A Comprehensive Guide To Submersible Pump Wire

The goal of submersible pump cables is to supply power to submersible underwater pumps. The cables are waterproof, are meant to operate underwater for a prolonged time, and can withstand physical pressure very well. In addition, they are also resistant to abrasion, oil, weather, and chemical impact, making them work in hostile industrial environments. Submersible pump wires are also very flexible because the construction of the well requires them to run in tight spaces.

Characteristics of Submersible Pump Cables

1. Waterproof
2. High-pressure resistance
3. Abrasion resistance
4. Chemical resistance
5. Oil resistance
6. Durability
7. Flexibility
8. UV resistance (for some types exposed to sunlight)
9. Temperature resistance
10. Electrical insulation integrity
11. Mechanical strength
12. Corrosion resistance
13. Non-toxic (safe for drinking water applications)

Submersible Pump Cables Applications

While submersible pump cables are designed for submersible pumps, they are also perfect for various industries when a waterproof, durable cable is needed. Most notably, submersible pump wires are used in irrigation systems and motors, food processing plants, food preserving systems, and mining facilities. In the house, a submersible pump cable in water chlorine injection systems, swimming pools for lighting and other purposes, and aquariums.

Here is the breakdown of some of submersible wire applications:

• Water wells: The submersible pump wire here is used to power water pumps submerged in wells to extract water. There are plenty of different water wells for different conditions.
• Fountains: Wires operate pumps that power water features and fountains.
• Sewage treatment plants: For pumps that operate within sewage and wastewater treatment facilities.
• Aquariums and pools: For submerged filtration systems, cleaning mechanisms, and underwater lighting systems.
• Industrial and mining applications: For dewatering and fluid handling in harsh industrial environments and mines. Submersible pump cables are expected to handle dirty water laden with abrasive particles in mining applications.
• Irrigation systems: To power submersible and surface pumps that manage water distribution and treatment in agricultural settings.
• Food processing plants:  Used in machinery that requires consistent and reliable water circulation and treatment, such as in cooling processes.

Why Are Flat Submersible Pump Cables More Popular?

Using a flat submersible pump cable makes more sense because a flat cable fits the standard design of a submersible pump. Let's look into the construction of flat vs. round wires. A flat cable consists of two conductors and a ground wire, whereas a round cable has three conductors and a ground wire. To supply the water to 2-wire submersible pumps, you only need a two-conductor construction. For this reason, mainly submersible pump flat cables are used in pumps.

There are, however, more reasons for it. One thing is that flat cables are easier to install, especially if the diameter of the well is significant. They are durable and are less prone to wearing off during installation and use because of their physical characteristics compared to a round one.

Even though submersible flat cables are way more popular, there are instances when round cables are preferred. Round cables are used if a pump is 3-wire. 

 Advantages of a flat submersible wire

• Ease of installation
• Space efficiency
• Flexibility
• Less mechanical stress
• Better abrasion resistance
• Suitable for most applications
• Streamlined profile that does not intervene with the water flow
• Less obtrusive and more aesthetically pleasing

Advantages of a round submersible wire

• Better external pressure resistance at extreme depths
• Better tensile strength
• Better EMI
• Better heat dissipation

2 Wire vs 3 Wire Pumps

2 and 3-wire pumps are the most popular across the applications. Here is how to choose between them:

2-Wire Well Pump

• A 2-wire pump has two power wires and one ground wire.
• The motor's starting capacitor is built into the pump's motor; hence, only two wires are necessary for power.

Advantages:

• Simpler installation: With no external control box required for the capacitor or start relay, installation is generally simpler and cheaper. This can be particularly advantageous in tight spaces.
• Lower initial cost: Eliminating the control box can reduce upfront costs.
• Ease of troubleshooting: Fewer components mean potentially simpler diagnostics if issues arise.

Disadvantages:

• Limited accessibility: If a starting capacitor fails, accessing it can be problematic as it is located deep within the well, so you must pull off the pump.
• Service life: The heat generated by the pump motor can shorten the life of the built-in capacitor.

3-Wire Well Pump

• A 3-wire pump typically consists of three power wires and one ground wire. It requires an external control box.
• The external control box houses the starting capacitor and relay. This setup allows easier access to the capacitor and electrical components.

Advantages:

• Ease of maintenance: The external control box makes it easier to service and replace the start capacitor and relay without removing the pump from the well.
• Potentially longer life: Externalizing heat-generating components like capacitors and relays can reduce motor temperature and extend the pump's lifetime.
• Enhanced starting torque: The start capacitor in the control box boosts the motor on startup, which can be beneficial, especially in applications requiring high starting torque.

