December 10, 2025

Generator Sizing for Commercial Buildings: kW, Runtime, and Transfer Switch Selection

Undersized generators trip on inrush. Oversized ones waste capital and run wet. Here's how we size standby plants for office, retail, and medical occupancies.

We work commercial electrical full-time, and that means we see the same problems repeat. This article walks through what we've seen on recent jobs, what we tested, and what we ended up replacing.

What it looks like in the field

The symptom usually shows up at the panel before anyone notices a problem with the load. By the time tenants complain, the issue has been measurable for weeks.

How we diagnose

Meter readings before assumptions. IR scans are useful but they aren't the whole story — we always confirm with a torque audit and ground-resistance measurement before we recommend replacement.

What we replaced

Across the last 200 commercial service calls in this category, the most common parts were breakers (specific revisions), connectors, and contactors on RTU disconnects. We carry those on the truck.

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Apr 2026

What an IR Scan Actually Catches — And What It Misses

Thermographic scans are oversold. Here's what we've actually caught in the last 200 commercial scans, and the three things you still have to test with a meter.

Mar 2026

Planning a JEA-Coordinated Service Upgrade Without Killing Your Tenants

Coordinated outages with JEA take 6–10 weeks to schedule. Here's how we sequence the temp service, transition, and re-energization so tenants only see one overnight outage.

Feb 2026

The Real Math on LED Retrofits (and Why Most Rebate Estimates Are Off)

Utility rebates look great on paper. We ran the numbers on twelve recent retrofits — here's the gap between projected and realized savings, and why.

Jan 2026

Do You Have Capacity for EV Chargers? Probably Not Without a Demand Study.