Okay, this sounds frustrating! Let's break down the troubleshooting steps. Since the problem affects both the tenant's space and the customer's garage, and the outage involves lighting, outlets, and garage door opener, we need to think about shared circuits and common points of failure.Here's a plan

1. Verify the Basics Again (even if you think you did):
Main Breaker Panel (Crucial)

Go back to the main breaker panel. A single tripped main breaker feeding those three circuit breakers could be the issue.

Ensure all main breakers are fully engaged. Sometimes, a breaker looks on, but it's actually tripped internally. Flip all main breakers fully OFF and then firmly back ON. This resets them definitively. This is especially important if the tenant saw a light go out elsewhere. A main breaker tripping will cause a widespread outage.2. Expanding the Scope: More Information Needed What Exactly Does Work? You mentioned the water heater works, but get a VERY clear list of everything that works and doesn't work. Be specific. Which outlets work? Which lights work? Knowing the pattern of what's affected helps narrow down the potential circuit. Does ANYTHING in the garage work? Meter

Does the electric meter indicate power usage.

How are the units metered? Are the units under different electric meters, or are they under one? Photocells and Timers

Any light switch photocells or timers?

3. The GFCI Hunt (Continued)



Systematically Search

The customer needs to thoroughly search for GFCIs, not just look behind boxes. GFCIs could be in the following locations: Garages (especially near sinks or hose bibs). Bathrooms (even if they seem far from the affected circuits). Kitchens (especially near sinks or countertops). Outdoors (front porch, back porch, etc.). Basements or crawl spaces.

Use a GFCI Tester

If the customer is reluctant to search meticulously, suggest they purchase a simple GFCI tester at a hardware store (they're inexpensive). Plug the tester into every outlet. The tester will trip the GFCI if present, and the customer will at least know they found one.

Neighbor's Unit

Ask the customer to check with the neighbor (if possible) to see if they have GFCIs and if any of them are tripped. Since the issue affected the lobby light, there might be a tripped GFCI in a common area.

4. Wiring Diagrams (If Possible)



Check for Old Wiring Diagrams

An old house might have some wiring diagrams hidden somewhere. This would be immensely helpful in tracing circuits.

Track the Cables

Where does the wiring run to? If you could follow the cables, you could see where things meet.

5. The "Shared Neutral" Hypothesis



Multiple Circuits on One Neutral

In older homes, it's sometimes possible (though not to modern code) that multiple circuits share a single neutral wire. If that neutral connection becomes loose or broken, it can cause a cascade of problems on multiple circuits, even if the hot wires are on different breakers.

Testing for Shared Neutrals

This requires more advanced electrical testing and is

NOT something a homeowner should do. It would involve checking voltage between different circuits and the neutral. This is where a qualified electrician is needed.6. When to Call a Professional (Highly Recommended)



If you find nothing after a thorough GFCI search and breaker reset

It's time to call a licensed electrician. Electrical troubleshooting can be dangerous, especially in older homes with potentially outdated wiring.

If you suspect a shared neutral

This definitely requires professional attention.

If you notice any signs of burning, melting, or corrosion on wiring or electrical components

This is a serious safety hazard.

Why a Professional is Often Needed



Experience

Electricians are trained to quickly identify common electrical faults.

Tools

They have specialized tools like multimeters, circuit tracers, and amp clamps to diagnose problems accurately.

Safety

They know how to work safely with electricity and avoid shocks or creating further damage.

Code Compliance

They can ensure that any repairs meet current electrical codes.

Important Considerations for the Customer



Explain the Troubleshooting Process

Let the customer know that troubleshooting electrical issues can take time and may involve some detective work.

Emphasize Safety

Stress the importance of not attempting repairs themselves if they are not qualified.*

Document Everything: Keep a record of what you've tried and any observations you've made. This will help the electrician diagnose the problem faster.Let me know if you get any more information, and I can help refine the troubleshooting steps. Good luck! Flag for review