Do I need shielding on gigabit ethernet cables?

– Copied from a customer email –

Instead of using the daughter board, we prefer to integrate the BotBlox switch on the PCB with BotBlox custom Picoblade to Picoblade 8 way cables.

Is there a risk with the absence of shielding? And if so, do you think there is a possibility to have a similar cable with shielding as well?

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Shielding is always a controversial subject in electronics so it’s difficult to give a short answer on this, but I’ll do my best.

Shielding on a cable provides two benefits:

  1. Preventing external EMI from making its way your signal of interest in the cable.
  2. Preventing EMI from signals from escaping out of the cable.

Thus, whether you need shielding highly depends on your application. Certainly 1000BASE-T does not need shielding to work, and in fact standard CAT5 network cables are unshielded. The situation changes if you’re operating in a high noise environment, or over a long distance. In those cases, adding shielding can make a difference.

Let’s say, for example, you are wiring up a drone and you have an ethernet signal passing very close to a motor driver. That motor driver is going to be serious source of EMI, and one could expect it to cause noise in the ethernet signal, thus causing connection issues. You really don’t want a situation where your drone suddenly loses connectivity the moment your motors spin up :wink: . In this situtation, shielding would probably help. However, it’s probably better for you to just route your ethernet cable away from any noise sources but doing a bit of design work on the cable routing in your system. Doing so would probably avoid the need for that extra shielding (which adds extra weight to your drone).

Another example might be a 300 meter cable run between machines on a factory floor. In this case, that 300 meter cable sure has a lot of opportunities to pick up EMI from the environment, even if there aren’t huge EMI sources nearby. In this case, you’re probably going to want shielding and there’s probably not anyway round that. That being said, you’re probably also going to be fine without shielding, but you take the risk of issues later.

All BotBlox boards by default, do not include a shielding pin on the connector. This was a decision we took early on in the design stage. BotBlox boards are generally used inside mobile platforms where size and weight are limited. They’re also used in devices where the engineer has a lot of control over cable routing. With this in mind, we made the decision that adding shielding to all of our boards does not add significant benefit to our customers. Also bear in mind the fact that we sell bare boards (at least for now), and so if a customer embeds our board into their chassis, they can just use chassis ground for their shield.

I’m certainly not saying that our approach is the only correct approach, but given that our focus is on compactness, it was the right approach for us.

That brings us to your application… Only you can really answer if you need shielding or not. Take into consideration whether your ethernet signal will be subject to large EMI sources? Will it be a long cable run? Feel free to share a little more on your overall system and I can advise. If it’s sensitive, you can always email me at

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