9.2 Float Switch (Full Tank Shut-off)
We recommend the use of a float switch or other means
to prevent overflow of your tank. This will stop the pump
when the tank is full, then reset when the level drops. This
conserves ground water, prevents overflow, and eliminates
unnecessary pump wear. PS2 controllers allow the use of a
small signal cable to a remote float switch, even if the tank
is a long distance away.
Float switch requirements:
(1) A switch must be used, not wet electrodes.
(2) The preferred system requires a float switch to OPEN
contact on rise to turn the pump OFF. This is called
“normally closed” (N.C.).
Float switch cable requirements:
(3) Two wires are needed.
(4) Minimum wire size 1 mm² / AWG 18. This is good for a
distance as far as 600 m / 2,000 ft.
(5) The cable must be suitable for its environment.
(6) If it must run a long distance, use twisted-pair shielded
cable to reduce the chance of damage from light-
ning-induced surge.
Grounding shielded float switch cable – If you use
shielded cable, connect the shield to ground at the control-
ler only. Do not ground the shield at the float switch. This
will reduce surges induced by nearby lightning.
Operation of the float switch system – When the
water level is high, the float switch will stop the pump. The
remote switch indicator on the controller will light up. When
the water level drops, the float switch will signal this to the
controller. The indicator light will turn off, and the pump will
restart if sufficient power is available.
Wiring to the controller – The float switch must be
wired to the controller at terminal 3 and 4, cf. “7.6.3 Pump
Accessories Wiring” on page 27.
Manual remote control switch – The float switch circuit
can be used with a manual switch to turn the pump on and
off from a distance. Use any simple on/off switch available
from an electronic supply, electrical supply, or hardware
store (it only carries low voltage, very low current). Wire it
according to the illustration above, for a normally closed
float switch.
Figure 22: Float switch scheme
sealed
cable clamp
position pump off
pumping
range
position pump on
cable
weight
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