TL;DR
NEMA VE 1-2017 load classes are a two-part code: a number (support span in feet) and a letter (working load per metre). Here is every combination at a glance:
| Class | Span | Load per metre | Total load over span |
|---|---|---|---|
| 8A | 2.4 m (8 ft) | 74.4 kg/m | ~179 kg |
| 8B | 2.4 m (8 ft) | 111.6 kg/m | ~268 kg |
| 8C | 2.4 m (8 ft) | 148.8 kg/m | ~357 kg |
| 12A | 3.6 m (12 ft) | 74.4 kg/m | ~268 kg |
| 12B | 3.6 m (12 ft) | 111.6 kg/m | ~402 kg |
| 12C | 3.6 m (12 ft) | 148.8 kg/m | ~536 kg |
| 16A | 4.8 m (16 ft) | 74.4 kg/m | ~357 kg |
| 16B | 4.8 m (16 ft) | 111.6 kg/m | ~536 kg |
| 16C | 4.8 m (16 ft) | 148.8 kg/m | ~714 kg |
| 20A | 6.0 m (20 ft) | 74.4 kg/m | ~447 kg |
| 20B | 6.0 m (20 ft) | 111.6 kg/m | ~670 kg |
| 20C | 6.0 m (20 ft) | 148.8 kg/m | ~893 kg |
Metosu’s cable ladder is independently tested to 1,340 kg at a 2.4 m span — that is 2.5× the Class 8C minimum. Our cable tray is tested to 420 kg at the same span, exceeding the Class 8B minimum. Both verified by Sucofindo.
The naming system
The standard is NEMA VE 1-2017, published jointly with CSA C22.2 No. 126.1-17. It defines how metal cable tray and cable ladder systems are classified and tested in North America — and it is the framework most consulting engineers in Southeast Asia reference when they write a load class on a drawing.
Every class is built from two parts:
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First digit — the support span, in feet. 8 ft = 2.4 m, 12 ft = 3.6 m, 16 ft = 4.8 m, 20 ft = 6.0 m. This is the distance between the two supports that hold the tray or ladder. Most indoor installations use the 8 ft (2.4 m) span as the baseline.
-
Letter — the working load per linear metre. A = 74.4 kg/m (light), B = 111.6 kg/m (medium), C = 148.8 kg/m (heavy). This is the uniformly distributed cable weight the system must carry without exceeding the deflection limit.
Put them together and the class tells you everything in two characters. Class 8C = 2.4 m span, 148.8 kg per metre, roughly 357 kg total. Class 12A = 3.6 m span, 74.4 kg per metre, roughly 268 kg total.
NEMA VE 1 sets the working-load deflection limit at L/100 — for a 2,400 mm span, that is 24 mm. Metosu’s cable ladder and tray are independently verified by Sucofindo against a far stricter L/250 limit — 9.6 mm at a 2,400 mm span, a deflection ceiling 2.5× tighter than NEMA VE 1 itself requires.
One detail engineers miss
For wider spans, the maximum working load per metre decreases relative to the total structural capacity of the section. A Class 20C system carries 148.8 kg/m over 6.0 m, but the bending moment on the side rail is much higher than on a Class 8C system at the same per-metre load. When you increase the span in a specification, check that the product’s tested capacity still covers your total load — not just the per-metre figure.
How Metosu’s products map to the classes
Both products below were tested by Sucofindo (via IDSurvey) against the NEMA VE 1-2017 test method, at a 2,400 mm support span, on 14 July 2025.
Cable ladder — NEMA Class 8C
| Parameter | Value |
|---|---|
| Sample | SLU W600×H100×L3000 |
| Steel thickness | 1.95 mm |
| Test span | 2,400 mm |
| Load at failure | 1,340 kg |
| Class 8C minimum | 534.4 kg |
| Margin | 2.5× the requirement |
| Tested deflection | L/250 = 9.6 mm |
| Sucofindo report | E26929/FNBPAS, issued 18 July 2025 |
The 534.4 kg minimum accounts for the NEMA VE 1 safety factor applied to the Class 8C working load over the tested span. Metosu’s ladder held 1,340 kg before sample damage — comfortably above the threshold.
Cable tray — NEMA Class 8B
| Parameter | Value |
|---|---|
| Sample | TRU W300×H100×L3000 |
| Steel thickness | 2.02 mm |
| Test span | 2,400 mm |
| Load at failure | 420 kg |
| Class 8B minimum | 403 kg |
| Margin | Exceeds requirement |
| Tested deflection | L/250 = 9.6 mm |
| Sucofindo report | E26933/FNBPAS, issued 18 July 2025 |
The tray meets the Class 8B threshold at the standard 2.4 m span. For heavier runs — anything above ~50 kg per linear metre — ladder is the correct specification.
What to write on your drawings
If you are the specifying engineer, here is what to write and what it means:
-
“NEMA VE 1, Class 8C” — you are asking for a cable ladder or tray that can carry 148.8 kg per metre at a 2.4 m support span, within the NEMA VE 1 deflection limit. This is the most common class for industrial and data-centre power distribution in Indonesia.
-
“NEMA VE 1, Class 8B” — the medium-load class at the same span: 111.6 kg per metre. Typical for commercial LV power and mixed power-data runs.
-
“NEMA VE 1, Class 8A” — the light-load class: 74.4 kg per metre. Suitable for data-only and light control cabling.
If your project requires longer spans (12 ft / 3.6 m or more), specify the corresponding class — but confirm with the manufacturer that the product has been tested at that span. Metosu publishes full span/load tables per SKU in PART II of our catalogue.
A note on IEC 61537
Some projects reference IEC 61537:2023 instead of NEMA VE 1. IEC 61537 uses a different classification method — it specifies safe working load (SWL) directly in Newtons rather than a letter-based class system. Both standards test uniformly distributed loads at defined spans with deflection limits, so the engineering principles are the same. Metosu’s Sucofindo test reports are structured to satisfy both frameworks.
When class alone is not enough
The NEMA class tells you the static uniformly distributed load rating. It does not cover:
- Point loads — a technician standing on a ladder rung, or a heavy junction box mounted mid-span. If your run sees concentrated loads, ask the manufacturer for a point-load test or calculation.
- Dynamic loads — seismic zones, vibrating machinery, offshore installations. These require additional engineering beyond the VE 1 static-load framework.
- Corrosion performance — the class says nothing about finish or substrate. Metosu ships hot-dip galvanised (75–100 µm zinc) or Jotun powder-coat (60–80 µm) across all product lines. Specify the finish separately.
Contact engineering
For project-specific load calculations, span tables, or Sucofindo report copies, email marketing@metosu.com. We review cable-management specifications as a pre-sales service — send a cable schedule and support layout and we will confirm the class, product line, and finish within one business day.
Further reading
- NEMA VE 1-2017 — the North American metal cable tray standard and source of the load class framework.
- CSA C22.2 No. 126.1-17 — the Canadian companion standard, published jointly with NEMA VE 1.
- IEC 61537:2023 — the international standard for cable tray and ladder systems.
- Metosu cable ladder · Metosu cable tray
- Catalogue download (EN) · (ID)
