Earthing Code Comparison

Earthing and Grounding: How Three Codes Solve the Same Problem Differently

PEC, AS/NZS, and the NEC all protect against the same fault hazard, but the terminology, systems, and sizing tables are not interchangeable.

Every electrical code exists partly to solve the same core problem: when a live conductor faults to an exposed metal part, the protective system needs to clear that fault fast enough to prevent electrocution or fire. PEC, AS/NZS, and the NEC each approach this with their own terminology, system architecture, and reference tables.

Terminology First

Concept	PEC / general Philippine usage	AS/NZS	NEC
The protective conductor connecting equipment to earth	Earthing conductor	Earthing conductor / earth continuity conductor	Equipment grounding conductor
The conductor to the physical earth electrode	Earth electrode conductor	Earthing conductor to the electrode	Grounding electrode conductor (GEC)
The underlying safety system	Similar TN-based concepts	Multiple Earthed Neutral (MEN) — a TN-C-S variant	Grounded system, per Article 250

"Earthing" and "grounding" refer to the same underlying concept — the terminology split is largely a British-English-derived vs. American-English-derived convention, not a difference in electrical principle.

What's Structurally Similar

All three specify minimum protective conductor sizes via a lookup table keyed to the associated active/phase/service conductor's size — not a flat ratio
All three require bonding of exposed metal parts, mounting structures, and equipment enclosures to the protective earthing system
All three have specific, separate rules for PV/solar installations layered on top of the general earthing requirements — see the dedicated PV earthing considerations in the AS/NZS MEN article and NEC Article 690 article

What Genuinely Differs

The exact sizing tables are independently derived and don't produce matching results for the same active conductor size. The NEC's Table 250.66, notably, splits into separate copper and aluminum columns with different breakpoints — a structural detail that doesn't have a direct one-to-one equivalent presentation in PEC or AS/NZS earthing tables.

The One Universal Rule Worth Repeating

Across every code, the protective earth/ground conductor typically shows no symptom at all if it's undersized — until the day an actual fault occurs and it matters most. Never estimate this size by eye; look it up from the applicable table for the applicable code, every time.

Look up the correct size for your active/service conductor under any of the three codes in the OhmWorks Earthing and Grounding calculators.

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