Below, is version 2 of a simple power distribution scheme that I developed in my last brewery after I had 4-wire NEMA 14-30 service installed in my garage.
In version 1, I used 12/4 SJOOW power cord, which limited me to a total of 20A of combined 120/240 service. This time I used 10/4 SJOOW power cord and wired the inside pigtails from the receptacles using solid wire I stripped out of 10/3 Romex. First off, It is clear to me that doing this kind of thing with 10-guage wire is fairly uncommon. The difference in difficulty of build between 10-gauge and 12-gauge wire feels like an order of magnitude. Ten-gauge is both large in diameter and very stiff. Wire nuts are not designed for working with 30A wire. Even the large red wire nuts are too small. I tried using the blue Ideal in-sure push-in wire connectors. They are very nice, but I was unable to insert SJOOW power cord 10-gauge stranded wire into these cool little devices. I was about to give up and fall back to using 12-gauge wire when I found something even cooler than the Ideal in-sure connector. They are made by a company called Wago. The part number for the connectors I used is 221-613 (
https://www.amazon.com/gp/product/B085ZQKQD2/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1). These lever nuts are not cheap, but they are the only game in town when joining 10 gauge solid and stranded wire.
Anyway, the combination receptacle that I employed in the design is usually used to provide a light switch and a receptacle in one duplex package. However, if one breaks the tab that joins the hot input terminals on the toggle switch and receptacle, connects the hot (black) wire to the hot input terminal of the toggle switch and then connects the hot output terminal of the toggle switch to the hot input terminal of the receptacle, it gives one a toggle switch controlled receptacle that can be used to turn a pump on and off. The other side of the distribution box is a NEMA 6-20R receptacle that can power 20 amp 240 devices.