Answering Your Water Pump Questions

with RPS Engineer Mike

April 18, 2024

How is a well pump wired?

Electrical wiring is often the part of a submersible well pump install that folks feel least comfortable with. If you don’t have a lot of experience with electricity, it can feel dangerous to strip and crimp wires together, or to install pressure switches or starter boxes. Never fear, hopefully the following pages break down each component of our DIY kits wiring install into easily accessible pieces.

When you receive a submersible well pump from us, some key electrical steps will include:

Checking the current breaker box fuse you plan to use as a power input to your pump. You’ll want to consult the following table to determine what an acceptable circuit breaker rating is in amps. If you’re upgrading to a larger HP well pump, you may need to swap out your circuit breaker.

Table 1: Circuit Breaker Rating by Pump HP

HP	Volts	Circuit Breaker Amps	Standard Fuse Amps	NM-B Wire Gauge Necessary
½ HP	110V	15	15	14ga
½ HP	220V	15	15	14ga
¾ HP		20	20	12ga
1 HP		25	25	10ga
1 ½ HP		30	30	10ga
2 HP		30	30	10ga
3 HP		45	40	8ga
5 HP		70	60	4ga

2. Splicing your pump wire properly. Every pump kit comes with a splice set that you will use to connect the wire pigtail coming out of the pump with your own pump wire or wire purchased from us. Full diagrams are available on page 15 of our User Manual, which is available for free to customers that take our sizing quiz. In overview however, you’ll need to strip your wire outer jacketing, crimp both sets of wires by color, and then shrink the watertight tubing we provide over the crimp with a heat gun or lighter.

3. You would then ground the starter box we sent to you, first making sure to turn off any power at the breaker box you will be using to install. This is a priority for all following steps. You’ll see a set of terminal screws labeled L1, L2, R, Y, B, as well as a lower grounding nut. Your pump wire would have four wires, with the green being the designated ground that would be screwed to the grounding nut. There will also need to be a second customer provided NM-B wire from the breaker box whose grounding wire would need to be grounded. Strip any insulation, you can also use an optional fork terminal to secure the ends of the ground wires to the grounding nut.

Diagram 1: Wire Grounding

4. You would then finish wiring into the starter box. For the pump side, you would wire the red, yellow and black wires into the corresponding R, Y and B screws. On the other side from your NM-B wire you would have a black line and another colored line (often red, black or blue) that would be wired into the L1 and L2 terminal. It doesn’t matter which line goes where, both wires are ‘hot’.

Diagram 2: Starter Box Wiring

5. If using a pressure switch, which is standard for household applications, you would want to wire it in between your breaker box and starter box. From your starter box, you would wire from L1 and L2 to the T1 and T2 terminals in the pressure switch (the two central terminals). From the breaker box, you would wire to the L1 and L2 present on the pressure switch.

Diagram 3 - Pressure Switch Wiring

6. If you’re not wiring from a breaker but rather to a generator, the wiring can go straight to the pressure switch or starter box L1 and L2. You will need to cap the neutral wire, which is opposite the ground wire (normally green), and use the other two hot wires. For wiring into a GFCI outlet, you can either hardwire from your NM-B wire or splice into a 220V NEMA power cord. We recommend hardwiring to prevent any tripping hazards.

If you still have questions about wiring, we’d love to chat more with you. Again, electricity can be scary, and rule number one is always to turn off any breakers you’ll be working with. Besides that, you’ll want a multimeter to troubleshoot voltages. Still nervous? Call us at (855)-560-5670 or email us at help@ruralpowersystems.com. We can walk you through each step of the process, both pre and post-sale. Since we don’t make commission, there’s no pressure to buy right away, we just go at your pace! We hope to hear from you soon!

Filed in: House well system, Submersible well pump, Water pump

Previous article What burns out a well pump?

Next article How deep should a well pump be?

Take the Next Step to Water Independence

Pump Sizing Wizard

** 83% complete in under 2 minutes

Get a $50 Coupon

Start Sizing

FREE 10 Minute Sizing Quick Sizing Call

Get a Quote Same Day from RPS Engineer

📞 Call 855-560-5670