Disadvantages:

• Complex installation: Requires more wiring and an external control box, which complicates installation.
• Higher initial cost: The additional components (control box, external capacitors) increase upfront costs.
• Space requirements: The control box must be mounted near the wellhead or within a pump house, requiring additional space and potentially more extensive wiring.

Summary

• Choose a 2-wire pump if you are looking for a simpler and potentially cheaper installation and are less concerned about the potential need to pull the pump for servicing the capacitor. An example is residential well installation.
• Opt for a 3-wire pump if you need higher starting torque, prefer easier maintenance access to its electrical components, or install it where the ambient temperature around the pump motor could shorten component lifespans. Examples include industrial applications in hot climates and deep wells.

Things to Know Before Buying a Submersible Pump Wire

• For a submersible pump, you will need a UL-listed Type THW submersible cable. The rating that you need is UL 83. Every UL-rated cable is flexible and protected enough to be put in a submersible pump.
• Most submersible pump wires on the market come with PVC or EPR insulations, and both are perfectly suitable for the conditions they will be exposed to. PVC is a right choice when opting for balance of costs, while EPR is better for specific things like chemical resistance.
• If you are replacing your well pump, there is no need to replace your cables in most cases unless you are also changing the size of the pump or the motor. When replacing the well, the cables should be examined for signs of wear and tear. If there are no prominent signs of wearing off, you can continue to use them with a new well pump.
• Calculate the total length needed from the power source to the pump to ensure you purchase a sufficient amount of cable. Remember that it's better to have a slightly longer cable than needed rather than too short, as splicing submersible cables is not recommended due to the risk of water ingress.
• Heavier cables may be needed for deeper wells to withstand the pressure and mechanical stresses involved. Ensure the cable diameter is suitable for your pump's specifications and well casing.
• Use only connectors that are rated for submersible and watertight applications. Regular connectors may fail underwater, leading to short circuits.

Types Of Submersible Pump Cables

Common types of submersible pump cables on the market are twisted-pair copper cables, flat cables, round cables, and heavy-duty cables.

The basic difference between flat and round submersible pump cables is the most important thing you need to know about submersible pump cables. However, there are more variations of submersible pump cables on the market, and each comes with its applications, even though the difference might be too subtle for a casual user to know on the get-go.

• Thw/Submersible Pump Twisted Copper Cable is suitable for typical, light-duty submersible pump applications. It is best to use this type of cable only when the well is shallow enough so that the maintenance of the wire will not be too expensive if you have to repair or replace it. Twisted copper cable is cheaper than other cables in the range because it does not have extra protection. A twisted copper cable is significantly more affordable than different popular types on the market. The cable is often used in light-duty pumps where external pressures and abrasion are less severe.
• Flat W/GRND THW/Submersible Pump Cable 600V has PVC insulation that gives additional cable protection from abrasion and mechanical impact. When it comes to most submersible pump applications, the durability provided by flat cable is crucial. In deep wells, there is a good chance that the cable will rub against the surface, causing it to wear off quickly, so the jacket provides the much-needed protection. A flat submersible pump cable is several times more expensive than a twisted copper cable but is comparable in price to round and heavy-duty cables.

Flat cable is the most common submersible pump cable because it is easily installed and handled. Flat cables consist of multiple conductors laid side by side, encapsulated in a waterproof and durable insulation jacket. Flat cables are used in residential water wells and irrigation systems.

• Round THW/Submersible Pump Cable 600V is a cable with three conductors and a ground wire. It is perfect for submersible pump applications that require a three-conductor construction. 

Round cables feature conductors twisted together and encapsulated in high-grade insulation material, making them slightly more robust against external abrasions and pressures than flat cables. They typically have a circular cross-section, which might make installation somewhat more challenging in tight spaces than flat cables. Suitable for powering submersible pumps in deeper and narrower wells where cable flexibility and durability against pressure are prioritized.

• Heavy-Duty Flat W/GRND THW/Submersible Pump Cable is a variety of flat cables that have an extra rating for heavy-duty use. The cable is double-jacketed for extra protection. It is good for submersible pumps with extreme conditions because a regular flat cable performs just as well in most heavy-duty applications. It withstands high pressure, high-temperature range, and abrasive conditions. Heavy-duty cable is perfect for industrial applications, deep-water wells, and mines where conditions are harsh, and cables are expected to perform reliably over long periods.
• Other types of cables are sometimes referred under the umbrella term "submersible pump cable" because they are used for related purposes. In our store, these are sprinkler control cables, landscape lighting cables, and UF irrigation cables. UF/Type TWU cables are used for various purposes in irrigation systems, including general ones like lighting and power applications. They are also suitable for direct burial.

