Cord Craftsmanship: How To Make Your Own Heavy-Duty Extension Cord

As a DIYer, there is a lot you can do to upgrade your skills and build up your toolkit. You can build an extension cord from scratch with readily available materials and resources. A heavy duty extension cord, mainly a generator cord, can be assembled from scrap wires and other resources for under $50. The time to make a functional and efficient generator cord depends primarily on your skills and commitment.

Many high-voltage DIY extension cord options comprise heavy-duty rubber cables, 20-amp male and female connectors, and wires. To build such an extension, you require a crimper for electrical wire, a star screwdriver, a utility knife, and a flathead screwdriver. Follow these steps to create a high-wattage rubber extension cord from scratch.

1. Material Collection

You require suitable materials and resources to build a 20 amp extension cord for household and commercial use. First, collect a double gang PVC conduit box, a 120-volt receptacle, and a single pole switch. Get a 130 volt, 15A extension cord male plug, about seven fit 14/4 SOOW cables, and 20-gauge crimp-on ferrules. You need ½ inch threaded bushing, ½ inch threaded nylon dome connector, and a combination switch wall plate.

Items like the ferrules and nylon dome connector are hard to find. However, many trusted online stores offer these on various wattages and designs. Check out the catalog to find suitable units for your work.

2. Prepare the Wire

Wire preparation is the first step on how to make an extension cord. Identify the ends of the wires and cord connectors with matching color orientations. Connect each connector to a matching cord end. Always remember to correspond the black wire with gold screws, the white wire with silver screws, and the green with green screws.

Use a utility knife to split and remove the protective rubber sheath. Be sure to remove the correct amount of rubber. Ensure no individual wires remain on the connector's outer sheath. Remove the rubber to leave about half of the bare copper wire. It should be long enough to reach under your connector screws. Twist your copper wires to fit appropriately into the holes beneath the colored screws.

3. Fit the Wire into the Thread Box

Mostly, the device box of your 20 amp extension cord will have an inch hole in its bottom. Fit the first bushing with the PVC conduit glue into this hole. You will remain with around ¾ inch of hole space. Install the second bushing and fasten it with PVC conduit glue. That reduces the hole space to about half an inch.

Lastly, fit the nylon dome connector into the remaining hole space. The nylon dome connector mostly has a male thread for screwing into the second bushing. Use the rubber o-ring sold together with the nylon dome connector.

After fitting in the nylon dome connector, feed in enough SOOW cable. Tighten the nut on your dome connector to clamp tightly on the cable. That relieves strain on the power cable and ensures anything that tugs on the cable does not interfere with electrical connections.

4. Connect the Receptacle and Switch

The next step in building an extension cord with the switch is to wire the switch and receptacle. Crimp your 30-gauge ferrule onto all the wires flowing into the box. The terminals of the receptacle and switch work only with solid wires. The role of the ferrules is to change the stranded wire into a solid one on its terminals.

Users who do not have access to ferrules can utilize GFCI-protected, outdoor-rated receptacles. GFCI receptacles have terminals that support stranded wires. Fix the incoming neutral and ground wires into the silver and green screws on your receptacle. Fit the hot wire into the switch. Using a jumper wire, connect the hot wire to the brass screw.

Switches and receptacles have square vinyl fitted on the mounting screws. You should remove the square vinyl before you connect the devices to the PVC box. That helps facilitate carrying the ground from the receptacle to the switch.

5. Test Your Extension Cord and Enjoy

You have built a high-quality flat extension cord. It is time to test if it works and can power your devices and machines. Plug your extension cord into a power outlet and switch it on. Plugging it into a device or appliance lets you know if it works. Wait for some time to see if the extensions get too hot. If it does, you must change your wire choices.

Wrapping Up

Building a heavy-duty extension cord from scratch takes time and money. Start by collecting the necessary materials and tools. Follow each step to avoid incorrect fitting wires, switches, ferrules, and other extension cord components. Everything must be perfect in order to prevent the potential of fire outbreaks. Do not plug in devices that require more power than the extension cord can handle.