Water motor not starting or not lifting: borewell and sump pumps

A water motor that does nothing has an electrical problem. One that hums but will not run has a capacitor or a jammed impeller. One that runs but lifts no water has lost its prime, is sucking air, has a blocked foot valve or strainer, or — in summer — is pumping from a borewell that has nothing to give. Sort the symptom first, and most of the diagnosis is done.

Before anything else: switch the motor off at its MCB or switch before touching it, the control box or the starter. Motors live in wet places and the combination of water, a damp terminal box and a hand is the one plumbing job that can kill.

Does nothing at all

• MCB tripped or switch off. Reset once. If it trips again immediately, stop — that is a short or a seized motor, not a nuisance trip.
• Starter or control box: a blown fuse, a burnt contact, or the overload relay tripped. There is usually a reset button on a submersible control box; press it once. If it trips again, leave it.
• No supply: a loose connection in the pump's own socket or junction, or the line from the board. Check whether the light in the pump room works; if not, it is the supply, not the motor.
• Auto controller or float switch: if the motor is on a tank-level float or a timer, the controller may simply be telling it not to run. Switch to manual and try.

Hums but will not run

The starting capacitor is the usual suspect on a monoblock, jet or self-priming pump, and on a submersible it sits in the control box above ground. The other cause is a mechanical jam — sand, scale or a bearing — so the motor cannot turn. With the MCB off, some monoblocks have a cap at the back of the shaft that lets you turn it with a screwdriver; if it is stiff, it is jammed. Do not keep pressing the button; a humming motor cooks its winding in a minute or two. Capacitors are not a home repair even though they look simple — they hold a charge after the power is off.

Runs but lifts no water, or very little

Sump and monoblock pumps (suction type):

• Lost prime. Fill the priming plug on top with water, close it, start. If it loses prime every day, air is getting in at a suction joint or the foot valve is leaking back.
• Suction leak. A hairline crack or loose union on the suction line between sump and pump lets air in; the pump churns and lifts nothing.
• Foot valve stuck or strainer blocked with silt — common after the sump is cleaned or after monsoon silt.
• Impeller worn by sand; the pump sounds fine but delivers a trickle.

Borewell submersibles:

• Water level below the pump in summer. The motor runs, the pipe is empty, and the pump is being damaged every minute it runs dry.
• Pipe or joint failed down the bore; the pump lifts water that falls straight back.
• Non-return valve stuck.
• Low voltage. Evening dips across the district leave a submersible without the torque to lift from depth; it runs, draws heavy current and delivers little. If it works in the morning and not at 7 pm, that is your first suspect.

Dry-run protection: not optional here

Every borewell in Nellore should have a dry-run protector on the control box, and a sump pump on a float. Submersibles cool themselves with the water they pump; run dry, they overheat and the winding goes. Across a hot April, a shallow bore can give water for fifteen minutes and then air, and a motor on a timer will sit there destroying itself. A dry-run protector senses the current drop when the pump loses water and cuts it off, and a float in the sump stops a monoblock when the sump is empty. Both cost a fraction of a rewind.

A single-phase preventer or a voltage-cut relay on the control box is worth adding too if your area drops below about 180 V in the evenings.

Borewell or sump: which motor for what

A submersible sits in the bore and pushes water up; it is the only choice for depths beyond what a surface pump can suck, which is most borewells here. A monoblock or self-priming pump sits at ground level and lifts from a sump or shallow tank to the overhead tank; it cannot lift from a deep bore. A jet pump is a middle option for shallow bores. The motor's head (how high it lifts) and flow (litres per minute) must match the bore depth, the tank height and the pipe size — a bigger motor on a low-yield bore just empties it faster and runs dry sooner.

What it costs

Motor install on our rate card is ₹799 for the labour, submersible or domestic pump, with the pump, cable, rope, pipe and fittings at MRP and shown first. A fault on an existing motor is a plumbing visit at ₹299 plus labour, quoted once the technician has found the cause. A rewind on an old motor is often not worth it against a new pump; ask for both numbers before deciding.

When to call

Trips the MCB on every start; hums and does not run; runs and lifts nothing after you have primed it once; any burning smell or a control box that is hot to touch; any wet terminal box. And if the borewell itself is giving less every summer, the conversation is about yield and depth, not the motor.