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CSA C68.9-09 (2018) Technical Overview: Concentric Neutral Power Cables for Distribution Systems
Key Requirements and Compliance for Medium-Voltage Cable Applications
Scope of CSA C68.9-09 (2018)
CSA C68.9-09 (R2018) – Concentric Neutral Power Cables for Distribution Systems – specifies the construction, testing, and performance requirements for single-conductor, concentric neutral cables rated 5 kV to 46 kV. These cables are intended for use in underground distribution networks, direct burial, or installation in ducts where continuous metallic neutral protection is required. The standard covers copper or aluminum conductors with cross-linked polyethylene (XLPE) insulation, a semiconducting insulation shield, and a concentric neutral of bare copper wires applied helically over the insulation shield.
The standard was originally published in 2009 and reaffirmed in 2018 without technical changes, confirming its continued relevance in the Canadian electrical utility industry. It aligns with industry practices for reliability, safety, and environmental resistance, and it references related standards such as CSA C22.2 No. 0 and CAN/CSA-C68.5.
Technical Requirements
Conductor and Insulation
Conductors must meet the requirements of ASTM B3 (copper) or ASTM B230/B231 (aluminum) and be stranded compact or compressed round. The minimum conductor size is 2 AWG copper or 1/0 AWG aluminum. Insulation thickness is based on voltage class and is listed in Table 1. The insulation must be a tree-retardant XLPE compound that passes the long-term water treeing test (60 Hz, 5 kV/mm for 180 days).
Concentric Neutral
The concentric neutral consists of bare copper wires applied helically with a nominal lay length between 10 and 16 times the diameter over the insulation shield. The neutral wire size and number are selected based on the required ampacity and fault-current capacity. For a given conductor size, the standard specifies minimum neutral sizes as shown in Table 2.
| Voltage Class (kV) | Conductor Size (AWG or kcmil) | Insulation Thickness (mm) |
|---|---|---|
| 5 | 2 – 1000 | 2.29 |
| 8 | 2 – 1000 | 2.79 |
| 15 | 2 – 1000 | 3.56 |
| 25 | 1/0 – 1000 | 4.45 |
| 35 | 1/0 – 1000 | 5.59 |
| Conductor Size (AWG/kcmil) | Number of Neutral Wires | Neutral Wire Size (AWG) |
|---|---|---|
| 2 | 6 | 14 |
| 1/0 | 10 | 14 |
| 350 | 16 | 12 |
| 500 | 20 | 12 |
| 750 | 30 | 12 |
Implementation Highlights
Installation Considerations – Cables conforming to CSA C68.9-09 can be installed in wet or dry locations, in duct or direct burial. The standard requires that the overall cable jacket (if any) be a sunlight-resistant PVC or polyethylene. For direct burial, a jacket is mandatory. The concentric neutral provides an effective grounding path, but bonding and grounding practices must follow the Canadian Electrical Code (CE Code) Part I.
Tip: When splicing or terminating, ensure that the neutral wires are handled carefully to preserve the lay length and avoid damage to the semiconducting shield. Use factory‑approved splice kits rated for the voltage class.
Warning: Concentric neutral cables are not approved for use as service entrance conductors unless a fully rated conductor is provided inside the cable. Verify local utility requirements before installation.
Testing Requirements
Each cable length must withstand a high‑voltage test after manufacture: for 5–15 kV cables, 200 % of rated voltage rms (at 60 Hz) for 5 minutes. Additional tests include partial discharge measurement (less than 5 pC at 150 % of rated phase‑to‑ground voltage) and a DC withstand test for cable accessories. Routine tests are performed per the standard’s clauses; type tests include aging, water treeing, and cold bend tests.
Compliance Note: Recent adoption of the 2018 reaffirmation by provincial regulators means that cables bearing the CSA mark with year “C68.9-09 (R2018)” are accepted across Canada. Always verify the marking on the cable jacket.
Compliance Notes
Manufacturers must document compliance with CSA C68.9-09 (2018) through a conformity assessment program that includes periodic audit testing by an accredited certification body (e.g., CSA Group). The standard also requires that the product be marked with the CSA monogram and the standard number. Imported cables must be retested or certified to the same requirements to be considered compliant.
Important updates since the original 2009 edition include clarifications on the neutral lay length measurement and tighter tolerances for insulation eccentricity (maximum 15 % variation). These changes were incorporated in the 2018 reaffirmation. Users should refer to the latest edition of the Canadian Electrical Code for installation conditions, especially where neutral sizing might be influenced by fault current requirements.
Critical: Non‑compliance can lead to premature cable failure, conductor corrosion, or neutral wire rupture during fault conditions. Contractors and utilities must only procure cables with valid, current certification to CSA C68.9-09 (R2018).
For further guidance, consult CSA Technical Committee reports or contact the utility’s standards department.
Frequently Asked Questions
Q: What is the difference between CSA C68.9-09 and CSA C68.5?
A: CSA C68.5 covers general power cables up to 5 kV, while C68.9 is specifically for medium‑voltage (5–46 kV) concentric neutral cables for distribution. C68.9 includes additional requirements for the neutral design and high‑voltage testing.
A: CSA C68.5 covers general power cables up to 5 kV, while C68.9 is specifically for medium‑voltage (5–46 kV) concentric neutral cables for distribution. C68.9 includes additional requirements for the neutral design and high‑voltage testing.
Q: Does the 2018 reaffirmation change any technical requirements?
A: No, the reaffirmation confirms the 2009 version without technical changes. However, administrative updates and editorial clarifications were made to align with current referencing standards.
A: No, the reaffirmation confirms the 2009 version without technical changes. However, administrative updates and editorial clarifications were made to align with current referencing standards.
Q: Can CSA C68.9 cables be used in riser applications?
A: The standard does not specifically address riser cable installations. When used in vertical shafts, the cable must be secured to prevent excessive stress on the neutral wires. Consult the manufacturer’s recommendations and applicable building codes.
A: The standard does not specifically address riser cable installations. When used in vertical shafts, the cable must be secured to prevent excessive stress on the neutral wires. Consult the manufacturer’s recommendations and applicable building codes.
Q: What voltage system is assumed for the cable ratings?
A: Ratings are for three‑phase, effectively grounded systems. For ungrounded systems, the use factor (1.73) may require a higher voltage class cable; refer to the standard’s Annex A for guidance.
A: Ratings are for three‑phase, effectively grounded systems. For ungrounded systems, the use factor (1.73) may require a higher voltage class cable; refer to the standard’s Annex A for guidance.
© 2026 – International Standards Review. This article is for informational purposes and does not substitute the official standard document.