What Size Wire Do I Need for a 100 Amp Service?

What Size Wire for a 100 Amp Service?

100 amp wires

A #2 AWG wire is needed for a 100 amp service. This wire is used when the run between the breaker panel and the electrical load (such as an air conditioner) is long, like in large commercial buildings. A #4 AWG wire will be needed if the distance between the breaker panel and the electrical load is less than 50 feet. A 6AWG wire will be needed if the distance between the breaker panel and the electrical load is less than 20 feet. Remember that these are just guidelines, not firm rules.

These services are relatively rare in homes, where 30-50 amp services are more common.

Where Can You Use a 100 Amp Service?

A 100 amp service can be used in commercial applications like large office buildings with many air conditioners or server rooms with lots of computers running at once. It is also used when there are many heating appliances (such as in Fire Stations). Even though it can sometimes support smaller residential locations like houses, it usually isn't used because people don't like paying for an upgraded service they don't need.

What Wire Type Should I Use For A 100 Amp Service?

The wire type needed for a 100 amp service will depend on the application you will be using it for. If you are using the 100 amp service in commercial applications, you will need either stranded steel armored cable or IMC (Intermediate Metal Cable). If you are however using 100 amps in places like houses and strip malls, you will need to use either THWN (Thermoplastic High Heat Wiring Nylon) or UF (Underground Feeder).

When using this type of wire in commercial applications such as warehouses, you should make sure that the insulation is flame retardant. This will help prevent fires from occurring if something were to go wrong. Another thing to take into consideration when using this type of wire is the weight load it can support. Most 100 amp services that are put in at commercial locations, have a maximum weight load of 70 lbs per square foot.

Where Can I Use a 100 Amp Service?

A 100 amp service can be used in commercial and industrial locations like large office buildings with many air conditioners and server rooms with lots of computers running at once. It is also used when there are many heating appliances (like in Fire Stations). However, it is mostly only used in these types of areas because people don't like paying for an upgraded service they don't need.

Ground wire size for 100 amp service

The minimum size for a 100 amp ground wire is #8 copper or #6 aluminum.

Factors to consider when running 100 amps

There are many different factors you have to consider when you are running a 100 amp service in your home. These factors are circuit separation, wire size, voltage requirements, Uneven Distribution of Current on a Circuit, voltage drop, Current vs Resistance, and wiring type.

  • Circuit Separation
  • When you are determining how far apart to separate circuits (the distance between the furthest appliance on your power line), you should use the next voltage drop to determine where you need to separate them. For example, 6 volts would be 6 feet; 10 volts would be 10 feet; etc. When running a 100 amp service, this can get very difficult because there is no current listed for it. Also, many of the appliances that require more than 50 amps may start tripping breakers or fuses if they do not have enough space between them. Another factor to consider spacing out circuits is that thinner wires get hotter than thicker wires. Thicker wires will support more power and not overheat which creates a safe service for your home.

  • Type of Wire [to be organized]
  • The best wire size for 100 amp service is #4 aluminum wire with two 4/0 copper conductors which has a maximum continuous current rating of 183 amps and costs $1.02 per foot at the time of this article (12-9-2013).

    As we stated earlier, it would be difficult to fit circuits on your property if you were running a 100 amp service. The voltage drop between appliances would also need to be considered when placing them in the best places possible. In most cases, appliance manuals list the minimum space requirements needed to operate the appliance properly. Every building has a number of electrical appliances which all need to be run from the same service. So, it is important to correctly size your supply system so that you have enough capacity for the coming decades.

    An electrician will consider the expected load on each circuit when sizing your household's service. The maximum load for large wire is determined by the National Electric Code (NEC) and is usually based on 100% of the conductors' rating. Using this method, one 120V 15A circuit would draw 1440 watts.

  • Voltage Drop
  • Voltage drop has to be taken into consideration when choosing the correct wire for a 100 amp service. When you add up the voltage drop of each circuit, it should not exceed 5%. Voltage drop is the decrease in potential (voltage) between where the load draw power and where it connects to the source.

  • Current vs Resistance
  • When electricians size wires they use current instead of resistance because it's easier to find problems once there is an overload than just after installation if something isn't right. The National Electric Code dictates that Type THW and Type TW wire need to be sized at 20A, while AWG#10 wire must be 30A on circuits with loads under 80 amps. This means you need to ensure your total load does not exceed 20 or 30 amps on each 100 amp circuit.

  • Uneven Distribution of Current on a Circuit
  • If you have current spikes (high currents in only one wire) it can cause voltage drop and/or an increase in temperature which can cause fires or at the very least, bad connections that will short out after some time or starting arcing between two wires that are supposed to be separated by insulation barriers. This is something we want to avoid by using more than just enough amperage to satisfy our 100 amp circuit load requirement.(Which for this article we'll use 20A as our example.)

    You know your lights and stuff don't all draw the same amount of power so if you try and put too much on one switch it could get really hot and you might even start a fire. Sometimes it can even make big sparks in the switch, wear out quickly, or short! That's why you have more than one wire in the wall when you are installing your house. This is something we want to avoid by using more than just enough amperage to satisfy our 100 amp circuit load requirement.

