Image by Pok Rie via PexelsHomeowners install sub-panels one of two people to expand the obtainable circuit room of their main panel or to affix a distant part of their property to the main panel. Everything the reason, it’s essential that the installer appropriately connects the sub-panel via a double-pole breaker. Safety need to be the primary concern when functioning on something with power within the home. That is encourage to always get a experienced to do any work through electricity.

You are watching: Wire gauge for 100 amp subpanel

Typically, you require to connect a 100-amp sub-panel to the main panel via a correctly-sized breaker the 100 amps. You deserve to still use a 100-amp sub-panel ~ above a lower-amp breaker, however you will not be able to utilize the full 100-amp capacity of the panel. Installation a 100-amp sub-panel ~ above a 200-amp breaker would allow the wires to overheat.In this article, we will study the offers of sub-panels and breakers in transferring power roughly the home. We will additionally look in ~ the correct way to install the sub-panel while ensuring that security is always the an initial consideration.If you want to uncover the best breakers, click here.

Sub-Panels and Their Uses

Your electric firm supplies power to your home via the electric meter to your main service panel. This circuit breaker dashboard protects her wiring, and also the breaker architecture trips if over there is an overload.Should the capacity of this main panel be insufficient for the needs of the home, many homeowners climate install a sub-panel. An electrical sub-panel feeds off the key panel and also is a mini variation of that main panel. Electricians refer to these together a company panel or circuit breaker sub-panel. People install sub-panels for a variety of reasons, such as separating electric areas, creating space for circuits, and running new cables for a remodel.

Separating electrical Areas

You may want to separate the electrical functions in one area that your building from another. For example, if there is a separate dwelling ~ above the building or one office, it have the right to be useful to have separate circuits. 

Creating much more Space for Circuits

If the main panel has actually run out of spaces to install new circuit breakers, climate you might need to download a sub-panel to enable for additional circuits.


When remodeling an area of your home, it deserve to be valuable to run brand-new cables to a sub-panel close to the brand-new space. It can be difficult to reroute many wires, and this have the right to be a solution because you only have to route one key cable needs to the key panel.Image by Milivoj Kuhar via Unsplash

Sub-Panel Capacity 

When adding a sub-panel, the is essential to consider how much capacity friend require and how lot the main panel deserve to spare. If your main panel go not have actually extra capacity, climate you could need to consider upgrading it before installing a sub-panel. For example, when adding a 100-amp sub-panel to power a shed or garage, you should ideally have a 200-amp key panel for this reason that adding the extra power demand does not threat overloading the system. In theory, you can add a 100-amp sub-panel to a 100-amp main panel, yet the key panel would need to have a far-reaching unused volume to permit this.Also, the sub-panel should be correctly-sized because that its needs. Girlfriend will need to consider the extra load that you call for to decision what size sub-panel to install. The a good idea to add a tiny amount of spare capacity for any future needs.

Electrical Circuits

Each breaker on the main panel or a sub-panel connects a circuit of strength somewhere in your home. This are typically 120-volt circuits (15-20 amps) that operation most family members items. In bedrooms and also living rooms, there are usually 15-amp circuits that affix lighting and also outlets in a specific area. 20-amp circuits generally supply areas like kitchens or garages where there are larger appliances. Some large appliances, such as air conditioners or variety ovens, may also have a specialized circuit as result of the quantity of power they have to pull. This is generally the instance if lock require much more than fifty percent the circuit’s capacity. This circuits are normally 240-volt circuits that can pull 20 to 60 amps.On the main panel, there would be a breaker particularly linking the sub-panel come the key supply. The sub-panel would, therefore, regulate a branch circuit from the key panel. This branch circuit would then get separated into multiple smaller circuits fed from the sub-panel.Image by Image4you via Pixabay


A breaker is a move that deserve to be manually shut turn off or immediately tripped as soon as there is a failure in the system. This is a safety attribute that allows the mechanism to safeguard itself from electrical fires. The breaker’s rating in amps shows the maximum quantity of power of the circuit should provide.A breaker consists of a resolved contact and also a moving contact called electrodes. This contacts room closed when a breaker is to work normally. If over there is a fault, the contact will instantly open, and you can likewise open lock manually.When the contacts room separated, one arc is struck in between them, and this is well-known as the arc phenomenon. The current will proceed to flow until this arc discharges, and the circuit is thus interrupted. A circuit breaker, therefore, seeks to disrupt this arc as rapid as possible.On the key panel, there will be circuit breakers because that each circuit. If over there is a sub-panel, climate there will be a large breaker that connects to it. This breaker would certainly supply the feeder circuit the powers the sub-panel and would be a double-pole breaker through double-size levers.

