The answer is generally no, it's not permissible and is a very bad idea to combine main and outgoing circuit breakers for different power sources (regular and emergency) in the same fuse box without proper isolation and specific designs to prevent backfeed and safety issues.Here's a breakdown of why and what considerations are needed: Backfeed and Safety Hazards

The biggest danger is backfeeding. If the regular power source fails and the emergency generator kicks in, without proper isolation, power from the emergency source could feed back into the regular power lines. This creates a severe shock hazard for utility workers, can damage equipment, and potentially cause a fire. It can also energize equipment assuming it's dead and posing a safety risk to anyone working on it.

Code Violations

Electrical codes (like the National Electrical Code (NEC) in the US) have strict rules about alternate power sources and preventing backfeed. Combining breakers without proper precautions will almost certainly violate these codes.

Equipment Damage

The voltage and phase characteristics of the two sources might not be perfectly synchronized. Feeding them into each other can damage breakers, wiring, and the floodlights themselves.

The Key: Proper Isolation and Transfer Switching

The safe way to have both regular and emergency power is to use: Automatic Transfer Switch (ATS)

This is the preferred solution. An ATS constantly monitors the regular power source. If it detects a failure, it automatically disconnects the regular power and connects the emergency power to the designated circuits. The ATS ensures that the two power sources are never connected together at the same time.

Manual Transfer Switch

Similar to an ATS, but requires a person to manually switch between the regular and emergency power sources. It still provides the necessary isolation, but relies on human action.

Physically Separate Panels

A less common, but sometimes acceptable, solution is to have entirely separate fuse boxes for the regular and emergency power, with no interconnection whatsoever. The emergency power panel would only feed the emergency-powered floodlights. This requires careful labeling and clear documentation.

In summary



Do not combine the main or outgoing breakers for different power sources (regular and emergency) in the same fuse box without proper isolation. This is extremely dangerous and likely violates electrical codes. Use an Automatic Transfer Switch (ATS) or Manual Transfer Switch to ensure safe switching and prevent backfeed. If using physically separate panels, ensure there's absolutely no electrical connection between them. Always consult with a qualified and licensed electrician for any work involving multiple power sources. They can properly design and install a safe and code-compliant system.

Is it possible to install circuit breakers for two different sources in the same fuse box?

Yes, it is physically possible to install breakers for two different sources in the same fuse box. But it is not electrically safe or code compliant without the correct protective measures such as a transfer switch. Flag for review