Electronic Twist-Lock Photocontrols:
Power Consumption

The big deal about photocontrol power requirements - Cost of Operation

The seemingly low level of power required for operating individual photocontrols becomes exceedingly significant when considering the large quantities generally required.  Multiply the number of photocontrols by the power required for each, and the overall power requirements become obvious.

How Much? $$$

The cost of operating electrical loads is broken into two parts:

Energy Consumpion - measured in Kilowatt-hours (KWH)
Electrical Demand (Connected Load) - measured in Kilowatts (KW)

Calculating the cost for Energy Consumption is straight forward, and is the sum of power requirements accumulated over time.

Calculating the cost associated with Electrical Demand can be much more complex.  A demand charge is levied monthly based on the maximum average rate of energy consumption over a time period of measurment (typically 15 or 30 minutes).  This time period of measurment is generally referred to as the Demand Interval.  Additionally, many utility rates include provisions for assessing Peak Demand charges based on the single highest Demand Interval occuring during summer months, that can substantially affect utility bills for the month of occurrence, and each of the following eleven months.

A review of local utility rates will reveal the impact for each individual case.

Photocontrols are not created equal

In a recent study Ripley engineers tested the power requirements of individual off-the-shelf 120 volt photocontrols manufactured by Ripley and three competitors.3

Testing results were as follows:

Potential $$$ savings using Ripley = 72%

As depicted in the chart at right, measured performance of Ripley's 120 volt photocontrol over that of competitor "C" represents a 72% reduction in power requirements.  By applying this reduction to both energy consumption charges and electrical demand charges, annual cost savings for the above example can be calculated as follows:

Annual Energy Cost Savings for above example:

$141,912 Consumption + $21,600 Demand X 72% reduction in power requirements = Savings of $117,729 per year

1. National Commercial Average from the Energy Information Administration, October 13, 2005.
2. Center for Energy Efficiency and Renewable Energy, university of Massachusetts Amherst
3. Actual Testing Included:
   Ripley (SouthConn Technologies Inc.) Model 6246B measured 0.5 watts
   Sunrise Technologies / Fisher Pierce Model S120-1.5 STM measured 1.4 watts
   Area Lighting Research (ALR) Model 2060NC1 measured 1.8 watts
   Precision Lumitrol Model P2-455L measured 1.6 watts
   Measurements taken with photocontrol in off state (street light off) at 120 vac