Automatic Control For Full-Tank Shutoff4.10
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. PS controllers allow the use of
small signal cable to a remote float switch, even if the tank
is a long distance away.
Float switch requirements
A switch must be used, not wet electrodes.1.
The preferred system requires a float switch to MAKE 2.
contact on rise to turn the pump OFF. This is called
“normally open” (N.O.). It may be commercially
labeled as a “pump down” switch, but here it works
in reverse, to allow pumping up.
Float switch cable requirements
Two wires are needed.1.
Minimum wire size #18 AWG (1 mm2.
2
). This is good
for a distance as far as 2,000 ft (600 m).
The cable must be suitable for its environment.3.
If it must run a long distance, use twisted-pair 4.
shielded cable to reduce the chance of damage from
lightning-induced surge. See section 5.2, Grounding
and Lightning Protection
Grounding shielded float switch cable If you use
shielded cable, connect the shield to ground AT THE
CONTROLLER ONLY. DO NOT ground the shield at the float
switch. This will reduce surges induced by nearby lightning.
Wiring to the controller (junction box) The controller
(and junction box) offers two options for connection of a
remote switch. These allow the use of either a “normally
open” (N.O.) or a “normally closed” (N.C.) switch. “Nor-
mal” refers to the status of the contacts when the switch is
DOWN and calling for water.
QUESTION Why do we use a
reverse-action (N.O.) oat
switch? (a pump-down switch
for a pump-up application) — ANSWER If the
cable connection is broken, the pump will
continue to operate. The water supply will not
be disrupted (but of course, the tank will
overow). This is the general preference in the
industry. If you prefer the pump to stop if the
connection is broken, use a normally closed
(N.C.) oat switch instead.
Float switch schemeFigure 10:
Wiring a “normally closed/reverse action float switch”Figure 12:
Connect the switch to termins 4 and 5. Closing (connecting) the switch turns the pump ON
Wiring a “normally open float switch” Figure 11:
Connect the switch to terminals 3 and 4 (NO and common) and connect terminals 4 and 5 together, as illustrated.
Closing (connecting) the switch circuit turns the pump OFF
sealed cable clamp
position pump off
pumping range
float switch
UP: closed
DOWN: open
normal: open
UP: open
DOWN: closed
normal: closed
if cable is shielded,
ground this end only
if cable is shielded,
ground this end only
position pump on
cable weight
float switch
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