Okay, let's break down the requirements for a disconnect at your guest house. I am not an electrician, so the following is for informational purposes only and does not constitute professional advice. Consult with a licensed electrician to ensure your installation complies with all applicable codes and is safe.Key Considerations



NEC (National Electrical Code)

The NEC is the standard electrical code in the US, and your local jurisdiction likely adopts and modifies it. The specific edition of the NEC adopted by your jurisdiction is crucial.

Local Amendments

Your city or county may have amendments to the NEC, adding or modifying requirements.

Building Inspector

The building inspector has the final say on whether your installation is compliant.

General Guidance Based on Common NEC Practices



1. Disconnect at Guest House (Likely Required)



NEC 225.31 (Disconnecting Means)

This section generally requires a disconnecting means at each building or structure. The purpose is to provide a readily accessible way to de-energize the entire guest house for maintenance, emergencies, or by first responders.

NEC 225.32 (Location)

The disconnecting means must be installed at a readily accessible location either inside or outside of the guest house, and nearest the point of entrance of the feeder conductors. Often, this means right next to the MLO panel inside or directly adjacent to the panel on the outside.

NEC 225.33 (Maximum Number of Disconnects)

Generally, you can only have up to six switches or circuit breakers serving as the disconnecting means. This isn't usually an issue in a small guest house situation.

2. Exceptions (Less Common, Needs Scrutiny)

The NEC does have exceptions, but they are typically for very specific scenarios and are often difficult to apply in a residential guest house situation. The most likely exception (but still unlikely) would be if the detached building is a very small structure with very limited loads, and is under the same management. These exceptions are not typically applicable to a guesthouse with a 125A panel.

3. Grounding and Bonding



Ground Rod(s)

Yes, you will need at least one (and possibly two, depending on the NEC edition and local rules) ground rod driven at the guest house. The ground rod is connected to the grounding busbar in the MLO panel.

Grounded Conductor (Neutral)

The neutral conductor from the main house must be run with the feeder conductors to the guesthouse. The neutral is bonded to the grounding busbar at the guesthouse panel at the

first means of disconnect. After that, the neutral must be isolated from the enclosure. Equipment Grounding Conductor (EGC)

A separate equipment grounding conductor (EGC) must be run from the main panel to the guest house panel. This is usually a copper wire. It is used to provide a low-impedance path for fault current to return to the source, tripping the circuit breaker.

In summary

A separate disconnect is required at the guest house.

Key Takeaways & Recommendations


Hire a Licensed Electrician

Cannot stress this enough. They know the local codes, can perform the installation safely, and will ensure it passes inspection.2.

Consult with the Building Inspector

Talk to the local building department before you start any work. They can clarify any local amendments or specific requirements they enforce.3.

Plan for the Disconnect: Plan to have a readily accessible disconnect at the guest house. This will almost certainly be required.Remember, electrical work is dangerous. Always prioritize safety and compliance.* Flag for review