The Short Answer
A permanently installed generator almost always requires engineering. The scope spans electrical design (transfer equipment, distribution, and integration with the service), fuel system design (natural gas or on-site fuel storage), and structural design (the pad or roof support and anchorage). Because generators involve life-safety and standby power, multiple permits — electrical, mechanical, and often structural — are typically required, with stamped drawings from licensed engineers.
Electrical Engineering
The electrical scope is central. Engineers design how the generator connects to the building through an automatic or manual transfer switch, determine which loads the generator serves (whole-building, emergency, or optional standby), and integrate the generator into the one-line diagram and distribution. Sizing the generator to the intended load, coordinating overcurrent protection, and ensuring safe transfer between utility and generator power are all part of the electrical design.
Fuel System
Generators need a fuel source. Natural gas units require a gas connection sized for the generator's demand and coordinated with the utility and building gas system. On-site fuel storage (diesel or propane) adds tank sizing, spill containment, clearances, and code requirements for fuel handling. The fuel system design ensures reliable operation and code compliance, and it coordinates with the mechanical and plumbing scope.
Structural Pad and Anchorage
A generator is heavy equipment that must be supported and anchored. Ground-mounted units typically sit on an engineered concrete pad; rooftop or elevated units require verification that the structure can carry the weight. In either case, the equipment must be anchored to resist wind and, where applicable, seismic forces so it stays in place and operational. Our structural engineers design the pad or support and the anchorage, coordinating directly with the electrical and mechanical design.
Location, Clearances, and Noise
Generator placement involves multiple considerations: required clearances from the building and property lines, exhaust and emissions routing, sound attenuation for occupied areas and neighbors, and access for maintenance. These factors are coordinated among disciplines and with the site and civil design when the generator sits outdoors. Zoning and local rules can affect placement, which the design accounts for.
When Do You Need This?
Engineering is needed for any permanently installed standby or emergency generator — commercial facilities requiring backup power, life-safety systems, data and medical facilities, and critical operations. Portable generators are different, but fixed installations tied into the building's electrical system require the coordinated electrical, fuel, and structural design described above. Send us your generator and load information and we'll define the scope.
Frequently Asked Questions
What permits does a generator require?
Typically electrical and mechanical permits, and often a structural permit for the pad or support. Requirements vary by jurisdiction; the building department's checklist governs, and we prepare the stamped drawings needed.
How is the generator size determined?
By the loads it must serve. Engineers total the connected standby loads and starting characteristics, apply the appropriate methods, and size the generator and transfer equipment accordingly.
Do you handle both the electrical and structural design?
Yes. With electrical, mechanical, and structural engineers in-house, we coordinate the transfer equipment, fuel system, and pad or support anchorage as one integrated design.