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How To Install Sub Panel Wiring?

What Is The Main Panel?

The NEC defines the Main Panel as a cabinet that has protective and controlling devices like circuit breakers, switches, and fuses. NEC stands for National Electric Code. It can protect from power cuts and controls light and heat. The main panel has different names like distribution board, panelboards, load center, and breaker box.

It must be installed in solid structures or walls and must be accessible from the front. For residential purposes, it has three wires that can provide a single-phase voltage supply of 120V and 240V. It comes with 2 hot wires that are connected to the main breaker and two poles. There is also a neutral wire which is for the panel box’s neutral terminal. For the earthing system, there is a ground wire.

When there is an electric surge, the main panel acts as the first line of defence. It works by protecting electrical appliances and can prevent hazardous fire as well as electric shocks.

What Is The Subpanel?

A subpanel is also called a Remote Panel. It works just like the main panel and can offer protection against electric faults, surges, and shocks. With a subpanel, there will be a secure distribution of electric power from the main panel. It has two poles circuit breakers that can provide power to specific applications. In a subpanel, there are two poles at the main panel and features 2 hot wires along with a neutral wire (N) and ground wire (G).

A subpanel can provide additional circuit spaces so that there will be a smooth operation. By using electric power control to the circuits, it offers maximum protection and safety. Furthermore, it can also provide a secure electric distribution system. Different manufacturers have come up with various types of main and sub-panels. This enables a user to choose for both indoor and outdoor applications.

1. Installation of 60 Amp Subpanel for 120 & 240 volt

The wiring installation of a 60A subpanel is according to the system requirement. Some can also go for 50A, 100A, and 150A. It has two poles breaker to the main panel. The output wire has two hot busbars of black and red colors. These wires are joined to the two poles breaker.

Additionally, it also comes with neutral and ground wires that enter the subpanel for connecting the neutral terminal and ground terminal. It can supply 120V and 240V branch circuits with single or two poles. However, neutral is only required if there are GFCI outlets of circuit breakers.

Do note that the main breaker lugs are hot even when the switch is turned off. It features a safety switch or energy meter that lets you pull it to turn it off. It is not authorized to use a 30A breaker for switches and outlets of 20A.

You must always use a double pole breaker for a single appliance. Similarly, two single pole breakers cannot be used for appliances of 240V. It must be accompanied by a power button so that there will be secure performance.

2. Installation of 150 Amp Subpanel for 240 volt

The wiring installation of a 150A subpanel for 240V has three wires. These wires enter the main panel through the two poles breaker. It has two hot wires (L1 and L2) and a ground wire.

Keep in mind that there is no neutral wire as it only runs on 240V circuits. In case you need to run single phase 120V circuits, there will be a need for a neutral wire. You can do it from the main service panel.

Always note that you must never use two GFCI and AFCI on the same circuit. This can lead to unwanted tripping operations.

3. Installation of 100 Amp Subpanel for 120 volt

Installing 100A subpanel for only 120V there is a need for three wires. Hot 1 or Line 1 from the pole breaker, ground from the ground terminal, and neutral from the neutral busbar.

For having a supply voltage of 120V, you need to connect the Hot 1 to both hot lugs through the jumper wire. Keep in mind that you can even use lower ratings like 30A, 40A, 50A, and 60A.

4. Wiring Color Codes

You must always follow the NEC wiring color codes for general practice. The following are the NEC + general wiring color codes.

  • Hot 1 or Line 1 = Black
  • Hot 2 or Line 2 = Red
  • Protective Ground Wire (Bare Conductor) = Green/Green with Yellow Stripe
  • Neutral Wire = White

If the white wire has voltage, you must cover it with black tape or strip. This helps to identify it as a Hotwire. You must never use green for wires that have voltage. Avoid aluminum wires and use copper wires for reducing heat and resistance while wiring the main panel box.

5. Tools and Materials

Some of the tools that you will be requiring for installation are –

  • Cable sheathing stripper
  • Flathead screwdriver
  • Hammer
  • Handy boxes (for outlets, switches, etc.)
  • Head screwdriver
  • Non-metallic cable (for 15-amp and 20-amp circuits)
  • Utility knife
  • Wire clamps (for feeder cable knockouts)
  • Wire stripper

Safety Precautions

You must always take safety precautions before you go for subpanel wiring.

  • Use the right size of cables and wires. It is important to have the appropriate size of switch and outlets as well circuit breakers. Using a wire and cable size calculator will help to find out the right size of the gauge.
  • Always disconnect the main power supply before you go for installation, repair, or servicing. You must turn off the main switch on the distribution board.
  • Read the instructions and cautions carefully. You will have to follow them strictly so that there will be no hazards.
  • While installing or repairing, you must never touch metal parts when your hands are wet. Also, you must never stand wet.
  • You must possess knowledge about electricity as playing with it can be dangerous and fatal. Always perform repairing and installation under the guidance of professionals who are experts in dealing with electricity.
  • The distribution board must be protected from water areas and corrosion. For this reason, you must never install it 7 feet above the floor. Additionally, the wires must be covered and not stay
  • It will be dangerous and illegal to perform electrical work. You must always seek the help of a licensed electrician when you are looking to change the electrical wiring connections.


Whether it is about identifying panel circuits or connected loads, you must have some knowledge about electricity. Subpanel wiring is an important task. However, always do it in front of a licensed electrician. You must possess thorough knowledge about the grounding and neutrals of the panel. There are many other factors like the length of the distance to the panel, calculating the wire size, and appropriate usage. If you don’t accurately wire the sub-panel, it can lead to hazards.

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