Installation Guide8 min readMarch 7, 2026

What to Expect: The Generac Generator Installation Process in the San Bernardino Mountains

Many homeowners in Running Springs and Cedar Glen wonder what a full Generac installation actually involves. Here's our complete step-by-step walkthrough — from site assessment to final startup.

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Installation Day: No Surprises

One of the most common questions we hear from homeowners in Running Springs, Cedar Glen, and Green Valley Lake is: "What does the installation actually involve?" It's a fair question. A Generac standby generator installation is a multi-trade project that involves concrete work, gas plumbing, and electrical work — all of which must meet local building codes and pass inspection. At Mountain Top Generator, we handle every aspect of the installation in-house, so you never have to coordinate multiple contractors or wonder who is responsible for what.

Step 1: Free Site Assessment

Every installation begins with a free on-site assessment. Our team visits your property to evaluate the best location for the generator (typically on the side or rear of the home, away from windows and doors per code requirements), assess the gas supply capacity, review your electrical panel, and determine the appropriate generator size for your load requirements. In mountain communities, we also account for site-specific factors like slope, drainage, snow load, and access for service.

Step 2: Permitting

Mountain Top Generator pulls all required permits from San Bernardino County before any work begins. This protects you as the homeowner and ensures the installation is fully code-compliant. Permit requirements in unincorporated mountain communities like Crestline and Twin Peaks include electrical, mechanical, and sometimes plumbing permits depending on the scope of work.

Step 3: Concrete Pad Installation

The generator must be mounted on a level, stable concrete pad. Our crew pours a code-compliant pad sized to the specific generator model, with proper clearances on all sides. In areas with significant freeze-thaw cycles — common at higher elevations like Running Springs and Green Valley Lake — we use reinforced concrete to prevent cracking.

Step 4: Gas Line Installation

Our licensed gas fitters run a dedicated gas line from your meter or propane tank to the generator location. Line sizing is calculated to ensure adequate BTU supply for the generator's full load, without compromising supply to your home's other gas appliances.

Step 5: Electrical Transfer Switch Installation

The automatic transfer switch (ATS) is the brain of the system. It monitors utility power continuously and signals the generator to start when an outage is detected. Our licensed electricians install the ATS at your main electrical panel, wire it to the generator, and configure it for your specific load requirements. For whole-home systems, we install a whole-house transfer switch that covers every circuit.

Step 6: Generator Startup and Testing

Once all components are installed and inspected, our technician performs a full commissioning: starting the generator, testing the automatic transfer function, configuring the Mobile Link™ WiFi monitoring, and walking you through the system's operation and maintenance schedule. We don't leave until you're fully confident in your new system.

From assessment to final startup, most installations are completed in one to two days. Call Mountain Top Generator at (909) 414-2803 to schedule your free site assessment today.

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© 2026 Mountain Top Generator · 25266 CA-18, Crestline, CA 92325 · Licensed & Insured · Authorized Generac Dealer