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Solar PV Bonding & EGC Size Calculator (CEC / CSA C22.1)

Size the bonding conductor and module-frame jumper for a Canadian residential PV array per CSA C22.1:2024 Table 16. Free copper / aluminum lookup.

Solar PV Bonding Conductor Size Calculator

Minimum bonding conductor
10 AWG
Code reference: CSA C22.1 Tab. 16
Lug torque
35 in-lb (4 N·m)
Module frame bonding jumper: 10 AWG
Notes: CSA C22.1 Table 16 — bonding conductor sized by ampacity. Use CSA-certified bonding lugs and stainless toothed washers.

How to use this calculator

Enter the ampere rating of the overcurrent device protecting the circuit, select copper or aluminum, and the calculator returns the minimum bonding conductor size per CSA C22.1:2024 Table 16. The same value applies to the module-frame bonding jumper.

Inputs:

  1. DC overcurrent device rating (A) — fuse or breaker protecting the circuit. For a typical 600 V residential string protected by a touch-safe DC fuse in the combiner: 15 A or 20 A. For the inverter AC output, 60 A on a 7.6 kW string inverter.
  2. Bonding conductor material — copper for nearly every Canadian PV install. Aluminum permitted at 6 AWG and larger for long ground-mount runs.

How the math works (CEC Table 16)

CSA C22.1:2024 Table 16 sizes the bonding conductor from the OCPD rating:

OCPD ≤ 15 A      → 14 AWG Cu / 12 AWG Al
OCPD ≤ 20 A      → 12 AWG Cu / 10 AWG Al
OCPD ≤ 60 A      → 10 AWG Cu /  8 AWG Al
OCPD ≤ 100 A     →  8 AWG Cu /  6 AWG Al
OCPD ≤ 200 A     →  6 AWG Cu /  4 AWG Al
OCPD ≤ 300 A     →  4 AWG Cu /  2 AWG Al
OCPD ≤ 400 A     →  3 AWG Cu /  1 AWG Al
OCPD ≤ 600 A     →  1 AWG Cu / 2/0 AWG Al

The values match US NEC Table 250.122 — both codes were harmonized in the 2018 cycle.

Worked example. A 7.6 kW Ontario rooftop array uses a string inverter with two MPPT inputs at 12 A Imp each, protected by a 20 A touch-safe fuse on each MPPT. Table 16 gives the DC-side bonding conductor as 12 AWG Cu. The inverter AC output is a 40 A back-fed breaker at the main panel; Table 16 gives 10 AWG Cu for the AC-side bonding conductor.

If the array is on a detached garage and the ungrounded AC conductors are upsized from 8 AWG to 6 AWG for VD on a 40 m run, Rule 10-814(b) requires the bonding conductor to scale by the same circular-mil ratio (26,240 / 16,510 = 1.59 × 10,380 cmil = 16,500 cmil — round up to 8 AWG Cu).

CEC Section 64 — PV-specific bonding

CSA C22.1 Section 64 covers PV systems. The bonding clauses:

  • 64-066 — bonding requirements reference Section 10 (general bonding).
  • 64-068 — bonding conductor sized per Rule 10-806 / Table 16.
  • 64-070 — module-frame bonding hardware must be CSA-certified for the specific frame profile (UL/CSA 2703 listed).
  • 64-216 — DC-side ground-fault protection (most modern non-isolating inverters include this internally).

The 2024 cycle of CSA C22.1 is the current document for new installations in most provinces (Ontario, BC, Alberta on 2024 cycle as of 2026; Quebec on a slightly modified version under Hydro-Québec rules).

Module-frame bonding hardware (CSA-listed)

Canadian installers use the same three approaches as US installers, with CSA-certified versions:

  1. WEEB-9.5 or similar toothed washer — Wiley Electronics WEEB-9.5 is CSA-listed under UL/CSA 2703. Cheapest at CAD 0.60-1.00 per module wholesale. Compatibility matrix on Canadian Solar, Silfab, REC, Heliene, JinkoSolar manufacturer sites.
  2. Integrated grounding rail — Unirac SolarMount, IronRidge XR1000, K2 SingleRail, EcoFasten Rock-It. All CSA-certified. The rail provides UL/CSA 2703 listed grounding pins so no extra hardware per module.
  3. Discrete M6 / 1/4-20 lugs with bare 6 AWG copper jumper — ILSCO GBL-4DBT and Burndy BGBL are CSA-listed. Older approach still acceptable but adds 30-60 minutes labour per array vs WEEB clips.

Silfab Solar (Canadian-manufactured) and Heliene publish compatibility lists for their modules on each major rack brand.

When voltage drop forces a bonding conductor upsize

CEC Rule 10-814(b) — if circuit conductors are increased in size for VD, the bonding conductor must be increased by the same circular-mil ratio. This is the same rule as US NEC 250.122(B) and trips up most DIY PV permit applications.

