Plastic cabling trays interfere with signals?
July 9, 2010We 
recently heard of an odd comment from a vendor. As the source heard it, a prospective vendor recommended against plastic cabling trays “as they interfere with the signals.”
That is clear case of vendor FUD. Or is it?
On one hand Plastic, especially PVC, absolutely can and does conduct RF over short distances. To solve this, placing RF shunts in-line for short cables, in the form of a ferrite core toroid or square with the cable reverse wrapped in two coils around the core to cancel the RFI.
On the other hand, I can’t for the life of me think of a large enough source of interference which would travel along a plastic tray to cause RFI. Any such source would induce a signal around the cables’ plastic shells themselves before you’d have to worry about the tray the cables are in.
Verdict?
Vendor FUD. The customer should chase the vendor from the building and not validate his parking.
However enterprises place high-value on robust, scalable, network infrastructure for servicing voice, data, and video traffic. Before implementing any change to your enterprise network, carefully define the requirements and deployment methods. For example:
- Metal or wire cable trays must be grounded and bonded properly as improperly grounded/bonded cable trays can in some situations induce electron magnetic interfere (EMI).
- Further, to minimize induced interference, don’t allow Category 5 (or other Cat cables) cables to cross power cables at right angles.
- Likewise, don’t run telecommunications cabling in the same conduit or through the same metal stud opening as power wiring.
- Be aware of the fire codes associated with the environment you are installing plastic cable trays in. For example, plastic cable trays could be banned in many industrial settings as a fire hazard.
- For any enterprise network deployment, use our Structured Cabling RFP to ensure the deployed cable infrastructure provides the best options for maximizing utilization, scalability, and reliability of the network infrastructure.
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