field repair of broken or cut wires;
4. Units which are difficult to connect when mounted, shall be capable of movement to a more convenient position for connecting and disconnecting cables.

1.2.12 Wire Routing

All wire routing shall conform to the following:

1. Shall be shielded from or routed away from heat sources.
2. Shall be protected or routed away from environmental exposure.
3. Shall not be placed under tension.
4. Shall be free and clear of any moving parts.
5. Wiring harness covering shall protect the harness in the operating environment and provide protection from road damage.
6. All mateable connectors shall be accessible during maintenance.
7. Cable and harnesses shall be routed along rigid sections of the cab or chassis where possible.
8. Wires shall be protected or secured away from sharp edges, including screw threads and from any other feature that might cut the insulation.
9. Wiring to components in exposed locations shall have a drip loop to prevent moisture from running up the wire.
10. The harness and cable ties, straps, etc., shall be neat in appearance, uniformly applied, and positioned to retain critical form factors and breakout locations. The containment means (lacing, ties, tie-down straps, etc.) shall not cause the wire or cable insulation to deform so that performance characteristics are adversely affected.

1.2.13 Hook Up Wire and Battery Cable for DC

1. Hook up wire for cab interior locations (passenger compartment), shall be automotive primary wire Type GPT or HDT meeting SAE J1128 80 ° C and shall be routed away from high temperature areas.
2. Hook up wire for under hood and under body locations, shall be automotive primary wire Type SXL, GXL, TLX 125 °C meeting SAE J1128. If SAE wire is used, an invoice or other certificate of compliance from the wire supplier or wire manufacturer shall be provided.
3. Minimum accepted wire for battery type cable shall conform to SAE J1127, Type SGX or STX 125 °C and Type SGT 105 °C .
4. Also allowed for hook up wire for interior or exterior are:
   • UL 1015 (also known as 1015/1230) 18 gauge to 10 gauge, stranded conductors and tinned, 105 °C
   • UL 1028/1231 - 1283/1231 for 8 gauge to 2 gauge stranded conductors and tinned,105 °C, rated 600V
   • Marine rated primary wire, meeting UL 1426 for boat cable, stranded conductors and tinned, 105°C, 600V, type 3.
5. Applications in high temperature areas shall use wire designed for high temperature, UL 3271, UL 3284 or UL 3289.
6. Electrical cable size shall be no smaller than 18 gauge (AWG). Electronics cable size shall be no smaller than 22 gauge (AWG).
7. Cables with fine stranding shall be used in areas subject to flex and vibration ( e.g., Type 3 marine cable or better).
8. All conductors shall be stranded copper wire. If tinned, bonded tinned, bunched tinned or tinned overcoat is not acceptable.

1.2.14 DC Conductor Sizes

Any voltage drop not specified shall not lower the terminal voltage at the point of consumption to below 95% of battery voltage.

1.2.15 DC Wiring Color Codes

NOTE - It is desirable for the wire of any one circuit to be of uniform color code throughout the circuit regardless of the number of connections. A circuit is assumed to be continuous until it can be interrupted by a relay or switch contacts, or when it reaches a load (such as bulbs, motors, etc.). Fusible links may differ in color from the circuits they are protecting, as it could be advantageous to identify fusible link wire gauge size by insulation color.

Caltrans standard wire color and size are specified by type of use in the following "Wire Identification" table. (Note: This is the minimum wire gauge size; actual size may differ due to circuit length. Refer to wire gauge selection chart)

1.2.16 Seven-Pin Trailer Connector

Caltrans uses the SAE J560 standard plug connector for truck-trailer connections, except that the wiring configuration is changed per the following sketch and table (e.g., Cole Hersee 7 Pole Socket #12310 w/Boot #81356 and Plug #12311).

1.3 AC Wiring 120 or 120/240 Volt

If there is a difference between this Caltrans Division of Equipment Electric Standard and the National Electric Code (NEC), then the Caltrans Division of Equipment Electric Standard takes precedence.

