Should You Install Low Voltage Cables Overhead or Under the Floor?

Under the floor low voltage cabling reduces unsightly cables, but can have a higher total cost of ownership than overhead cabling.  If you have the option of overhead or under the floor cabling for your low voltage cable, overhead cabling can offer as much as 24% energy savings over under-floor cabling give you more aesthetic leeway over flooring choices.

Energy Waste from Under Flooring

There are three ways under-flooring cabling contributes to energy loss :

  • Cables block airflow
    Old unused cables are often left in place when new network or power cables are added under the floor.  These unused cables block air passage and enable hotspots. These cause energy waste.

  • Rack cable cutouts allow bypass of cooled air
    Most cable cutouts are not entirely filled with cabling. The unfilled areas in these cutouts let cooled air escape.  This means that a cooling system will have to use more power to achieve the same cooled temperature.

  • Power distribution units (PDUs) allow bypass of cooled air
    PDUs require a 9-16 square foot opening for installation and removal of conductors. These openings allow air to escape, just as in the rack cable cutouts mentioned above.

Energy Savings from Overhead Cabling

Overhead cabling allows for lower fan losses and lower pump losses.  Victor Avelar of Schneider Electric modeled a hypothetical data center that showed the savings from moving cables to overhead cable trays (see white paper here for details).  Avelar’s model showed that moving cabling overhead lead to a 13% reduction in leakage, reduction of CRAH units from 42 to 31 and an estimated savings of 24% in fan and pump power.

Greater Flexibility in Flooring Materials

Moving away from under the floor cabling allows greater flexibility in flooring options.  Under the floor cabling requires specific structural requirements for flooring setup. Overhead cabling allows buildings more freedom in choosing and designing their flooring. In Savannah, hardwood flooring is often a preferred material for high end real estate like law offices and some university buildings.  Choosing overhead cabling can give a lot more leeway for aesthetic choices in flooring.


Overhead cabling can save money in many low voltage wiring scenarios.  It also enables companies more leeway in making aesthetic choices for their flooring.  While there are still situations where under the floor cabling may be the best option, overhead cabling may frequently offer the largest cost savings.