Tacklife Outlet Tester | $5 | Amazon | Promo code QBK2WKE9
Photo: Amazon

Before you do any electrical work around the house, you might want to pick up this outlet tester for $5 with code QBK2WKE9. A series of three lights corresponds to a chart printed right on the device, telling you if the outlet is properly grounded, has reversed polarity, and more. It’s not fancy, but it’s cheap, and could save you from a nasty surprise.