Large facilities, such as schools and universities, manufacturing plants, hospitals and corporate locations, generally have three options when it comes to timekeeping:

(1) Serial Digital Clock Systems
(2) Wireless Digital Clock Systems
(3) Power over Ethernet (PoE) digital clocks.

The time savings a synchronized clock system provides are exponential, but there are many considerations for deploying a facility-wide digital clock system, whether it be serial, wireless or PoE. This page will explore the key monetary and non-monetary considerations and compare the total cost of ownership (TCO) for each digital clock system.

Serial Digital Clock Systems
Serial digital clock systems have been around for many years. These clocks require a 240V outlet and a serial plug for power. Another power option is an extra pair of wires for 24V DC power in case of a power outage. The wiring these digital clocks require makes serial clock systems an expensive solution, compared to PoE digital clocks.

Key monetary cost considerations for a serial digital clock include the purchase price, the cost of syncing the time to the network, installation of a 240V outlet and serial plug to power the clock, and, if power backup is required, additional wiring costs to provide backup power in the event of a power outage.

Monetary Cost Considerations (per digital clock) Average Price (in US$)
Purchase price $200-$400
Time sync $275
Power $150 (installation of 110V outlet and serial plug)
Power backup Additional wiring in case of power outage, optional
Total monetary cost $850 + optional power backup

Wireless Digital Clock Systems
Wireless digital clocks are essentially the second generation of clock systems. These clocks receive time from a transmitter that must be located in the building. The transmitter sends a low-wattage signal with the time to each digital clock. Wireless digital clocks require the installation of expensive AC outlets.

Key monetary cost considerations for a wireless digital clock include the purchase price, the antenna system which syncs the time to the network, and installation of an AC power drop to power the clock.

Monetary Cost Considerations (per digital clock) Average Price (in US$)
Purchase price $350
Time sync: antenna system $500-$625
Power $125 (installation of AC power drop)
Power backup $0
Total monetary cost $1,100

Power over Ethernet Digital Clock Systems
PoE is an exciting and relatively new technology that simplifies implementation and maintenance of a clock system. There is no need for AC outlets, battery replacements, daylight saving time adjustments, or additional software. A PoE Clock gets is time and power from the network cable. A network administrator can easily control one or hundreds of clocks from any PC on the network with a simple session. The option of centralized uninterruptible power supply (UPS) backup allows PoE devices to continue running even in the event of a power failure.

Key monetary cost considerations for a PoE digital clock systems include
- The purchase price. 
- The likelyhood that an Ethernet jack will already exist in the required location.
- Installation of an Ethernet port. It's worth noting, that Ethernet port installation can usually be done by IT staff to save on installation costs. 

Two of the unique cost benefits to PoE clocks are energy efficiency and no additional required costs for time syncing or power backup.

Monetary Cost Considerations (per digital clock) Average Price (in US$)
Purchase price $395-$445
Time sync $0
Power $100 (installation of Ethernet jack) and $27.50 (PoE injector if needed)

Power backup $0 (with network power backup)
Total monetary cost $395-$575

Non-monetary Cost Considerations
No matter which digital clock system you're considering, there are several factors that can affect the success of your implementation even though they don't directly impact the final cost. These include:

• Failure rate: Downtime can be costly, especially when clocks are mission-critial. Digital clocks have an extremely low failure rate.
• Accuracy: Accurate time is essential, especially in hospitals and other facilities where time is mission-critial. PoE clocks are accurate within approximately +/- 200 milliseconds.
• Viewing disance and angle: The viewing distance and angle will directly impact the number of clocks you'll need to purchase to keep everyone in the facility aware of the time. PoE digital clocks can be seen from a distance of 40+ metres and a 140° angle.
• Automatic time updates: PoE clocks automatically update for daylight saving time, providing valuable time savings twice every year. Not all clock systems automatically update, so consider the time spent manually updating each clock.

The time and cost savings that PoE clocks provide make a huge impact on clock deployments of any size. Just one PoE digital clock is about half the cost of one serial digital clock and half the cost of one wireless digital clock.

Energy-efficient, PoE technology is clearly the answer.