ATS Panel Wiring diagram generator
Learn the ATS connection for a multi-story residential building. Step-by-step guide for wiring an automatic transfer switch with a generator and main supply.

ATS connection for multi story residential building
Multi-story buildings are wired with ATS whereby the main supply and generator leads to an automatic switch which, in the event of an outage, connects power to the building so that it remains in service.
automatic transfer switch building wiring
A typical ATS (Automatic Transfer Switch) linkage to multi-story residential buildings provides constant power by switching the load between the main utility power supply and a standby generator in the event of a power outage. The ATS wiring diagram incorporates the main supply input, the generator input, and the building distribution system output. In case of mains failure, ATS detects the failure and transfers the load to the generator. The ATS safely loads back once the mains return. In residential buildings with more than one story, ATS are typically fitted to the main LV panel or substation panel, which supplies power to multiple floors via MCBs or MCCBs. This arrangement ensures the safety, reliability, and continuity of service of lifts, lights, pumps, and the required circuits. Proper earthing, cable size, and load balancing are important to building safety and performance.
Work / Installation (Inputs → Outputs)
- Switch OFF all power sources before installation.
- Connect main utility supply (L and N) to ATS input terminals.
- Connect generator supply output to ATS generator input terminals.
- Connect ATS output terminals to the building’s main distribution board.
- Ensure earthing is done properly for both generator and main supply.
- Control wiring: ATS uses sensors to detect power failure and automatically switches between mains and generator.
- Test ATS with simulated power failure before commissioning.
👉 ATS ensures continuous supply to lifts, pumps, lighting, and essential services in multi-story residential buildings.
Testing & Final Adjustments
Once wired, ensure the main utility supply is switched ON, and the ATS is supplying the building distribution board. Then make a simulation of a power failure by switching off the main supply, and the ATS must turn on the generator and place the load on the generator supply within some seconds. On restoration of utility power, the load should be automatically transferred to the main supply when the generator is safely shut off. Test in real operating conditions of building load to maintain stability. Test all the protection devices (MCB, MCCB, RCCB) to ensure they are operating. Check cable endings, earthing, and no overheating. Check synchronization when utilizing an advanced ATS using soft transfer. Label circuits and panels. High reliability of the ATS system in a multi-story building will be guaranteed with regular maintenance and periodical testing.
Frequently Asked Questions - ATS Panel Wiring diagram generator:
What is ATS?
Automatic Transfer Switch that shifts load between main supply and generator.
Why use ATS in buildings?
To ensure uninterrupted power for lifts, pumps, and essential loads.
Where is ATS installed?
At the main distribution panel or LV panel of the building.
How does ATS work?
It senses mains failure and switches load to the generator automatically.
Is ATS manual or automatic?
ATS is automatic but some systems also allow manual mode.
Does ATS need earthing?
Yes, proper earthing is mandatory for safety.
Can ATS handle all building loads?
Yes, if rated properly with correct cable size and capacity.
What rating is needed?
Depends on total load of the building, usually in 100A–630A range.
How to test ATS?
Simulate power failure and observe automatic load transfer.
Is generator auto-start required?
Yes, ATS usually starts the generator automatically during outage.
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