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WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS
WATER CONTAMINANT LEVELS
WATER HAMMER NOISE DIAGNOSE & CURE
WATER ODORS, CAUSE CURE
WATER PUMP REPAIR GUIDE
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PUMP SHORT CYCLING
WATER SOFTENERS & CONDITIONERS
WATER TANK REPAIR PROCEDURES
WATER TANK: USES, TROUBLESHOOTING
WATER TESTS, CONTAMINANTS, TREATMENT
WATER TREATMENT EQUIPMENT CHOICES
WELLS CISTERNS & SPRINGS
WELL FLOW RATE
WELL WATER PRESSURE DIAGNOSIS
WELL YIELD IMPROVEMENT
WINTERIZE A BUILDING
This article describes how to find, use, diagnose, install and wire-up or repair the a water pump relay switch (well pump relay). The page top photo shows a typical wall-mounted Goulds ™ relay switch used to power a submersible well pump. The well pump relay switch is used to turn on and off higher horsepower well pumps. The pump pressure control switch operates the pump relay switch that in turn operates the pump.
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Where will I find the pressure control switch and where is the pump relay switch?
The water pump pressure control switch (orange arrow in photo at below left) and the pump relay switch (below right) are two different devices. As we explain below, all well pump systems require a pressure control switch to sense the water pressure and turn the pump on and off as needed. But when a higher horsepower submersible pump is used, a separate pump relay (red arrow in photo below right) is used to actually control turning the pump on and off.
Well Pump electrical power switch: In the photo at above right, you'll note a third control marked by the white arrow. This is the main electrical power shutoff for the well pump. Some pump relay covers, when removed, include a pull-out switch that cuts electrical power to the pump. This is a handy detail to know: if your well pump relay switch is of that type, and if the cover of the switch is not securely installed, your well pump could lose electrical power and the building will have no water.
Watch out: while the pressure control switch is usually easy to find (located on or close to the water pressure tank) the pump relay switch might be found nearby, say on a wall (photo below left) or it might be hidden away in a closet or crawl space (photo above right).
When do we use a pump relay switch
A pump relay switch such as the relay switches shown in photographs in this article is used to power a water pump when the voltage/amperage combination would be too much to switch on and off by the simple pump pressure switch.
Larger horsepower submersible well pumps draw more than 15A, sufficient amperage that if they were wired through a little pressure control switch at the water tank that switch would burn up pretty quickly.
The specifications and load handling capacity of the pump relay switch are found on the switch cover or body, or sometimes on a sticker located inside the switch cover. A closer examination of this data (above right, click to enlarge) indicates the horsepower rating of the pump that the switch is intended to handle - in the case of our photo, it's a 1/2 hp submersible well pump wired for up to 230V (and at 5this voltage drawing just 7.7Amps).
Technical note: if the well pump offers the option of wiring at either 120V or 240V, we prefer to wire for 240V service. If you need help sorting out the definitions of current (amperage or amps), voltage, and watts, see DEFINE AMPS VOLTS WATTS.
When are pump relay switches not used?
Many well pump installations use only the pressure control switch to operate the system, so separate pump relay switches are not installed on every water pump. Separate pump relay switches are usually not found when the water pump is above ground such as when a one line or two line jet pump is installed at or near the water pressure tank and they are generally not used on smaller horsepower submersible well pumps that draw 15A or less of current. For those installations, a WATER PUMP PRESSURE CONTROL SWITCH is sufficient.
Where is the "electrical ON-OFF switch" when a wall mounted heavy duty pump relay is installed?
We may not see a separate wall mounted electrical switch by the pump controls when a heavy duty relay such as those discussed here is installed. Rather, on at least some of these switches, pulling off the cover of the relay box will actually disconnect internal components and thus serves as a local electrical switch for the water pump.
Safety warning live voltage is inside of all of these pump switches - and is a shock hazard. When you don't see an ordinary wall switch to turn off the water pump you're probably safer going to the electrical panel where you can turn off power to the water pump by switching off the appropriate circuit breaker or pulling the appropriate fuse.
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