A magnetic plug and method of plugging unwanted knockout holes in electrical containment enclosures. The method requires only one hand and is performed without tools. Everything can be done from outside the electrical containment enclosure. The actual plugging step is completed in a few seconds. One of nine invented plugs is selected to best match the nine standardized hole diameters found in electrical containment enclosures. Selecting the correct plug size results in the best fit and feel since perception matters. Savings in time and money is expected to pay back the cost of a plug.