Installing a 200 amp sub panel in your home provides additional circuits to power more appliances and equipment. Wiring a sub panel properly ensures safe, reliable power distribution. This guide covers everything you need to know to wire a 200 amp sub panel correctly.
Selecting the Right Sub Panel
The first step is choosing the right 200 amp sub panel for your needs. Here are key factors to consider:
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Number of spaces - Determine how many circuits you need to power now plus room to add more later. Common options are 8, 12, 16, 24, and 30 spaces.
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Indoor or outdoor - Indoor panels have a neutral bar while outdoor models have a solid neutral wire. Ensure your panel matches the location.
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Main breaker or main lugs - Main lugs allow connecting the feed wires. A main breaker provides overcurrent protection for the sub panel.
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Aluminum or copper bus bars - Copper bus bars are ideal for conductivity. Aluminum is cheaper but more prone to oxidation.
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Amperage rating - Match the main breaker amp rating to your supply wire amp capacity. For 200 amp supply, choose a 200 amp main breaker panel.
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Phase - Most homes have single phase power. Check that the sub panel matches your electrical system phase.
Selecting the optimal size sub panel with suitable specs prevents issues down the road.
Wiring the Sub Panel
With the right sub panel selected, you can move on to the wiring. Follow these key steps:
1. Turn Off Main Power
Shut off the main breaker in your main electrical panel. Verify power is off with a voltmeter before working.
2. Mount the Sub Panel
Mount the sub panel in the desired location securely. Leave at least 30 inches of space in front of it for access.
3. Run Conduit to the Sub Panel
Run rigid metal conduit or EMT conduit between the main and sub panel locations. Do not use flexible conduit or Romex cable.
4. Pull the Supply Wires
Pull the supply wires from the main panel through the conduit to the sub panel. Use THHN/THWN-2 insulated copper wire. Size according to the sub panel amperage - 200 amps requires 2/0 AWG wire.
5. Connect the Grounding Electrode Conductor
Connect a 6 AWG grounding electrode conductor from the sub panel ground bar to a grounding rod or other electrode.
6. Connect the Neutral and Ground Bars
Connect a 6 AWG bonding jumper between the neutral and ground bars in the sub panel. Keep them isolated in the main panel.
7. Attach the Supply Wires
Connect the supply ground wire to the ground bar in the sub panel. The neutral wire goes to the neutral bar, while the hot wires go to the main breaker or lugs.
8. Add Breakers and Connect Circuits
Install breakers for each new circuit. Connect the circuit wires to the appropriate breakers using 12 or 14 AWG THHN wire based on the amperage rating.
With the sub panel wired properly, restore main power and test operation of all circuits. The sub panel should now offer expanded capability to power additional appliances and equipment. Contact a qualified electrician if you have any doubts working with 200 amp electrical systems.
Sub Panel Grounding and Bonding
Proper grounding and bonding is critical for safety. Here are key grounding tips:
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The grounding electrode system wires must be connected to the sub panel ground bar. This ties the system back to the main panel ground.
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The ground and neutral bars must be bonded together with a 6 AWG jumper in the sub panel only. Never bond them in the main panel.
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Use 10 AWG wire for equipment grounding conductors that connect receptacles and devices to the ground bar.
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Ensure the ground and neutral wires are separated in all branch circuits. Ground wires connect to the ground bar while neutral wires connect to the neutral bar.
Maintaining separation of ground and neutral throughout the circuits avoids problems from stray current.
Common Sub Panel Mistakes
It's easy to make wiring errors that can create hazards when installing a sub panel. Watch out for these common mistakes:
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Undersized supply wires - Wire ampacity ratings must match the main breaker amperage to avoid overload. Do not use undersized wires.
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Loose connections - Ensure all wire connections are tight and secure to prevent arcing faults and hot spots.
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Unsecured wires - Use cable ties and wire anchors to keep circuit wires secured neatly inside the sub panel.
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Wrong breaker types - Avoid mixing breaker brands and types in the sub panel. Use properly rated breakers.
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No separate ground bar - Always connect grounds to a ground bar, not the neutral bar in a sub panel.
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No ground rod - The sub panel must have its own grounding electrode conductor connected to a ground rod or other electrode.
Paying close attention to sub panel wiring best practices avoids these mistakes during the installation process.
Recommended Safety Tips
Working with 200 amp electrical systems requires great care and caution. Follow these tips to stay safe:
- Turn off all power and verify it is off before starting work.
- Wear insulated gloves and other protective gear when wiring.
- Carefully inspect all connections before restoring power.
- Do not work alone - have someone ready to switch power off if needed.
- Call a professional electrician if you have any doubts or concerns.
Rushing the job or taking shortcuts risks electrocution or fires. Following safety protocols is crucial when wiring a 200 amp sub panel in a home.
Wiring a 200 amp sub panel takes careful planning and methodical installation. Understanding sub panel design, grounding techniques, safety protocols, and avoiding common mistakes helps ensure the sub panel meets code and provides safe, reliable expanded electrical capacity in the home.