I just use an ATS like this: https://www.apc.com/us/en/product/AP4421A/apc-netshelter-rack-automatic-transfer-switch-1u-10a-230v-c14-in-12-c13-out-50-60hz/?parent-subcategory-id=88952&range=61810-rackmount-transfer-switches&selected-node-id=27602440314
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