IEC 81346 vs NFPA 79: Which Standard Should Your Electrical Project Follow?
A clear, practical comparison of IEC 81346 and NFPA 79 electrical standards — covering reference designations, wire colors, enclosure ratings, and how to choose the right standard for your market.
IEC 81346 vs NFPA 79: Which Standard Should Your Electrical Project Follow?
One of the most common questions we receive from clients — especially those working across international markets — is this:
“Should we design to IEC 81346 or NFPA 79? What is the actual difference, and how do we choose?”
It is a genuinely important question because the answer affects every aspect of your project: how devices are labelled, how documents are structured, how BOMs are organized, and critically — whether your panel will pass inspection in the country where it is installed.
This article gives you a clear, practical comparison of both standards so you can make an informed decision for your next project.
Overview: What Are These Standards?
IEC 81346 — Reference Designation System for Industrial Systems
Full name: IEC 81346 “Industrial Systems, Installations and Equipment, and Industrial Products – Structuring Principles and Reference Designations”
- Published by: International Electrotechnical Commission (IEC)
- Applies to: Europe, Asia, Middle East, Australia, and most of the world outside North America
- Scope: A systematic method of assigning reference designations to components within any industrial system, based on the function of the device rather than just its physical location
IEC 81346 replaced the older IEC 61346 standard and introduced a cleaner, more hierarchical system of designation.
NFPA 79 — Electrical Standard for Industrial Machinery
Full name: NFPA 79 “Electrical Standard for Industrial Machinery”
- Published by: National Fire Protection Association (NFPA)
- Applies to: United States (primary), Canada (in conjunction with CSA), and markets that sell machinery into the US
- Scope: Covers the electrical/electronic equipment, apparatus, or systems of industrial machines, with specific requirements for wiring, enclosures, devices, and documentation
NFPA 79 is closely aligned with the NEC (National Electrical Code, NFPA 70) and UL standards.
Side-by-Side Comparison
| Feature | IEC 81346 | NFPA 79 |
|---|---|---|
| Issuing Body | IEC (International) | NFPA (USA-based) |
| Geographic Scope | Global (ex-North America) | USA, Canada (with CSA) |
| Reference Designation | Function-based, hierarchical (=A1+B1-M1) | Simpler tag-based (e.g., M1, CB1) |
| Wire Numbering | Defined by the standard’s structure | More flexible; often sequential or page-based |
| Component Identification | Structured prefix system (=, +, –) | Alphanumeric tags with drawing references |
| Control Panel Voltage | Up to 1000V AC / 1500V DC | 600V AC / 1000V DC (for control circuits, 120V preferred) |
| Grounding/Earthing | IEC earthing terminology and symbols | NEC/NFPA grounding rules apply |
| Enclosure Ratings | IP ratings (e.g., IP65) | NEMA ratings (e.g., NEMA 4) |
| Safety Circuit Design | EN ISO 13849 / IEC 62061 references | NFPA 79 has its own safety stop category requirements |
| Schematic Symbols | IEC 60617 symbols | ANSI/IEEE symbols |
| Cable Colors | IEC color coding (brown/blue/green-yellow) | NEC color coding (black/white/green) |
The IEC 81346 Reference Designation System Explained
The most distinctive feature of IEC 81346 is its structured reference designation — a systematic way of identifying every device based on three aspects:
| Prefix | Aspect | Meaning | Example |
|---|---|---|---|
= | Function aspect | What does it do? | =A1 (Control System A, function 1) |
+ | Location aspect | Where is it installed? | +B1 (Building 1, cabinet B) |
– | Product aspect | What is the item? | –M1 (Motor 1) |
A fully qualified IEC 81346 reference looks like:
=A1+B1–M1This means: Motor 1, located in Cabinet B of Building 1, performing function A1.
In practice, most projects use a simplified version, but the hierarchical structure enables:
- Cross-project consistency — the same designation logic applies across all projects in your facility
- Easier lifecycle management — replacement parts and maintenance records link directly to designations
- Multi-discipline integration — mechanical, electrical, and instrumentation teams use the same system
EPLAN Electric P8 is built natively around the IEC 81346 structure, which is why it is the preferred tool for IEC-compliant projects.
NFPA 79 Key Requirements You Must Know
If you are designing for the US market, NFPA 79 imposes specific rules that differ significantly from IEC practice:
1. Control Circuit Voltage
NFPA 79 strongly prefers 120V AC for control circuits (Section 9.1). While other voltages are permitted with conditions, most US-based clients expect 120V control wiring. This is a major difference from European projects where 24V DC control is standard.
