The inspector can also advise what amperage your subpanel should be. Typical panels in the US have 100 or 200 amps, but older homes, or homes in other locations may only be able to support a 60-amp panel. An inspection and permit for your subpanel will ensure that you don’t have any insurance or liability issues.
Avoid purchasing used panels or cables or you could damage your electrical system and potentially cause a fire. You can find subpanels and attachments at hardware stores. You’ll need a subpanel, 4-wire feeder cable, feeder breaker, and connectors to complete the job.
Place the subpanel about 1 foot (0. 30 m) away from your main panel.
A newly furnished shed could use an additional subpanel inside of it so the main system isn’t overloaded. If you build an additional room as an add-on to your home, you may need a subpanel in it so your system can power it.
You also needs to be able to access the subpanel easily and maneuvering inside a small closet may be difficult.
Use a flashlight or portable lamp so you can see while you’re working. Make sure that the system is turned off and there is no power running through the breakers by testing the lights in the room.
Check the electrical outlets on the wall if there are any. Most electrical outlet boxes are mounted on the side of a stud, so they can help tell you where one is located.
Mark where the screws need to be drilled into the wall with a pencil or marker. Place the panel at a height of about 5 feet (1. 5 m) so you can easily access it but children or pets cannot reach it. Check local building codes to see if you have to mount a subpanel at a specific height.
Give the panel a gentle shake to make sure it isn’t loose and won’t fall off of the wall.
Use a pair of pliers to remove the knockout slug if you’re having trouble taking it out.
The screws do not need to be installed in a wall stud. Screw on the retaining nut to the bottom of the connector inside of the subpanel.
You may need to remove a knockout slug to insert the wires into the main panel. There should be a black wire, red wire, white wire, and bare metal wire. If you’re installing a subpanel in a separate room from the main panel, use a longer feeder cable to reach it.
A bus bar is a metal strip or bar used to connect wires to power the panels. Check the inside of the door of the main and subpanel for a diagram showing the location of the bus bars and neutral bars. If the end of the wire is covered by sheathing, use a wire stripper or a utility knife to remove about 1 inch (2. 5 cm) of the sheathing to fit the exposed wire into the bus bar. Use a longer cable to reach a subpanel installed in a separate room.
Use a wire stripper or a utility knife to remove the sheathing at the end of the wire so the exposed wire can be inserted into the breaker. You may need to loosen the screws on the feeder breaker first to insert the wires. If you’re adding a subpanel in a room away from the main panel, make sure the cable is long enough to reach from the subpanel to the main panel.
Don’t try to force or jam the feeder breaker or you could damage it. You can put the feeder breaker into any empty slot in your main panel.
Give the wires a gentle tug to make sure they’re fastened securely.
If the subpanel isn’t working or you’re concerned it wasn’t installed correctly, call a licensed electrician to come inspect the subpanel.
