Question

Question: Hi. I haven't wired any controls or motors in a while so I'm researching and reading to see what I will need to wire a pond pump motor.Back story: New home owners of a house have a pond that was used to supply water to lawn sprinklers. The pump and wiring are in disrepair.They had someone replace the pump. The new pump is single phase, 2 HP, Thermally protected, 230V, FLA 8.3, SF1.4, SFA12.The idea, is to have the existing pool timer zone controller (Hunter) which was controlling an old starter relay, instead control a new starter with heaters that I will put in (researching)Would controlling the 250v starter from the 120v sprinkler control circuit be in violation? ( I will research )FLOW switch?? ... This pump has a 2" pvc pipe going into the pond to supply the water to the pump and sprinklers. If this pipe gets clogged, there is nothing to turn the motor off from what I can see. Would anyone know of a FLOW SWITCH that I can install in that pipe that would break or make the control circuit if that pipe clogs or the pond drys up??Thank you.

Answer 1

Okay, let's break down your pond pump wiring and control project, addressing the safety, code compliance, and functionality concerns.

Understanding the Situation Existing Setup

An old pond pump was used for irrigation, controlled by a pool timer (likely a Hunter sprinkler system).

New Pump

You have a new 2 HP, 230V single-phase pump with specific ratings (FLA 8.3, SF1.4, SFA 12). It's thermally protected, which is good.

Goal

Use the existing Hunter timer to control a new motor starter with overload protection (heaters) for the pump.

Concern

Protection against a dry pump situation (clogged intake or low pond level).

Addressing Your Questions and Concerns1. Sprinkler Controller to Motor Starter (Voltage Compatibility) Potential Violation

Yes, directly controlling a 230V motor starter coil with a 24VAC (most common sprinkler controller output) sprinkler system is definitely a problem. Sprinkler controllers typically use low-voltage AC (usually 24VAC).

Solution

You'll need an appropriately rated relay or interposing relay. The sprinkler controller output would trigger a 24VAC coil relay. The contacts of that relay would then switch the 230VAC power to the motor starter coil.

Important Considerations

Relay Coil Voltage

Make sure the relay coil voltage matches the sprinkler controller's output (most likely 24VAC).

Relay Contact Rating

The relay contacts need to be rated for the voltage and current required by the motor starter coil (usually printed on the starter). Choose a relay rated higher than the coil rating.

Enclosure

Put the relay and any associated wiring inside a suitable electrical enclosure (NEMA 3R or similar for outdoor use).

Wiring

Follow proper wiring practices, including using appropriately sized conductors and wire connectors.2.

Motor Starter and Overload Protection (Heaters) Essential

A motor starter with properly sized overload heaters is absolutely required. This protects the motor from damage due to overcurrent caused by overload conditions (e.g., a partially clogged impeller, pump working too hard). The thermal protection built into the motor itself is a secondary layer of protection.

Sizing Overload Heaters

Use the Motor's FLA

Use the motor's Full Load Amps (FLA) of 8.3A.

Choose Heaters Based on the FLA

Motor starter manufacturers provide charts that list heater element sizes for specific FLA ranges. Select heaters that fall within the range that includes 8.3A. The overload heaters are designed to trip the starter if the motor draws more than its rated current for an extended period.

Consider Service Factor

The Service Factor (SF) of 1.4 means the motor can handle brief overloads up to 1.4 times its FLA without damage. However, you still size the overload heaters based on the FLA, not the SFA (Service Factor Amps). The SFA (12A) is the maximum current the motor can draw at service factor conditions.3.

Flow Switch for Pump Protection Excellent Idea

Installing a flow switch is a very good way to protect the pump from running dry or cavitating due to a clogged intake.

Types of Flow Switches

Paddle Type

These are relatively simple. A paddle is inserted into the pipe, and when flow occurs, the paddle is deflected, activating a switch. These can be prone to clogging and require periodic cleaning.

Thermal Dispersion Type

These use a heated sensor. When flow occurs, the sensor cools down, activating a switch. These are more reliable in dirty water applications, but they are also more expensive.

Ultrasonic Flow Switch

These send a signal through the pipe wall and sense the returning echo. Requires clean pipe walls and little to no debris.

Installation Considerations

Location

Install the flow switch as close to the pump intake as possible, but downstream of the intake strainer/screen (if any).

Pipe Size

Be sure to get a flow switch that is compatible with your 2" PVC pipe. Some switches have different fittings or adapters available.

Switch Type (Normally Open/Normally Closed)

Normally Open (NO)

The switch is open (no continuity) when there is no flow. When flow occurs, the switch closes. Use this if you want to enable the motor starter control circuit when flow is present.

Normally Closed (NC)

The switch is closed (continuity) when there is no flow. When flow occurs, the switch opens. Use this if you want to disable the motor starter control circuit when flow is not present.

Wiring

The flow switch is installed in series with the control circuit of the motor starter coil. This means that if the flow switch opens (due to no flow), it breaks the circuit to the motor starter coil, shutting off the pump.

Suggested Wiring Diagram with Flow Switch

Sprinkler Controller (24VAC) --> 24VAC Relay Coil24VAC Relay Contacts (NO or NC, depending on your needs) --> 230VAC Power to the Motor Starter Coil230VAC Power Source --> Flow Switch (wired in series with the Motor Starter Coil) --> Motor Starter Coil --> Neutral/Return

Suggested Flow Switch Models (check specifications for compatibility with your setup and water conditions): Dwyer Instruments V6 Flotect Flow Switch

(Paddle type)

Gems Sensors FS-500 Series Flow Switch

(Paddle type)

Fluid Components International (FCI) FLT93L Flow Switch

(Thermal Dispersion type - more expensive)4.

