Wiring Sizing For 24VAC Solenoids and the Swell Solution
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24VAC
solenoids generally require a minimum of 20 VAC for reliable operation.
The corresponding allowable voltage drop is therefore 24- 20 = 4VAC.
The wire sizing chart is based on a 4 volt drop allowance. With a
SWELL used on the valve, a 6 volt drop is permitted.
Solenoid inrush current is used to calculate wire size. When multiple valves are energized simultaneously on the same line, add the solenoid inrush currents. If inrush is given in volt-amps (VA), divide by 24. DO NOT USE THE WATT RATING. VA is not the same as watts for AC solenoids. Inrush current is listed along the top of the chart. Up to 5 SWELLS are also listed across the top with their inrush currents pre-calculated.
The chart vertical axis shows the distance from the controller to the valve and back in thousands of feet.
Even though wire sizes on the chart are listed from 18 to 2 gauge, the smallest direct burial size recommended is 14 UF solid copper. Sizes larger than 2 are omitted and normally not used because of cost.
For a single valve or multiple valves at the same distance from the controller, use the chart as follows:
Add the total inrush currents of all the solenoids and locate the closest value to this figure along the top of the chart. If SWELLS are used, up to five are listed along the top.
Select the closest round trip distance along the vertical axis.
The box at the intersection indicates the recommended gauge.
Compare wire and energy savings if SWELLS are used.
EXAMPLE 1:
What gauge wire is needed to operate two solenoids, each with an inrush current of 1 .0 amps, located 2000 feet away from the controller? What if SWELLS (one per valve) are used?
Two solenoids
add up to 2.0 amps inrush.
The distance
loop is 2000 feet X 2 = 4000 feet.
Chart shows
that 6 gauge wire is required, shown as circleA on chart.
With two SWELLS
(one per valve), the chart shows that 18 gauge could be used at point circleB. For direct burial, it is
however recommended that 14 gauge be use.
For multiple valves on a line at various distances from controller:
Add the inrush currents as before.
Add distances from controller to each valve and divide by number of valves to get average distance. Multiply aver-age by 2 to get loop distance.
Use chart as before to determine gauge.
Compare wire and energy savings with SWELLS.
EXAMPLE 2:
There are 4 valves along one line. The first is 2000 feet from controller; second is 3000 feet away from controller; third is 3300 beet away; and the last 3700 feet away. Each valve solenoid has an inrush of .5 amps. What size wire should be specified conventionally or with the SWELLS?
Total inrush current is .5 + .5 + .5 + .5 = 2.0 amps.
SWELL BENEFITS:
In example 1 above, the estimated wire cost savings after subtracting for the SWELL cost is about 50%. In example 2, the saving is about 70%. Additional benefits in using the SWELL are as follows:
Holding current draw is reduced by about 80% in example 1 and over 90% in example
This saves energy.
Allows operation of a valve at significantly lower AC voltages and much greater distances.
Extends solenoid life because solenoid coil cannot overheat.
Cuts installation cost because 14 gauge is easier to handle than heavier wires.
Reduces dealer inventory of wire to one size (14 gauge) for most applications.
Intersection Of Inrush Current And Distance Shows
Calculated Solid Annealed Copper Wire Gauge :
Example 1 from the reverse side is shown as circle A and circle B
Example 2 from the reverse side is shown as circle C and circle D
*Wire Size Larger Than 2 Gauge
**Typical Inrush Current of Lawn and Garden Type Solenoid
***Typical Inrush Current of an ASCO "6 Watt" Solenoid
