Answered: Toroid Use on 4-Wire Cables

Is it legal to take a toroid from a broken motor and put it on the communication wires for the integrated motor encoders? My team is doing this to try and reduce error from the integrated quad encoders, and so far we have yet to drop a connection between the cortex and encoder.
We do not cut any of the wires, but we remove the pins from the connector to get the toroid on, then we replace the pins and zip tie the wires together so they do not snag on anything. I attached a photo of what the “mod” looks like, and I want to know if this is legal so we can remove it from our robots by worlds.

This is not legal.

Could I ask which rule this violates and why?

Yes you may! I’ve quoted <R15a> below.