Commercial and industrial · 30 kW to multi-MW
Commercial generator installation for buildings that can't go dark.
A commercial generator installation covers the generator set, transfer switches or paralleling gear, the fuel system, foundation and rigging, feeders, permits and an acceptance load test. The NEC article your loads fall under (700 emergency, 701 legally required or 702 optional standby) sets the transfer time, testing and fuel rules.
Example commercial scopeNEC 702
- Output
- 150 kW · 480/277 V · 3Ø
- Fuel
- Diesel · sub-base tank
- Classification
- NFPA 110 Level 1
- Transfer
- 2 × ATS · 10 s emergency
- Enclosure
- Sound-attenuated, weather
- Testing
- Load bank at startup
Illustrative only. Your classification comes from the engineer of record and the AHJ.
| System type | NEC article | What it serves | Transfer time |
|---|---|---|---|
| Emergency | Art. 700 | Egress lighting, fire alarm, life safety loads required by code | ≤ 10 s |
| Legally required standby | Art. 701 | Loads a code or authority requires, like smoke control, sewage, some communications | ≤ 60 s |
| Optional standby | Art. 702 | Business continuity: servers, refrigeration, HVAC, production | Set by owner |
What we handle
- Load study review and sizing with the engineer of record, or a design-build scope where none exists.
- Generator set, enclosure and sub-base or remote fuel tank, with the fuel class sized to the required run hours.
- Automatic transfer switches, bypass-isolation switches and paralleling switchgear.
- Foundation, crane and rigging plan, and site access for delivery.
- Feeders, grounding, annunciator and remote monitoring.
- Permits, utility coordination, air permit review, and the acceptance test with a resistive load bank.
Who we build for
General contractors who need a generator sub that reads the spec, prices the addenda and shows up for the pre-bid. Facility managers replacing an old set. Owners of medical offices, assisted living, water and wastewater plants, cold storage, telecom huts and small data rooms.
Send drawings, the spec section and the bid date. You get a scope letter with clarifications and exclusions spelled out, not a single number on a napkin.
Commercial generator questions
Does a commercial generator have to meet NFPA 110?
When the generator serves emergency or legally required loads under NEC Articles 700 or 701, the local authority will usually enforce NFPA 110: Level 1 or Level 2 classification, a 10-second start for emergency systems, a fuel supply rated for the required hours, and monthly testing under load. Optional standby systems under NEC 702 for business continuity usually aren't held to it, though many owners follow it anyway.
How long does a commercial generator installation take?
Plan from the equipment lead time backward. Larger diesel sets and paralleling gear have run many months from order to delivery, and permitting, utility coordination and any air permit run alongside. Site work, setting and wiring are usually days to a few weeks. We quote current lead time with the proposal instead of guessing here.
Diesel or natural gas for a commercial generator?
Diesel carries its fuel on site, starts and accepts load fast, and is the usual choice for emergency and legally required systems. Natural gas avoids fuel storage and refueling, which suits optional standby for business continuity, but depends on the gas utility staying up and needs adequate supply pressure for the size. Some sites use bi-fuel. The code requirements for your load decide it more than preference.
Do commercial generators need an air permit?
Sometimes. Stationary diesel engines fall under EPA rules for emergency engines, and several states require a permit or registration above certain sizes or run hours. We check the state and local rules for your site during proposal, since it can affect fuel choice and testing hours.
What testing does a commercial generator need after install?
At minimum: an acceptance test with a load bank or building load at startup, then monthly exercise under load and annual load testing where NFPA 110 applies. We hand over the startup report and test records for your files and your inspector.