Single-Pole and Double-Pole Breakers

Electricians frequently use single-pole breakers for the smaller sized 15- to 20-amp circuits. These consist that one hot wire and one neutral wire. The usage of double-pole breakers is for larger circuits and also consists of two warm wires linked by a neutral wire.Single-pole breakers have narrow switches ~ above the panel and tend to power appliances such as lighting, fans, computers, televisions, etc. If over there is a system fault or if the is overloaded, climate the single breaker will expedition to protect the circuit.Conversely, double-pole breakers have actually double-switches. They generally power huge appliances together as electrical ranges, waiting conditioners, electrical water heaters, or a sub-panel. If there is a quick circuit brought about by a fault or overloading on the circuit, then both switches will pilgrimage (source).

Connecting a Sub-Panel

Connecting a sub-panel have the right to be a systems for various electrical challenges. The size of the sub-panel will count on what it will power and also how much excess volume exists in the key panel. That connects to the main panel via a double-pole breaker and cannot exceed the amperage of the key panel.Importantly, the breaker feeding the sub-panel need to be properly sized. A 100-amp sub-panel deserve to be associated by a breaker as much as 100 amps, depending on its requirements. You might use a smaller breaker, but then that would certainly limit the fill that the sub-panel would be able to deliver.Generally, when installing a 100-amp sub-panel, it would be connected by a 100-amp breaker.What’s likewise important is utilizing the correct-size wires to feeding the sub-panel (source). Once installing a 100-amp sub-panel, friend will must use one of two people 4AWG (American wire Gauge) copper cable or 2 AWG aluminum, three-conductor cable. Aluminum cable is cheaper than copper cable and carries the hazard of corrosion. Three-conductor cable comprises four wires — two warm wires, a floor wire, and also a neutral. The dashboard itself need to be attached come a wall or other secure surface. If that is set up outside, climate it have to be one that has actually been approved for exterior use. That will need at the very least three-feet clearance on all sides and also be straightforward to with so you can accessibility switches. You cannot install the in a restroom or a closet.The sub-panel connects come the main panel via a circuit breaker in the main panel. This is known as a feeder breaker and is a 240-volt circuit breaker. Due to the fact that it is a double-pole breaker, it will certainly take up two nearby spaces on the key panel, therefore you need to have actually or create capacity for that.Connecting a sub-panel is ideal done by a default electrician. Countless local codes make it illegal to download your own sub-panel, and some don’t allow homeowners come do any of your own electrical work (source). Installing a sub-panel will involve the adhering to steps:Run the feeder cable from the key panel come the sub-panel.Connect the two hot wires come the sub-panel warm bus bars.Connect the neutral wire to sub-panel neutral bus bar.Connect the grounding wire come sub-panel ground connection bus bar.Attach the warm feeder wires to the feeder breaker at the main panel.Connect the feeder neutral and also ground wires to the main panel. Connect the feeder breaker right into the main panel. Once connected, a sub-panel can then be set up with individual circuit breakers because that the circuits that is being mounted to service. Ultimately, the connections must all be covert by a cover, and also a homeowner need to only accessibility the breakers.

Consult an Electrician

An post such together this can not cover all eventualities and codes that use in every countries and all local municipalities.For this reason, as well as for the safety and security of you, her family, and your home, that is ideal to consult with a neighborhood electrician prior to any type of electrical work.When electrical power is concerned, a tiny bit the knowledge can be deadly, and it is not worth acquisition the risk simply to conserve a little money.

See more: Feeling Nostalgic, Houston? This Is What Time Does Greenspoint Mall Open

Final Thoughts

Any form of electrical work need to never be taken into consideration a DIY project with little an easy knowledge of electric work. Sub-panels offer good convenience come the homeowner. Lock can administer proximity to circuit breakers, and also they deserve to reduce the quantity of wiring forced to add a new area come your power source. They also enable homeowners to upgrade or increase their power demands for a relatively low cost. You must have actually them correctly and safely installed, adhering to all the compelled guidelines and codes. Where possible, sub-panels need to be set up by a default electrician so that breakers and wiring are correctly sized, and also the surroundings is as safe as feasible to prevent any kind of avoidable electrical faults.