At Nassau National Cable, we have built a comprehensive collection of submersible pump cables that can cover every possible need. All of the submersible pump cables in our library fit the latest standards in the industry.

Types Of Submersible Pump Cables Compared

Which Size Wire For Submersible Pumps?

• For 120V Pumps:
• Up to 12 amps: Use 12 AWG
• 12 to 16 amps: Use 10 AWG
• 16 to 24 amps: Use 8 AWG
• Above 24 amps: Use 6 AWG
• For 240V Pumps:
• Up to 15 amps: Use 14 AWG
• 15 to 20 amps: Use 12 AWG
• 20 to 30 amps: Use 10 AWG
• 30 to 40 amps: Use 8 AWG
• 40 to 55 amps: Use 6 AWG
• Above 55 amps: Use 4 AWG

How to Wire a Submersible Pump?

Safety Precautions

• Turn off power: Ensure all power sources are turned off at the breaker box to avoid electrical hazards.
• Check the voltage requirements: Verify that the power supply matches the specifications of the pump.
• Use proper insulation: Use only waterproof and suitable gauge wiring and connectors to handle the load and environmental conditions.

Step-by-Step Wiring Instructions

Step 1: Prepare the Pump and Control Box

1. Unpack the Pump: Carefully remove the submersible pump from its packaging and ensure all parts are accounted for.
2. Install the Control Box: If the pump requires a control box (common for 3-wire pumps), mount it near the well’s head or in another accessible location that remains dry and is protected from the elements.

Step 2: Connect the Pump to the Control Box

1. Measure and Cut the Cable: Measure the distance from the control box to the pump and cut an appropriate length of the submersible pump cable.
2. Strip the Wires: Use wire strippers to expose the copper ends of the wires. Typically, you must strip back about an inch of insulation from each conductor.
3. Connect the Wires to the Pump: Submersible pumps usually have a wiring diagram. Connect the wires according to the diagram, which typically involves connecting the pump wires to the corresponding wires on the cable using waterproof wire connectors. Make sure to connect ground wires properly.
4. Secure the Connections: Use electrical tape and heat shrink tubing to insulate and waterproof all connections thoroughly.

Step 3: Connect the Cable to the Control Box

1. Route the Cable: Run the cable from the pump to the control box. Ensure it is secured and protected against abrasion or kinking.
2. Wire the Control Box: Open the control box and connect the wires from the pump cable to the corresponding terminals inside the control box, following the wiring diagram provided with the control box.
3. Ground the System: Ensure the control box and pump are properly grounded. Connect the ground wires from the pump cable and power supply to the ground terminal in the control box.

Step 4: Connect to Power Supply

1. Prepare Power Cable: Measure, cut, and strip another piece of cable that will run from the control box to your main power supply.
2. Wire to Control Box: Connect the power cable to the appropriate terminals in the control box, matching the live, neutral, and ground wires correctly.
3. Wire to Power Source: Route the other end of the power cable to your electrical panel. Connect it to a dedicated breaker according to the pump's amperage requirements.

Step 5: Test the System

1. Check All Connections: Double-check all electrical connections for correctness and security.
2. Turn on Power: Restore power at the breaker.
3. Test the Pump: Activate the pump using its switch or control mechanism. Use a multimeter to verify that the correct voltage is reaching the pump.
4. Inspect for Proper Operation: Ensure the pump operates smoothly without any unusual noises or vibrations.

Step 6: Final Setup

1. Secure the Cables: Use cable ties to neatly secure the cable along its route to prevent any damage.
2. Seal Entries: Ensure that any point where the cable enters a junction box or control box is sealed against water ingress.

Single Phase 3 Wire Submersible Pump Wiring Diagram

1. From Power Source to Control Box:

• L1 (Line 1, Hot): Connects to the L1 terminal in the control box.
• N (Neutral): Connects to the N terminal in the control box.
• Ground: Connects to the ground terminal in the control box.

1. From Control Box to Pump:

• Red Wire (Start): Connects from the control box to the start winding on the pump.
• Black Wire (Run): Connects from the control box to the run winding on the pump.
• Yellow/Green Wire (Ground): Connects from the ground terminal in the control box to the pump casing.

1. Control Box Internal Wiring:

• The control box will have its own wiring connecting the capacitors and relays to the terminals where the pump wires and power lines attach. This setup is crucial for the starting and running of the pump.

Control Box Wiring Diagram