Additional Recommendations Intake Screen/Strainer

Install a good intake screen or strainer on the end of the suction pipe in the pond. This will help prevent debris from clogging the pump and flow switch.

Check Valve

Consider installing a check valve on the pump's discharge side. This prevents water from flowing back into the pond when the pump shuts off, reducing stress on the pump and potentially preventing backflow contamination.

Electrical Safety

All wiring must comply with the National Electrical Code (NEC) and local codes. Use weatherproof electrical boxes and conduit for all outdoor wiring. Properly ground the motor, motor starter, and all metal enclosures. Use a Ground Fault Circuit Interrupter (GFCI) protected circuit for the entire setup. Have a qualified electrician inspect and approve the installation.

Motor Specifications

Note that the data plate SFA rating of 12 amps is the maximum allowable amps that the motor can draw and NOT burn up.

Consult a Professional

If you are not comfortable working with electrical wiring, especially high-voltage wiring, hire a qualified electrician. It's better to be safe than sorry.

Key Takeaways Voltage Compatibility is Critical

Don't directly connect the sprinkler controller to the motor starter. Use a properly rated relay.

Overload Protection is a Must

Use a motor starter with properly sized overload heaters.

Flow Switch Provides Extra Protection

Choose a flow switch appropriate for your water conditions and install it correctly.

Safety First: Follow all electrical codes and use appropriate safety measures.By addressing these issues, you can create a safe, reliable, and protected pond pump system. Good luck! Flag for review

Answer 2

Okay, let's break down your pond pump wiring and control project, addressing the safety, code compliance, and functionality concerns.

Understanding the Situation Existing Setup

An old pond pump was used for irrigation, controlled by a pool timer (likely a Hunter sprinkler system).

New Pump

You have a new 2 HP, 230V single-phase pump with specific ratings (FLA 8.3, SF1.4, SFA 12). It's thermally protected, which is good.

Goal

Use the existing Hunter timer to control a new motor starter with overload protection (heaters) for the pump.

Concern

Protection against a dry pump situation (clogged intake or low pond level).

Addressing Your Questions and Concerns1. Sprinkler Controller to Motor Starter (Voltage Compatibility) Potential Violation

Yes, directly controlling a 230V motor starter coil with a 24VAC (most common sprinkler controller output) sprinkler system is definitely a problem. Sprinkler controllers typically use low-voltage AC (usually 24VAC).

Solution

You'll need an appropriately rated relay or interposing relay. The sprinkler controller output would trigger a 24VAC coil relay. The contacts of that relay would then switch the 230VAC power to the motor starter coil.

Important Considerations

Relay Coil Voltage

Make sure the relay coil voltage matches the sprinkler controller's output (most likely 24VAC).

Relay Contact Rating

The relay contacts need to be rated for the voltage and current required by the motor starter coil (usually printed on the starter). Choose a relay rated higher than the coil rating.

Enclosure

Put the relay and any associated wiring inside a suitable electrical enclosure (NEMA 3R or similar for outdoor use).

Wiring

Follow proper wiring practices, including using appropriately sized conductors and wire connectors.2.

Motor Starter and Overload Protection (Heaters) Essential

A motor starter with properly sized overload heaters is absolutely required. This protects the motor from damage due to overcurrent caused by overload conditions (e.g., a partially clogged impeller, pump working too hard). The thermal protection built into the motor itself is a secondary layer of protection.

Sizing Overload Heaters

Use the Motor's FLA

Use the motor's Full Load Amps (FLA) of 8.3A.

Choose Heaters Based on the FLA

Motor starter manufacturers provide charts that list heater element sizes for specific FLA ranges. Select heaters that fall within the range that includes 8.3A. The overload heaters are designed to trip the starter if the motor draws more than its rated current for an extended period.

Consider Service Factor

The Service Factor (SF) of 1.4 means the motor can handle brief overloads up to 1.4 times its FLA without damage. However, you still size the overload heaters based on the FLA, not the SFA (Service Factor Amps). The SFA (12A) is the maximum current the motor can draw at service factor conditions.3.

Flow Switch for Pump Protection Excellent Idea

Installing a flow switch is a very good way to protect the pump from running dry or cavitating due to a clogged intake.

Types of Flow Switches

Paddle Type

These are relatively simple. A paddle is inserted into the pipe, and when flow occurs, the paddle is deflected, activating a switch. These can be prone to clogging and require periodic cleaning.

Thermal Dispersion Type

These use a heated sensor. When flow occurs, the sensor cools down, activating a switch. These are more reliable in dirty water applications, but they are also more expensive.

Ultrasonic Flow Switch

These send a signal through the pipe wall and sense the returning echo. Requires clean pipe walls and little to no debris.

Installation Considerations

Location

Install the flow switch as close to the pump intake as possible, but downstream of the intake strainer/screen (if any).

Pipe Size

Be sure to get a flow switch that is compatible with your 2" PVC pipe. Some switches have different fittings or adapters available.

Switch Type (Normally Open/Normally Closed)

Normally Open (NO)

The switch is open (no continuity) when there is no flow. When flow occurs, the switch closes. Use this if you want to enable the motor starter control circuit when flow is present.

Normally Closed (NC)

The switch is closed (continuity) when there is no flow. When flow occurs, the switch opens. Use this if you want to disable the motor starter control circuit when flow is not present.

Wiring

The flow switch is installed in series with the control circuit of the motor starter coil. This means that if the flow switch opens (due to no flow), it breaks the circuit to the motor starter coil, shutting off the pump.

Suggested Wiring Diagram with Flow Switch

Topic: Flow switch?