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Md Jony Islam Author
Md Jony Islam
CalculatorToolsProjectExpert
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Małgorzata Koperska, MD Steven Wooding
Last updated: August 9, 2025

Day Night Sensor with Contactor Wiring Guide

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Components List

Single phase Light

Single-Phase LED Light

Energy-efficient LED light for single-phase supply

Single phase Light

Well Light Holder

Recessed light holder typically used in ceilings/walls

Single Phase DP MCB

Single Phase DP MCB

Double Pole Miniature Circuit Breaker for single-phase supply

Single Phase Contactor

Single Phase Contactor

Electromagnetic switch designed for controlling single-phase electrical loads

[single-phase-contactor]
Day-Night Sensor

Day-Night Sensor

Light-sensitive switch that turns circuits on/off based on ambient light

[day-night-sensor]

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Day Night Sensor Using Contactor wiring

Automatic lighting control using a day-night sensor with a contactor for high-load circuits, ensuring safe, efficient, and hands-free operation.

two way light switch wiring diagram

Feel like controlling one light using two separate places? The ideal solution is the use of the two-way switch wiring system. This circuit can be installed between staircases or very long hallways and is done using two SPDT switches and two traveler wires to give you the ability to conveniently turn on the light from either end. This is how this works.

Formula & Table Summary:

 Lighting Load Control = (Sensor Output× Contactor Coil) → Load Terminals 

day night sensor wiring diagram

As the connected load is more than the direct switching capacity of the sensor, a day night sensor is used with the wiring of a contactor. The sensor judges on the amount of ambient lights and when the darkness sets in, it energizes the contactor coil. This switches the main contacts of the contactor to apply power to the lighting system. The sensor, when the light goes on the sensor turns off the light. In the morning the sensor shuts off the coil, opening the contacts and shutting off the lights. The approach is suitable when used with street lighting, car parks, yards and expansive outdoor lighting installations. A contactor operating the sensor remains reliable, prolongs the operating life of the sensor, and protects it against high levels of current. Proper connection would be that live and neutral supply gets to the sensor, the sensor contact would go to the contactor coil, the lighting circuit would go through the contactor load.

automatic light switch circuit

ComponentInput VoltageOutput ControlMax Load Capacity
Day Night Sensor220V ACCoil Activation≤ 5A direct load
Contactor220V CoilLoad Switching20–100A
Lighting Circuit220V ACDepends on lamps

Frequently Asked Questions - Day Night Sensor Using Contactor wiring:

What is a day night sensor with contactor?

A system where the sensor triggers a contactor to switch large lighting loads automatically.

Why use a contactor with a day night sensor?

To handle high current loads that the sensor cannot switch directly.

What voltage does the contactor coil use?

Commonly 220V AC or 24V AC/DC depending on design.

Can I connect lights directly to the sensor?

Only if the load is within the sensor’s rated capacity.

Is wiring complicated?

No, but proper safety precautions and wiring sequence must be followed.

Where is this setup used?

Street lighting, parking lots, and industrial outdoor lighting.

Does it save energy?

Yes, lights only operate when needed, reducing energy consumption.

Can I adjust light sensitivity?

Yes, most sensors have adjustable lux settings.

Is maintenance needed?

Occasional cleaning of the sensor lens and checking connections is advised.

What happens if the contactor fails?

Lights may stay on or off until the contactor is replaced.

Md Jony Islam

Md Jony Islam

CalculatorToolsProject

Founder of Earthbondhon.com

a free online tools website designed to make everyday and engineering-related calculations easier for students, professionals, and hobbyists. The site offers a wide range of basic calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators.