By Safety Precautions
Safety is key when running a subpanel in a detached building. Prioritize proper grounding of the subpanel for installation. This aids with protection against electric surges, fire and shocks.
Comprehend why proper grounding is paramount and the diverse methods to do this.
Put on safety gear
Safety must come first for any electric work. To install a subpanel in a detached building, you need to prepare. Wear safety gear, like rubber-soled, non-conductive shoes, gloves and glasses that are impact resistant. Put on a long sleeve shirt and pants made of cotton or other non-synthetic material. This offers further protection from sparks or shocks.
Also, keep tools and materials away from the work area. Especially flammable items, so you don’t need to worry about them being dangerous. In the case of a fire or an electric shock.
Gather necessary tools
Before grounding a subpanel in a detached building, have all necessary tools and materials. Size of job impacts needed tools. Examples are:
- Shovel,
- Shovel extensions,
- Soil testing equipment,
- Copper grounding rods,
- Connectors,
- Metal pipe fitting,
- Ladder.
Also, an electrical tester is needed to check wiring before handling. Protective gear, such as safety glasses and leather gloves is also needed. Dispose of any excess material or electrical wire when finished. Proper disposal keeps everyone safe!
Shut Off Main Power
Before starting any electrical project, switch off the main power at the subpanel. This safeguards you and anyone else working on the project from electric shock. Plus, no power will flow through the wires while you work.
So, let us check how to turn off the main power:
Locate the main breaker box
Before starting, switch off the main power at the breaker box. Locate the meter or breaker box close to the metallic case of the power line. Note that all house electric lines should have a protective shield for safety. This is especially essential when working with an external, detached building lacking these protective measures.
Confirm there is no current running through the main breaker or meter, by using a voltage tester. This box should be located as it is where the subpanel ground wire and bonding clamp will be connected. Depending on the age or newness of the building system, you may need to buy extra materials such as appropriate electrical boxes and conduit. Check with the local building codes or an electrician if necessary.
Shut off the main breaker
Safety comes first when you are making electrical improvements or repairs at home. To ensure safety, turn off the main power switch located in your service panel. Flip all breaker switches to “Off” and disconnect electrical supplies from appliances and other equipment.
Test for residual current in any open circuits. Be sure all supply lines are disconnected. Keep non-electrical personnel away from working areas during repair jobs. If you sense a current, call an electrician for help.
Connect the Ground Wire
Connecting a ground wire to a subpanel in a detached building is possible. But, local codes must be followed!
- Switch off all power and label all wires.
- Locate the nearby ground rods.
- Attach the ground wire.
- Use the ground rods to connect the ground wire to the subpanel.
- Done!
Connect the ground wire to the subpanel
Before any wiring is done, the ground wire must be connected to the subpanel. This is an important safety step.
- Firstly, turn off the power at the main breaker panel. This will stop any electricity from flowing through the wires.
- Next, find the grounding bar in the subpanel. Use a screwdriver to loosen it so a bare copper grounding wire can be slipped in. Cut or strip about half an inch from one end of the wire. This will leave two exposed copper leads that can attach to the grounding bar.
- Run about a foot of extra wiring beyond this connection point. Tie off all ends with electrical tape or cable ties.
- Connect one end of the wire to the grounding bar. Secure it with a screwdriver. Connect the other end of the wire outside your house. Use an appropriate connector, such as an eye bolt with upraised threads. Attach it securely into drywall or wood.
- Check all connections for tightness. Then, turn on the power at the main panel. All done!
Connect the ground wire to the grounding rod
To properly ground a detached building’s subpanel, do the following:
- Run a copper ground wire from the subpanel’s grounding bar to an 8’ copper-clad or galvanized steel grounding rod near the panel. Use an approved U-bolt clamp for attaching. No nails or screws.
- After attaching one end of the wire to the rod, attach the other end to a ground lug on the subpanel. Make sure all connections are tight and secure.
- Inspect the wiring.
- Turn power on after everything is done.
Now the specially grounded detached building is ready!
Connect the Neutral Wire
To ground a subpanel in a detached building, the neutral wire must be connected correctly. Ground and neutral wires must be attached to the subpanel. Doing this ensures a reliable ground connection, preventing shocks, fires and other hazards.
This article explains how to correctly connect the neutral wire in a detached building:
Connect the neutral wire to the subpanel
When connecting the neutral wire to the subpanel of a detached building, it’s important to follow proper steps.
- Find and identify the white neutral wire. This wire is usually marked with colored tape and must be connected to the buss bar in the subpanel.
- Make sure all other wires are secured with screws and washers, and that there’s no exposed wire.
- Attach a bonding cable (green insulated copper) from the ground lug on the panel box to a metal structure nearby, such as a cold water pipe or I-beam. This provides an alternate path for electricity flow in case of a fault. Make sure the bonding cable is properly attached with clamps and connectors.
