18.1 Cable Installation & Termination Requirements
Key Takeaways
- EPC 35 is a critical capability: install and terminate a variety of cables in a wide range of applications to AS/NZS 3000
- Cables must be supported, protected against mechanical damage, and installed so they can be drawn in without stretching, kinking or stripping insulation
- Where a cable passes through a fire-rated wall or floor, the fire-rating integrity of that element must be reinstated with a tested penetration system
- A termination must be mechanically sound, electrically continuous, of low resistance, and made with the correct terminal for the conductor material and size
- TPS, circular TPS, steel wire armoured, fire-rated and flexible cables each have distinct support, bending, gland and termination requirements
Cable Installation & Termination Requirements
Quick Answer: Route cables where they are protected, support them at the required intervals, do not exceed the minimum bending radius, and reinstate the fire rating of every element you penetrate. Every termination must be mechanically sound, electrically continuous and low resistance, made with the right terminal, correctly torqued, and with the correct amount of insulation removed.
Why Installation Practice Is a Critical Capability
Calculation gets the right cable on paper. EPC 35 is about whether that cable survives fifty years in a wall. Assessors watch installation and termination technique closely on the practical because poor workmanship here produces exactly the defects that later cause fires, shocks and intermittent faults.
Typical Cable Routes Through Buildings
| Location | Requirement to state |
|---|---|
| Wall cavities | Run in permitted zones so later fixings are less likely to strike the cable; protect where the cable can be penetrated |
| Through studs and noggings | Hole centred in the member, with mechanical protection where the required cover cannot be achieved |
| Ceiling spaces | Support and route clear of walkways, storage and downlight heat; never in contact with thermal insulation unless the derating has been applied |
| Under floors | Supported clear of the ground; protected where accessible |
| Buried in walls / concrete | Enclosed in conduit or otherwise protected, with route identification |
| Fire-rated elements | Penetration sealed with a tested system that restores the rating |
Cables must not be run where they will be damaged by moving parts, heat, corrosive substances or vermin unless the wiring system is suitable for those influences.
Support, Fixing and Drawing In
- Fix at intervals appropriate to the cable type and orientation — vertical runs need closer support than horizontal runs on a surface.
- Do not exceed the minimum bending radius; a kinked conductor has damaged insulation and reduced cross-section at the very point of stress.
- Draw in without excessive tension. Use a draw wire, cable lubricant where permitted and a swivel to prevent twisting. Dragging a cable over a sharp conduit end strips insulation invisibly.
- Do not fill conduits beyond the permitted space factor — overfilled conduit means cables that cannot be withdrawn, are mechanically stressed, and are thermally derated.
- Provide draw-in points so long or multiply-bent conduit runs remain workable.
- Support must not rely on the accessory: a cable must be fixed close enough to its outlet that the terminals carry no mechanical load.
Wiring Accessories
Accessories must be suited to the location and the cable:
- Correct IP rating for damp, outdoor and wash-down positions.
- Mounting blocks and boxes that provide adequate depth so conductors are not crushed when the accessory is fitted.
- Cord grips on flexible connections so tension is taken by the sheath, not the terminals.
- Correct entry method so the cable sheath enters the enclosure and the individual insulated cores are not exposed outside it.
Cable Types and Their Handling
| Cable | Typical use | Handling notes |
|---|---|---|
| Flat TPS | Domestic and light commercial fixed wiring | Keep the sheath intact into the accessory; do not bend tighter than the radius |
| Circular TPS | Where a round profile suits conduit or glands | Bedding may need removal carefully to avoid nicking cores |
| Steel wire armoured (SWA) | Underground, exposed and industrial | Requires a correct gland; the armour may serve as an earth path only if the design says so, and the gland must be bonded |
| Fire-rated cable | Circuits that must keep operating during a fire | Support system must be non-combustible; standard plastic clips will fail and drop the cable |
| Flexible cords | Appliance and equipment connection | Not a substitute for fixed wiring; anchor and protect against flexing at the entry |
| Aerial and underground cables | See Section 18.3 | Different support, depth and clearance rules |
Fire-rated cable is a common trap: fixing a fire-rated cable with ordinary plastic saddles defeats the entire purpose, because the saddles melt and the cable falls before its rated survival time.
Maintaining Fire-Rating Integrity
When a cable passes through a fire-rated wall, floor or ceiling, the penetration must be sealed so the element retains its fire resistance level. Points to state:
- Use a tested and certified penetration system suited to the cable type, the element construction and the rating required.
- Follow the tested detail — annulus size, sealant depth and any collar or wrap are all part of the tested system.
- Record and label the penetration where the building requires it.
- Do not simply pack a hole with expanding foam or generic sealant; that is not a rated system and is a defect.
Making a Sound Termination
A compliant termination is:
- Mechanically sound — will not pull out under reasonable force, with no strand damage.
- Electrically continuous and low resistance — full conductor cross-section clamped, no insulation under the screw, no oxide layer on aluminium.
- Made with the correct terminal for the conductor material, size and number of conductors, and torqued to the manufacturer's specification.
- Correctly stripped — enough insulation removed to seat fully in the terminal, and no more. Copper visible beyond a terminal is a shock and short-circuit risk.
- Correctly identified — sleeved or marked where the core colour would otherwise be ambiguous.
Additional discipline:
- Do not mix conductor materials in a terminal not designed for it; a copper-aluminium joint corrodes and rises in resistance.
- Ferrules or bootlace crimps on fine-stranded conductors prevent strand spread under a screw terminal.
- One conductor per terminal unless the terminal is designed and rated for more.
- Re-torque after initial thermal cycling on larger connections where the manufacturer specifies it.
The physics behind all of this is Section 16.1: a poor termination is a series resistance, and P = I²R turns it into a heat source inside a wall cavity or a switchboard.
A fire-rated cable is installed to maintain supply to a fire pump during a fire. Which installation error would most directly defeat its purpose?
A cable passes through a fire-rated wall. What must be done to the penetration?
Which of these describes a compliant screw termination?
Why must a cable be fixed close to the accessory it terminates into?