1.3.1 AC Hook Up Wire and Cable

1. One of the following hook up wires shall be used for AC applications:
   • UL Type THHN 90 °C, stranded conductor
   • UL 1015 (also known as 1015/1230),18 gauge to10 gauge, stranded conductors, tinned, 105 °C, rated 600 V
   • UL 1028/1231 - 1283/1232 for 8 gauge to 2 gauge, stranded conductors, tinned, 105 °C, rated 600 V
   • Marine rated hook up wire, meeting UL 1426 for boat cable, stranded conductors and tinned, 105 °C, 600 V, Type 3
2. Applications in high temperature areas shall use wire designed for high temperature, UL 3271 or UL 3289.
3. AC wire colors shall conform to the following code:

1.3.2 AC System Grounding

1. All AC equipment shall be grounded. Prior written approval is required for use of double insulated devices. Call Caltrans Division of Equipment, Quality Assurance Branch at 916-227-9709.
2. Grounding conductors shall be green insulated wire or green wire with yellow stripe.
3. In a grounded distribution system, there shall be only one connection to ground, regardless of the number of power sources. The ground wire shall be 8 gauge and connected at the main engine battery ground (earth) point. Installer shall use only those ground (earth) points recommended by the vehicle or equipment manufacturer.
4. Each receptacle outlet shall have a grounding-pole and a grounding-conductor in the portable cord.
5. Metal conduit may not be used to ground electrical equipment or systems. A separate wire shall be used.
6. Grounding shall conform to National Electric Code (NEC) 250-6 (Portable and Vehicle Mounted Generators.)
7. All metal parts, conduit, enclosures, frame, etc., shall be bonded to the grounding terminals of the switchboard and/or distribution panels.

1.3.3 Material and Equipment

All parts used on AC systems shall be UL listed or recognized.

1.3.4 AC System Cable and Wiring Requirements

AC system and wiring shall conform to the following:

1. Conduit: All AC hookup wire shall be run in metal conduit. When exposed to the outside environment, wires shall be run in liquid-tight, 105 °C, jacketed, flexible steel (e.g., Type ALTA by Electri-Flex) or EMT conduit. (e.g., UL Std. 797 ANSI C-80.3). If EMT conduit is used, it shall only be used on rigid sections. It is acceptable to use non-jacketed flexible steel conduit (e.g., Type BR by Electri-Flex) in dry locations.
2. Conduit Fittings: Liquid-tight conduit fittings shall be insulated, steel/iron type (e.g., RACO # 35xx). For EMT conduit, fittings shall be insulated steel/iron compression type (e.g., RACO #29xx). Insulated set screw type connectors are acceptable only for short conduit runs in dry locations. (e.g., RACO 21XX). For non-jacketed, flexible, conduit, fittings shall be insulated steel/iron squeeze type (e.g., RACO #33xx). Die cast zinc conduit fittings are not allowed in any application.
3. Boxes: Boxes shall be weather proof aluminum, threaded hole type with appropriate covers. Steel outlet or handy boxes are not acceptable. (e.g., Bell Weatherproof #53xx).
4. Wire termination: AC devices that come with pigtails, shall be terminated with nylon insulated double crimp type butt splice or nylon insulated bell or closed end crimp splices. Wire nuts are not acceptable for AC wire termination. For outlets, switches or other AC devices wires shall be inserted through the rear and attached with screw clamps or insulated ring terminal to screws .
5. Wiring shall have stranded copper conductors with sufficient current carrying capacity. Solid core wire is not acceptable. Conduit shall be installed with metal supports not more than 18 inches apart.
6. Boxes shall be mounted per National Electric Code (NEC) 370 (Outlet, Device, Pull and Junction Boxes, Conduit Bodies and Fittings)
7. Also reference Sections 1.2.3, 1.2.4, 1.2.6, 1.2.7, 1.2.11, and 1.2.12.