- Attach ground rods if necessary and connect them to the grounding conductor termination point of the subpanel.
- Turn on the electricity at the main service panel. Check to make sure everything works before leaving the project area.
Connect the neutral wire to the main breaker box
To protect yourself, property, and the electrical system, it’s essential to understand all instructions before attempting any wiring.
To connect the neutral wire to the main breaker box, switch off the main breaker near the detached building. Then, attach one end of a 12-gauge cable to the double-pole 30-amp breaker in the main panel. Ensure not to mix up the cable ends. Connect a short section of cable with the same gauge size between these two breakers. This will provide grounding for your home or business.
Take another 12 gauge cable. Attach one end to a ground screw at the subpanel. Run this through an approved conduit into your detached building. Fasten it securely at both ends of your conduit setup. This is important for safe installation and to prevent shock or short circuit risks.
Finally, attach two ends of the 12 gauge cable to the poles on both sides of the subpanel’s 30 amp double-pole breaker. Now the neutrals wire is connected correctly and no wire will carry more current than its capability!
Connect the Hot Wires
Grounding a subpanel in a detached building? Important! Connect the hot wires between main panel and subpanel. A ground wire must be run from the main panel to the subpanel. Make the connection with the ground bar – this is important to do correctly. Keep wiring safe and secure.
Let’s look into more detail. How?
Connect the hot wires to the subpanel
Identify each voltage’s circuits before connecting hot wires to the subpanel. Depending on the building size, you may have more than one voltage. Make sure to double-check after connecting.
- Check if the subpanel has breakers for each circuit.
- Match the hot wire to its breaker.
- Remove an appropriate knockout from the plate, insert the wire, and secure a strain-relief fitting.
- Connect the wire to the breaker lugs or terminals from the back of the panel.
Verify that all hot wires are connected to the brokered circuits. Replace any unused knockouts with blank plates or plugs. Put a cover on the subpanel using the installation hardware kit screws or fasteners.
Connect the hot wires to the main breaker box
Choose one of the hot wires to be the neutral connection and attach it to the neutral bar in each box. Connect a hot wire from each subpanel’s breaker to the main breaker box’s bus bars. Finally, use a grounding wire to make the loop from each breaker to ground – either directly or with a grounding rod in the earth. Secure all connections. Depending on local building codes, inspections may be necessary.
Ensure that all inspections are done before using the equipment.
Test the Subpanel
Before installing a subpanel in a detached building, it’s essential to test the wiring and connections. This will guarantee all connections are correctly grounded and safe.
In this section, we’ll look at the procedure and tools you need to test the subpanel:
Turn on the main breaker
Before grounding a subpanel in a detached building, turn on the main breaker to have power. Be careful when working with electrical circuits and follow safety protocols.
To turn it on, locate the main breaker and switch it ON. Usually, the switch will be down for OFF and up for ON.
Find the circuit board and check that all breakers are OFF, including any non-electrical appliances connected. With all breakers OFF, you can work on the subpanel without fear of electrocution or electric shock.
Test the subpanel for proper operation
Before you wrap up, check that the recently installed subpanel is functioning. Test this with a circuit tester to make sure power is running through each branch circuit and it works correctly.
Inspect the wiring connections in the subpanel. Look for signs of damage, dirt, pests, or anything else unusual. Ensure all wiring is tight and secure.
- Check the switches are set properly and secure with a screwdriver if necessary.
- Once secure, use the circuit tester one at a time in each outlet. A light should come on, showing there is current.
- If not, look over the wiring again. Fix any issues before connecting this panel to the main power.
Frequently Asked Questions
Q: What does it mean to ground a subpanel in a detached building?
A: Grounding a subpanel in a detached building is the process of connecting it to the earth to create a path of least resistance in case of electrical faults, ensuring safety for the building and its occupants.
Q: Can I use the same grounding rod for the main panel and subpanel in a detached building?
A: No, each panel must have its own grounding rod, which should be at least 8 feet long and connected to the ground wire using an acorn clamp.
Q: What size wire should be used to ground a subpanel in a detached building?
A: The size of the wire will depend on the amperage rating of the subpanel. Typically, it should be at least 8 gauge for 50-60 amps, 6 gauge for 70-100 amps, and 4 gauge for 100-amp panels.
Q: Can I use a metal conduit as the ground wire for a subpanel in a detached building?
A: No, a separate ground wire is required to be installed to ensure proper grounding of the subpanel. Metal conduit cannot be used as a substitute for a ground wire.
Q: Should I install a main disconnect switch for the subpanel in a detached building?
A: Yes, a main disconnect switch should be installed at the subpanel to allow for quick disconnection of power in case of emergencies or when maintenance or repairs are needed.
Q: Do I need a permit to install a subpanel in a detached building?
A: Depending on your location, you may need to obtain a permit from your local building department before installing a subpanel in a detached building. Check with your local authorities for their rules and regulations.