Rule of thumb: if you upsize the ungrounded conductors by one AWG (1.26× area ratio), upsize the bonding conductor by one AWG too. The arithmetic always rounds up to the next standard AWG size at one full step.

Use the solar panel voltage calculator on this site to check VD on long rooftop or ground-mount runs.

ESA / TSSA / provincial inspection findings

The most-common bonding faults flagged by Ontario ESA, BC Technical Safety BC, and Alberta ABSA inspections:

  1. Bonding conductor not upsized after circuit conductor was upsized for VD (Rule 10-814(b)).
  2. Module-frame bonding hardware not CSA-certified for the specific frame profile.
  3. Discontinuous bonding at a metallic raceway-to-non-metallic transition (no bonding bushing under Rule 10-616).
  4. Aluminum bonding conductor terminated in a copper-only lug (Rule 12-118 / 110.14 in NEC parlance).
  5. M6 earth lug installed without a toothed washer biting the anodized frame — fails continuity test at > 5 Ω.

A pre-energisation continuity test from the farthest module frame to the service neutral bar should read ≤ 1.0 Ω. Ontario ESA inspections require this measurement to be documented on the PV permit final inspection report.

Cold-climate considerations

Canadian PV grounding has two extra concerns beyond US practice:

  • Frost heave at ground-mount arrays — bonding conductor across frost-line transitions must allow for 100-150 mm of vertical movement without strain. Use a service loop and PVC-jacketed THWN-2 (or RW90 in Quebec) instead of bare conductor across the frost line.
  • Ice damming around rooftop bonding lugs — exposed M6 lugs collect ice in spring melt cycles, accelerating galvanic corrosion. Most Canadian installers prefer integrated grounding pins (Unirac, IronRidge) over discrete lugs for this reason.

The continuity test result should be re-measured after the first full winter — a > 50% increase in resistance indicates corrosion at the bonding interface and the affected hardware should be replaced.

Sources

Frequently asked questions

What size bonding conductor do I need for a residential PV array in Canada?
Per CSA C22.1:2024 (Canadian Electrical Code) Table 16, the bonding conductor is sized from the ampere rating of the overcurrent device protecting the circuit. For a typical residential PV string protected by a 15 A or 20 A fuse the bonding conductor is 14 AWG copper or 12 AWG copper respectively. For a 60 A inverter output the bonding conductor is 10 AWG copper. Section 64 of the CEC (PV systems) references Table 16 directly — no separate PV-specific bonding table.
Does the bonding conductor need to be upsized for voltage drop on long PV runs?
CEC Rule 10-814(b) imposes the same upsize rule as the US NEC: if the ungrounded circuit conductors are increased for voltage-drop reasons, the bonding conductor must be upsized proportionally by circular-mil area. On a long roof-to-inverter run where the ungrounded conductors move from 10 AWG to 8 AWG, the bonding conductor follows from 10 AWG to 8 AWG. Most ESA / TSSA inspectors check this on PV permit inspections.
How do I bond solar panel frames in Canada?
Use a CSA-certified bonding device listed for the specific module frame. Most installers use WEEB-style toothed washers (Wiley Electronics WEEB-9.5 has CSA listing under UL/CSA 2703), Unirac SolarMount or IronRidge XR1000 with integrated grounding pins (both CSA-certified), or ILSCO GBL stainless earth lugs with bare 6 AWG copper jumper. Whatever you pick, it must appear on the CSA-issued listing certificate for the rail-and-module combination.
Do I need a separate ground rod at the PV array in Canada?
CEC Rule 10-700 plus Section 64 follow the same approach as the 2017+ US NEC — no separate auxiliary grounding electrode at the array. The bonding conductor runs back to the existing service grounding electrode system at the main panel. The exception is detached structures and ground-mount arrays > 30 m from the main service, which fall under Rule 10-204 sub-panel grounding (separate electrode bonded back to service via a GEC).
What is the difference between bonding and grounding in Canadian PV?
The CEC uses 'bonding' for what the US NEC calls 'equipment grounding' — connecting all exposed conductive parts together back to the service neutral / ground at the main panel via the bonding conductor. 'Grounding' in the CEC refers specifically to the grounding electrode and the grounding electrode conductor (the link to the building's grounding system). Section 10 covers both; Section 64-068 references Section 10 for all PV bonding and grounding requirements.
Can I use aluminum bonding conductors for a PV system?
Yes for sizes 6 AWG and larger per CEC Rule 10-816. Aluminum bonding conductors must be one AWG size larger than the equivalent copper from Table 16 — if Table 16 calls for 10 AWG Cu, you'd use 8 AWG Al. Aluminum is mostly used for long ground-mount runs (e.g. detached cabin systems) where the cost savings on a 4/0 AWG or larger run justify the larger trench. Outdoor copper-aluminum transitions require AL9CU-rated lugs (e.g. ILSCO TPB-1).

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