Installing a Bore Pump

A bore pump installation is a lifting job, an electrical job and a plumbing job at once, at the top of a hole that may be a hundred metres deep. Drop something and it is not coming back. Splice a cable badly and you will be pulling the whole assembly out again.

Plan it, gather everything before you start, and do not do it alone.

Get the sizing right first. Setting depth, total dynamic head and the bore’s yield must be settled before installation day — see Sizing a Bore Pump. All fixed electrical work must be carried out by a licensed electrician under AS/NZS 3000.

What you will need

• The pump and its matched control box. The RM-BORE2 ships with 40 m of SAA-certified cable and a control box containing the start components — the box is part of the pump, not an accessory.
• Riser pipe (galvanised, poly or stainless) rated for the pressure and the hanging weight.
• Safety rope of stainless or high-strength polypropylene, rated well above the assembly weight.
• Torque arrestor, cable ties or clips, and a submersible splice kit if extending the cable.
• Non-return valve, bore head or well seal, pressure gauge.
• Insulation resistance tester (megger), multimeter, water level meter.
• At least two people, and lifting gear appropriate to the depth. A 4” pump on 60 m of riser full of water is a serious weight.

The RM-BORE2 itself weighs 24.2 kg net and comes in a 108 cm carton — long, awkward, and best handled by two.

Step 1: Check the bore

Before anything goes in the hole:

• Re-measure the standing water level. Aquifers move seasonally, and the driller’s figure may be years old.
• Check the bore is clear. Lower a dummy weight of the same diameter and length as the pump on a rope, down to the intended setting depth. If it snags, the pump would too. Better to find out with a weight.
• Confirm casing diameter at the top and, if possible, further down.
• Check for sediment at the base, and adjust the setting depth to keep 2–3 m of clearance.

Step 2: Test the pump before it goes down

Two minutes now saves a day later.

1. Insulation resistance test. Megger each phase conductor to earth. A healthy submersible motor reads in the tens of megohms or higher. A low reading means moisture in the motor — do not install it.
2. Winding resistance. Check against the manufacturer’s figures with a multimeter.
3. Turn the shaft by hand where accessible. It should rotate freely.
4. Brief power test. Only if the manufacturer permits it, and only for a second or two — a submersible motor is water-cooled and will overheat in air almost immediately.

Record the readings. They are your baseline for any future fault-finding.

Step 3: Assemble

Non-return valve. Most submersibles include one integrally. If yours does not, fit one directly above the pump. On deep settings, additional check valves at intervals up the riser prevent the full column of water hammering back down on shutdown.

Riser pipe. Connect the first length to the pump discharge with thread sealant and tighten properly. Every joint carries the weight of everything below it plus the water inside.

Safety rope. Attach to the lifting points on the pump body, never to the cable or the riser. Run it the full length to the surface with a little slack, and secure it at the bore head. If a riser joint ever fails, this rope is what stops the pump disappearing.

Torque arrestor. Fit above the pump. A submersible motor twists sharply on start-up, and without an arrestor that torque works on the joints and can rub the cable against the casing.

Cable. Run it alongside the riser with a little slack — never taut — and secure it with clips or tape every 2–3 m. Keep it clear of the casing wall.

Splicing the cable

If the setting depth plus the run to the control box exceeds the 40 m supplied:

• Use a proper submersible splice kit — heat-shrink or resin-filled, rated for permanent immersion.
• Follow the kit instructions exactly, including cure times.
• Stagger the joints in each conductor so they are not all at the same point.
• Test insulation resistance after splicing and before lowering.

Insulation tape is not a splice. It will fail, and the failure will be at the bottom of the bore.

Step 4: Lower it in

Take it slowly.

1. Lower steadily, supporting the weight at all times. Never let the assembly drop under its own weight.
2. Add riser lengths as you go, tightening each joint fully.
3. Feed the cable and safety rope down together with the riser, clipping as you go.
4. Count and record the lengths. You need to know exactly how deep the pump sits — for the record, and for future work.
5. Watch for resistance. If the assembly stops descending, do not force it. Withdraw, find the obstruction, then continue.

Stop at the planned setting depth: below the pumping water level with margin, and clear of the bottom.

Step 5: Finish the bore head

• Support the riser at the surface with a bore head plate or well seal that carries the full weight of the assembly.
• Seal the top of the casing to keep surface water, debris and vermin out. Contaminated surface water entering a bore is both a pump problem and a water quality problem.
• Bring the cable out through a proper gland.
• Fit an isolation valve, a pressure gauge and a discharge point at the head. The gauge lets you see what the pump is doing without guesswork.

Step 6: Wire the control box

The control box holds the start capacitor and the motor’s overload protection. It must be:

• The box supplied with the pump. These are matched to the specific motor. A substituted box will not protect it correctly.
• Mounted in a dry, shaded, ventilated position — not in direct sun, not in a sealed enclosure. Heat is the enemy of capacitors.
• Wired by a licensed electrician, on an RCD-protected circuit, correctly earthed, with terminals torqued to specification.

Have the electrician confirm supply voltage at the box under load. Voltage drop from a long run makes motors draw more current and run hotter, and is a leading cause of premature submersible failure.

Step 7: Commission

1. Open the discharge valve before starting. Never start a bore pump against a closed valve.
2. Start briefly and confirm the pump is moving water and current draw looks correct.
3. Run and observe. Water will run cloudy at first, then clear as the bore settles.
4. Measure drawdown with a water level meter while pumping. Watch it stabilise. If the level keeps falling and does not settle, stop — the pump is outpacing the bore’s yield, and you need a lower flow rate or a restricted discharge.
5. Measure actual flow with a bucket and stopwatch, or a flow meter.
6. Check current draw against the motor’s rated full load current.
7. Record everything: setting depth, standing water level, pumping water level, drawdown, flow, current, pressure and date. This record is what makes diagnosing a problem in five years’ possible.

Protecting the investment

• Run-dry protection. A level probe, flow switch or controller with dry-run detection. Bore pumps fail from running dry more than from anything else.
• Do not cycle it hard. Frequent starts overheat submersible motors. A storage tank plus a level switch — pump into the tank, pressurise from the tank — is far kinder than starting and stopping on demand.
• Leave it submerged. A bore pump is cooled by the water around it.
• Check annually. Standing water level, drawdown, flow and current, compared against your commissioning record. A drift in any of them is early warning.

When to bring in a driller

Do it yourself only if you are properly equipped and the bore is shallow. Call a licensed bore contractor when:

• The bore is deep enough that the assembly weight exceeds what you can safely handle.
• The casing condition is unknown or the bore has a history of collapse.
• The existing pump is stuck and needs extraction.
• Your state requires licensed work on bores — many do. Check before you start.