I’ve recently become the owner of a home that was constructed in the mid 1950s (in the US). As such, not all the outlets are grounded, three-prong receptacles, since that wasn’t code-required at the time. It looks like a few have been added or upgraded over the years, but there are still many that are ungrounded. What is the best way to go about converting those receptacles to be grounded? Will that require a professional? It seems like probably the kind of electrical work that I am capable of doing myself, but I am also very much not an electrician.