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Weekly Inspection of ATS

by Brad Keyes, CHSP, on Jan 6, 2021 1:00:00 AM

Q: We got dinged on not doing a weekly inspection of emergency transfer switches. What exactly does one do to inspect an Automatic Transfer Switch (ATS)?

A: According to NFPA 110-2010, section 8.4.1, emergency power supply systems (EPSS), including all appurtenant components, shall be inspected weekly and exercised under load at least monthly. Automatic transfer switches (ATS) are considered an appurtenant of the EPSS so it is required to be inspected weekly. Weekly inspection does not require running of the diesel generator. Running unloaded diesel generators as part of this weekly inspection can result in long-term problems such as wet stacking.

According to Annex Table A.8.4.1(a), of NFPA 110-2010, the weekly inspection of the ATS includes looking at the main contacts to make sure they are clear and clean. Then annually, you are required to actually clean the main contacts.

Check with the manufacturer of the ATS to see if they have specific weekly and monthly inspection.

Topics:Automatic Transfer Switches

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