2. Conductor Color Codes
| Conductor | NFPA 79 (NEC) Color | IEC Color |
|---|---|---|
| Line (Phase) | Black | Brown |
| Neutral | White | Blue |
| Ground (PE) | Green / Green-Yellow | Green-Yellow |
| 24V DC Positive | Red (common practice) | Red |
| 24V DC Negative | Blue (common practice) | Blue |
Mixing these up on a panel destined for the US is a common — and costly — mistake.
3. Enclosure Ratings: NEMA vs IP
US clients specify NEMA ratings; IEC clients use IP ratings. They are similar but not identical:
| NEMA Rating | Approximate IP Equivalent | Key Difference |
|---|---|---|
| NEMA 1 | IP10 | NEMA 1 has no liquid protection |
| NEMA 4 | IP65 | NEMA 4 adds external ice testing |
| NEMA 4X | IP66 | NEMA 4X adds corrosion resistance |
| NEMA 12 | IP52 | NEMA 12 is dust-tight, drip-proof |
Always confirm with your client which rating they require — do not assume.
4. Safety Stop Categories
NFPA 79 Section 9.2 references stop categories from IEC 60204-1 but applies them with specific US-market expectations. Most US OEMs require Category 0 or Category 1 stops for machine safety — always verify with the machine builder.
How to Choose: Decision Framework
Use this simple decision tree for your next project:
Where will the machine or panel be installed?
│
├─ USA / Canada → NFPA 79 (mandatory for US market)
│
├─ Europe / Middle East / Asia / Australia → IEC 81346 + IEC 60204-1
│
└─ Exported globally (multi-market machine)?
│
├─ Primary market = USA → NFPA 79 base + document IEC deviations
└─ Primary market = non-USA → IEC base + add UL listing if US export neededWhat your client’s purchase order says always wins. If a UAE client specifies IEC and a US client specifies NFPA 79, deliver exactly what is specified — not what is easier for your team.
Can You Design to Both Simultaneously?
Yes — and it is increasingly necessary for globally exported machinery.
At Vidhasri Technology, we handle dual-standard projects by:
- Designing the base schematic to IEC 81346 (EPLAN’s native strength)
- Producing a NFPA 79-translated documentation package — including ANSI symbol sets, NEC color callouts, NEMA enclosure ratings, and 120V control circuit variants
- Maintaining two drawing sets in EPLAN — one IEC-tagged, one NFPA-tagged — linked to the same underlying project data
This is possible because EPLAN’s database-driven design allows you to change the presentation layer without re-drawing the circuit logic.
Common Mistakes We See in Practice
Mistake 1: Using IEC symbols for a NFPA 79 project
ANSI/IEEE symbols (used in US practice) look significantly different from IEC 60617 symbols. A US inspector or end-client will notice immediately.
Mistake 2: Forgetting 120V control circuit requirements for US projects
Designing a 24V DC control circuit for a US machine is technically permissible under NFPA 79 with proper documentation, but it will generate friction with US-based maintenance teams, inspectors, and clients who are accustomed to 120V.
Mistake 3: Applying IP ratings on a NEMA-specified panel
Verify the rating type required. Shipping a panel with an IP65 stamp to a client who specified NEMA 4X (corrosion-resistant) may cause rejection even though the IP protection level appears equivalent.
Mistake 4: Partial IEC 81346 designation
Some teams use IEC 81346 reference designations inconsistently — applying the = function prefix on some devices and not others. This makes automated BOM generation unreliable and creates confusion during maintenance.
How Vidhasri Technology Applies Both Standards
We deliver projects compliant with:
- IEC 81346 reference designation and documentation structure
- IEC 60204-1 machine electrical equipment safety requirements
- NFPA 79 for US/North American market machinery
- NEC (NFPA 70) for US installation-side requirements
Our EPLAN-based workflow ensures that once the project data is correctly structured, producing a standards-compliant documentation package — whether IEC or NFPA — is a report generation task, not a re-engineering task.
Contact us for a standards compliance review of your project.
Summary: IEC 81346 vs NFPA 79 at a Glance
| Question | IEC 81346 Answer | NFPA 79 Answer |
|---|---|---|
| Who publishes it? | IEC (Geneva) | NFPA (USA) |
| Where does it apply? | Global (especially EU, ME, Asia) | USA, Canada |
| How are devices labelled? | Hierarchical function/location/product | Simpler alphanumeric tags |
| What voltage is preferred for control? | 24V DC (common), 230V AC | 120V AC (strongly preferred) |
| What symbols are used? | IEC 60617 | ANSI/IEEE |
| What enclosure rating is used? | IP (IEC 60529) | NEMA |
| Best tool to design? | EPLAN Electric P8 | EPLAN, AutoCAD Electrical |
Final Word
Neither standard is “better” — they serve different markets with different regulatory environments. The right standard is the one your client and installation country require.
The key is to know both, design systematically, and use a tool like EPLAN that supports both frameworks without forcing you to choose a completely different workflow.