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Minimum Clearances Around Load Banks

An ASCO 6180 performing a load test on a diesel generating set
Load banks apply electrical load to a circuit by converting electrical power to heat. To operate properly, this heat must be removed by providing adequate airflow through the unit. Consequently, proper clearances must be maintained around load banks to avoid overheating and other undesirable conditions. To do so, the following guidelines should be observed.

Airflow Requirements

When operating, a load bank will require a steady airflow at a specified rate to provide full performance. For example, an ASCO 3000 SERIES load bank (low voltage up to 2200 kilowatts) can require up to 12.5 meters/second (~44 cubic feet per second) of airflow under normal operation. Horizontal discharge models require clearances of 1 meter (~3.3 feet) from their intakes and 5 meters (~16.5 feet) from their exhausts. Vertical discharge models also require clear space above the exhaust discharge.

The need for these clearances is two-fold. First, the presence of a wall, corner, other equipment, or any number of other items close to intake or exhaust openings can reduce airflow through the unit, possibly reducing its efficiency and effectiveness and leading to overheating. A second reason is that exhaust temperatures can reach levels that can damage materials and injure people, so sufficient space is required to safely discharge and sufficiently defuse the warm air stream.

Minimum clearances for space surrounding ASCO load banks can be found in the operating manual for each model. The following table lists required clearances for several ASCO product lines and provides links to their manuals. Note that other models may use serial number-specific manuals to provide this information. Contact ASCO for additional information on models not listed here.
Additional AIrflow Considerations

It’s important to ensure that a load bank does not entrain warm air from adjoining equipment such as other load banks, engine-generator sets, transformers, HVAC units, and other heat-producing equipment. It is also important to ensure that the hot exhaust is not recirculated to its intake or the intakes of adjoining units. Where this could occur, partitions may be needed to prevent the inadvertent exchange of hot air flows.

For indoor applications, where load banks and other devices are housed in an equipment room, the total airflow through the room must be sufficient to maintain ambient temperatures within the operating range of load banks. Where ducts direct airflow to and from load banks, ductwork must be sized, and turns must be of sufficient radii, to avoid restricting airflow rates. Exhaust ductwork may also require insulation to avoid raising ambient temperatures above desired levels and to protect people from hot duct surfaces.

Addition Information

Interactive 3D Models of ASCO Load Banks (Click Healthcare > Regional > Load Banks > ASCO Model 2805)
ASCO Technical FAQ Video: What are Some of the Factors that Could Cause an Overtemperature Condition?

ASCO White Papers:
Understanding Load Bank Circuits
Load Bank Rating Factors
Resistive, Inductive, and Capacitive Load Bank Elements
Maintaining Load Banks for Reliability and Longevity


For additional information, contact ASCO Customer Care.