---
title: Shelly 400A CT Pro 3EM Split Core Current Transformer For Shelly Pro 3EM
date: 2025-10-13T05:35:32Z
modified: 2026-05-12T10:02:35Z
permalink: "https://tech.co.za/product/shelly-400a-ct-pro-3em-split-core-current-transformer-for-shelly-pro-3em/"
type: product
status: publish
excerpt: The Shelly 400A Current transformers scale the largevalues of current to small, standardized values for measuring purposes. Theyprovide a secondary current that is accurately proportional to the currentflowing in its primary circuit. The current transformer presents a negligibleload to the primary circuit *Only compatible with Shelly Pro 3EM-400A. Features Snap-on, screwless mounting system
wpid: 554671
product_brand:
  - Shelly
product_type:
  - simple
product_visibility:
  - featured
product_cat:
  - Smart Home
featured_image: "https://tech.co.za/wp-content/uploads/2025/10/SHELLY-400A-CT-PRO-3EMa.png"
---

The Shelly 400A Current transformers scale the largevalues of current to small, standardized values for measuring purposes. Theyprovide a secondary current that is accurately proportional to the currentflowing in its primary circuit. The current transformer presents a negligibleload to the primary circuit \*Only compatible with Shelly Pro 3EM-400A. Features Snap-on, screwless mounting system

### Diagrams

**INSTALLATION**

![](https://shellysa.co.za/wp-content/uploads/2025/06/CT-cable.png)

**LEGEND**



| **A** | Shelly CT400A |
| --- | --- |
| **B** | Cable tie (another one on the opposite side) |
| **C** | Primary conductor |

### SPECIFICATIONS



| Type | Value |
| --- | --- |
| **Physical** |  |
| Size (HxWxD): | 84x54x48 ±0.5 mm / 3.31×2.13×1.89 ±0.02 in (without the cable) |
| Weight: | 290 ±1 g / 10.23 ±0.05 oz (with the cable) |
| Conductor aperture: | Ø35 mm / 1.38 in |
| Core: | Ferite |
| Shell material: | Plastic |
| Color: | White |
| **Environmental** |  |
| Ambient temperature: | -10 °C to 50 °C / 14 °F to 122 °F |
| Humidity: | 0 % to 80 % RH |
| Max. altitude: | 2000 m / 6562 ft |
| **Electrical** |  |
| Primary/secondary current ration: | 3000/1 |
| Rated max. primary current: | 400 A |
| Electrical strength: | 3000 VAC, 60 sec |