1.3.5 Shore Power

Equipment with an electrical system operating at single phase 120/240 volt ac, which is provided with a means to connect to shore power, shall meet the following:

1. A shore power connection box or weatherproof (IP 65) surface receptacle shall be permanently installed at a convenient location. The ac power inlet receptacle shall be a locking male type. (e.g. ParkPower by Marinco).
2. A label shall be placed next to the shore power connection stating the voltage, frequency and current rating of the connection. (e.g. "120 V AC, 60 Hz, 30 amp")
3. An outside rated weatherproof (IP 65) shore power cable, 25 feet minimum length, connecting the shore power connection box or receptacle to the switchboard or main distribution panel shall be provided. (e.g., ParkPower by Marinco)
4. A circuit breaker shall be provided at the switchboard or main distribution panel for shore power connection
5. The circuit breaker, required by Section 1.3.5.C(above) shall be interlocked with the vehicle’s power sources so that shore power and the vehicle’s power sources may not be operated simultaneously. (e.g., Carling Tech. C Series Power Selector or a manual or automatic transfer switch)
6. The circuit breaker used shall also open all ungrounded (hot) conductors. A circuit breaker may be installed in the grounded neutral (white) wire as long as it opens all current carrying conductors in the circuit.
7. The shore power green ground wire shall have no switches or circuit breakers installed and shall be connected to the ground point at the Switchboard / Distribution Panel.

1.3.6 AC Switchboard & Distribution Panels

1. Each distribution panel or switchboard shall be in a location as dry as practicable, accessible, adequately ventilated, and protected from falling debris and dripping or splashing water.
2. Each distribution panel or switchboard shall be totally enclosed and of the dead-front type.
3. Each distribution panel or switchboard accessible from the rear shall be constructed to prevent a person’s accidental contact with energized parts.
4. Each uninsulated current-carrying part shall be mounted on noncombustible, nonabsorbent, high-dielectric insulating material.
5. Each distribution panel or switchboard shall have a grounding terminal block with enough terminals for all AC chassis grounding.
6. Each distribution panel or switchboard shall have a separate neutral (white) wire terminal block with enough terminals for all neutral wiring. It shall be insulated from the equipment AC chassis grounding.
7. Equipment mounted on a hinged door of an enclosure shall be constructed or shielded so that no person shall come into accidental contact with energized parts of the door-mounted equipment when the door is open and the circuit energized.
8. The door of each panelboard enclosure that is accessible to the public shall have a locking device.
9. Each panelboard switching unit shall be labeled
10. Each switch board or distribution panel shall have a volt meter to indicate the main incoming voltage. (Welder generators do not apply).
11. Appropriate warning labels shall be placed on the outside of switch boards and distribution panels. (e.g. Warning/danger 120/240 VAC).
12. Each panelboard shall have:
    1. A circuit directory label
    2. The circuit designation of each circuit.
    3. The rating of the overcurrent protective device for each circuit.

1.3.7 AC Receptacles & Switches

1. All receptacles shall be protected by a Type A ground fault circuit interrupter, hospital grade or better. (e.g., Leviton Smartlock GFCI, hospital grade, 15A-125v [20A-125v] with light, 8598-HGW [8898-HGW], or equivalent).
2. Manufacturer's recommendations for hooking up wires to plugs, receptacles, switches and devices shall be followed.
3. AC receptacles shall be the grounding type and shall be installed per National Electric Code (NEC) 210-7 (Receptacles and Cord Conductors).
4. AC receptacles and plugs shall not be used for DC nor shall DC receptacles and plugs be used for AC.
5. All AC outlets, switches etc., shall be specification grade or better (e.g., 5262A, 5362A and 1201-2, 1221-2 by Leviton).
6. All receptacles exposed to the outside environment shall be weatherproof and installed per National Electric Code (NEC) 210-7 (Receptacles and Cord Conductors).
7. Receptacles shall not be installed with the face pointing up.

1.3.8 AC Testing

1. Dielectric or Insulation Test: The 120 V AC system shall be tested for breakdown of the wire insulation. All switches shall be closed, between current carrying conductors including neutral and vehicle ground. The AC system shall withstand this test without breakdown.
2. Continuity Test: This test is to verify that all metal parts are bonded to ground.
3. Polarity Test: This test is to verify that all connections have been made correctly.