Okay, this is a tricky problem, but you've provided some excellent information. The fact that the problem seems to jump around circuits, and the observation about the fan slowing down, is key. Let's break down the possible causes and troubleshooting steps

1. Voltage Sag and Line Noise (Most Likely Culprit)
The Problem

Your description of the fan slowing down when the stove/microwave kicks on is a classic sign of voltage sag. This happens when the incoming voltage to your house drops significantly when a large appliance draws a lot of power. This voltage sag can create electrical noise and harmonics that AFCI breakers are very sensitive to. AFCI breakers are designed to detect subtle changes in current flow that mimic an arc fault, and these changes can be triggered by voltage fluctuations.

Why AFCI Breakers Are Tripping

AFCI breakers look for specific waveform irregularities. Voltage sags and surges distort the normal sine wave of the AC current, and that distortion can be misinterpreted as an arc fault.

Troubleshooting and Solutions



Measure Voltage at the Panel

Use a multimeter to measure the voltage at your main panel

while appliances are running (especially the stove, microwave, and dishwasher). Observe if the voltage drops significantly (below, say, 110V) when these appliances are on. This is a crucial first step. Be extremely careful and take all necessary safety precautions when working with electrical panels. If you're not comfortable, hire a qualified electrician. Contact the Property Manager/Owner of the Line

Because the line feeding your house is not owned by the power company, your next step should be to contact the property owner and explain that you are experiencing voltage fluctuations. They will have to contact the power company. Document the trips, appliances and date/times. Let them know that you are worried about damage to your appliances. They can work with the power company to inspect the lines feeding the community property.

Consider a Whole-House Surge Protector (with Voltage Regulation)

A good whole-house surge protector won't just protect against surges, but can also include voltage regulation. These can help smooth out voltage fluctuations. However, these are a band-aid fix, and the underlying voltage sag problem still needs to be addressed. If you go with a surge protector, ensure it has voltage regulation capabilities.

Voltage Monitoring

Consider installing a voltage monitoring device that logs voltage fluctuations over time. This can provide concrete evidence to show the power company. There are smart circuit monitors that integrate with home automation systems that can record such events.

2. Neutral Issues The Problem

A loose or corroded neutral connection can cause voltage imbalances and stray currents that can trigger AFCI breakers. This can be within your panel, at an outlet box, or (more troublingly) somewhere along the shared wiring that feeds your house.

Troubleshooting and Solutions



Check Panel Neutral Connections



WITH THE POWER OFF (MAIN BREAKER OFF), carefully inspect the neutral bus bar in your main panel. Look for loose screws, corrosion, or signs of overheating. Tighten all neutral connections. This is a common source of problems. Check Receptacle Connections



WITH THE POWER OFF (BREAKER OFF), check all the receptacle connections on circuits that are tripping. Make sure the wires are securely connected. Megger Test (Professional Only)

A megger (insulation resistance tester) can be used by a qualified electrician to test the insulation of the wiring in the affected circuits. This can help identify damaged or degraded wiring that could be causing leakage currents.

Hire an Electrician to Check the Entire System

Given the age of the house and the shared power connection, it's possible that a neutral issue exists somewhere upstream in the shared wiring. An electrician can perform voltage drop tests and other diagnostic procedures to track down the source of the problem.

3. Actual Arc Faults The Problem

While less likely given the randomness of the tripping, it's still possible that you have intermittent arc faults caused by damaged wiring or faulty devices.

Troubleshooting and Solutions



Inspect Outlets and Wiring



WITH THE POWER OFF (BREAKER OFF), visually inspect all outlets, switches, and wiring on the affected circuits. Look for signs of damage, such as cracked insulation, loose connections, or charred wiring. Test Appliances Individually

Unplug all appliances on a circuit and then plug them in one by one, monitoring for tripping. This can help isolate a faulty appliance. Consider using an appliance tester (if you have one).

Consider Replacing Problematic Outlets

Old or worn outlets can develop internal arcing. Replacing them can sometimes resolve the issue.

4. AFCI Breaker Sensitivity The Problem

AFCI breakers are known to be overly sensitive at times, especially older models.

Troubleshooting and Solutions



Contact Murray/Siemens Tech Support

Contact Murray/Siemens technical support and describe the problem. They may have specific troubleshooting steps or firmware updates for their AFCI breakers.

Consider Replacing the AFCI Breakers (As a Last Resort)

If all other troubleshooting steps fail, you might consider replacing the problematic AFCI breakers with newer models. Make sure they are compatible with your panel and meet current code requirements. However, do not do this until you've ruled out other issues, as this is often just masking the underlying problem. Do not replace with non-AFCI breakers.

Important Safety Notes



TURN OFF THE POWER

Always turn off the power at the breaker before working on any electrical wiring.

WORK SAFELY

If you are not comfortable working with electricity, hire a qualified electrician.*

FOLLOW CODE

Ensure that any electrical work you do complies with local electrical codes.

In summary, the most likely cause of your random AFCI trips is voltage sag and line noise due to the shared power line. The first step is to measure the voltage at your panel while appliances are running and contact the property owner so they can have the main line inspected. If you are unable to convince them of an issue, you will need to hire an electrician to check the wiring and connections within your house, and test with a megger meter. Flag for review