Generator Annual Load Test

Q: My client installed a generator in a Phase 1 project that does not and will not for some time be able to meet the requirements for the 30% load during the monthly test due to low current loading. As I understand it, 8.4.2.3 in NFPA 110 allows you to do the monthly test as is and do a supplemental annual test yearly as outlined which would then meet the requirement for the monthly test. Is that the proper interpretation as the generator will not meet the 30% requirement until some unknown future date?

A: Yes… section 8.4.2.3 of NFPA 110-2010 is the correct reference when any one of the monthly tests cannot meet the requirement for at least a 30% load. The annual test must be conducted within 12 months of the first monthly test that was incapable of meeting the 30% load requirement, and then no more than 12 months from the last annual load test.

Your client should continue to conduct the monthly load tests (not less than 20 days and not more than 40 days) with the available load. For the annual load test, a supplemental load (i.e. load bank) of not less than 50% of the nameplate kW rating for 30-minutes and a supplemental load of 75% of the nameplate kW rating for 60-minutes must be conducted, for a total test of 90 continuous minutes.

The cool-down period for the generator is not part of this 90-minute test.