Commercial buildings often have indoor emergency generators installed in case of a power outage. Several organisations and statutes impose stringent requirements for indoor generators. While many large businesses can afford the extra costs in engineering, construction and maintenance, most homeowners will find these costs prohibitive. While indoor emergency generators have some advantages, the cost outweighs the value unless your indoor generator supports commercial grade square footage and power, according to Gary Barr of Concept Engineering.
National Fire Prevention Association
The National Fire Prevention Association requires that rooms containing indoor emergency generators must minimise damage from flooding yet offer easy access and provide battery-powered emergency lighting. These rooms must contain only the generators to supply emergency power.
Indoor emergency generators must be mounted on 150mm (about 6-inch) foundations solid enough to prevent any sagging that would upset or misalign any connected pipes. These foundations must be isolated to reduce vibration transmission.
Airflow from an outside source must provide the maximum air required by the generator and limit room air temperature to manufacturer specifications. The airflow must come through a two-hour fire-rated system.
Exhaust air must exit through a two-hour fire-rated system, providing flow sufficient to match the incoming air. Exhaust air routing cannot allow the air to re-enter the building. A guard pipe at least 12 inches larger than the air exhaust pipes must contain the pipe if it passes through combustible walls. The requirements for guard pipes passing through combustible roofs increases the pipe size an additional 6 inches.
The National Fire Prevention Association approves spark-ignited, diesel cycle or gas turbine cycle generators for indoor emergency generator equipment. Unpressurized, liquid petroleum products, liquefied petroleum gas or natural/synthetic gas may fuel these generators.
International Fire Code
In section 313.1 the International Fire Code forbids storing, operating or repairing fuelled equipment inside a building unless the building complies with International Building Code section 414.2.4.
The International Fire Code requires the provision of a separately contained space with fire-rated assemblies in a building to store quantities of hazardous materials (such as generator fuel), which isolates the flammable fuel from most of the building.
International Building Code
In Section 414.2.4, the International Building Code requires a one-hour fire-resistance rating for any area containing hazardous materials in buildings with fewer than four floors, and a two-hour fire-resistance rating for buildings with four or more floors. The International Building Code quantifies the maximum amounts of hazardous materials the building can store.
The International Mechanical Code
The International Mechanical Code requires the provision of an exhaust system for all occupied areas where fumes could enter in quantities large enough to impair health or affect safety considerations.