  • Voltage Requirements
  • The voltage required for your service is not affected by the number of circuits or total ampacity. Even though you will be getting a 100 amp service, your household voltage will stay at 120 volts as this does not affect the wire size. The NEC only requires that the neutral and hot conductors maintain a 10% voltage drop from source to load.

Here are some of the best 100 Amp Rv wires and circuit breakers you can buy today

  • 2 Gauge 2 AWG 20 Feet Black + 20 Feet Red

  • 2 awg wire on amazon

    This 2AWG wire is perfect for transferring power from a battery bank to a electrical equipment. It is ideal for marine, RV and automotive applications. Copper cable is fully annealed per ASTM standards. Complies with SAE J1127. Has a tough, solvent resistant EPDM insulation jacket and is rated to handle up to 600 volts at 105 degrees Celsius. This 2AWG wire is highly flexible, making it easy to route your wiring in engine compartments and other tight spots which may not be possible with larger gauge cables.

  • EWCS 2 AWG UL Approved Marine Grade Tinned Copper Wire

  • 2 awg 600v wire

    Made in the USA. This marine grade wire is tinned for corrosion protection and will always be highly recommended for salt water areas, marine environments and other corrosive applications. It exceeds SAE and ABYC standards and is rated to handle up to 600 Volts. This type of wire easily resists Abrasion, Acid, Alkali and Gasoline.

  • Q2100 100-Amp Double Pole Type QP Circuit Breaker

  • 100 amp circuit breaker

    The Siemens double pole, 100-amp Q2100 circuit breaker is used for overload and short-circuit protection of your electrical system. This black breaker is rated for 10,000 amperes and features a thermal-magnetic tripping mechanism. The Q2100 circuit breaker requires only 1/2 In. per pole for wire bending space and has a maximum load of 240 VAC. It works in Siemens PL and ES series load centers. The size of the Q2100 circuit breaker makes it easy to install and easy to use in Siemens enclosures or panels. It provides easy plug-in connections in Siemens enclosures and the time saving Insta Wire feature enables the user to connect wires without turning off the main power (120V/240V). Circuit breakers should only be replaced with new tested and Safety Agency Listed circuit breakers, never use recycled breakers.

The Difference between 110V and 240V

Your 100 amp panel can be wired to supply either 110 or 240 volts, but cannot supply both simultaneously. You should select which one you want before you purchase the panel. If you choose to buy a new panel for 240 volts, it would require installation by an electrician so it would be best to switch over once installed to avoid future need for costly rewiring work.

The main thing to look for when deciding between these two voltages is the load.

If the majority of appliances will be small and draw less than 10 amps, you may choose to keep it at 110 volts. If larger or more expensive appliances like stoves and dryers are in use, 240 volt operation is preferred. This will allow higher power output and faster heating and drying times of certain appliances.

Aluminum Wire

Aluminum wire is the common choice for electrical service entrance wiring. It is rated at 100 amps and can carry anywhere between 90-110 Amps of continuously loaded current.

Aluminum Wire comes in two different standards; AWG (American Wire Gauge) or kcmil (kilo circular mils).

The American wire gauge designates how many amps a conductor can handle using this formula: A = 1728*f(d^2)/(32*pi^2).

Is copper wire safer than aluminum wire?

copper wire vs aluminum wire

These two types of wires are similar in resistance and can be used interchangeably with no ill effects, though aluminum will cost less due to its lower material costs.

Copper Wire: Rated at 100 amps and can carry anywhere between 80-95 Amps of continuously loaded current. Copper wire is more expensive than aluminum wire, but looks nicer when strung together on poles. Aluminum wire: Rated at 100 amps and can carry between 94-105 Amps of continuously loaded current. Aluminum wire is less expensive than copper wire, but looks uglier when strung together on poles.

Is aluminum the better choice for overhead power line conductors?

No, copper is the better choice because it has more conductivity than any other metal. This means that it will allow for more efficient transmission of electricity which in turn makes more economical sense for utility companies to use. Aluminum wire may be used as a cheaper substitute for copper wire, but its inferior conductivity means that it must be replaced with far greater frequency; this adds yet another expense to an already expensive project.

On icing conditions - under heavy snow at cold temperatures (below 10 degrees F) both aluminum and copper lose around 10% of their resistance. This means that at a given voltage, the current will be more than if no snow was on the wire. In practice this does not happen because very few HV lines are operated at a fixed voltage - they have droppers which control the voltage from line to line and from line to ground until it reaches the required level for that load on that circuit. Copper has higher conductivity, therefore copper wires of a given size give a lower temperature rise in normal conditions compared to aluminum wires of similar sized.

Difference between Single-phase and Three-phase

The main difference between these two types of circuits is the voltage level at which they operate. Single phase circuits operate at a nominal 120 VAC, whereas three phase circuits operate at a nominal 240 VAC (using two wires per leg). Three-phase circuits are used mainly in large commercial and industrial facilities, as well as in some utility substations. Single-phase circuits is

While copper is used primarily for residential electric service wiring, aluminum is the preferred material for commercial construction. Aluminum wires are good conductors of electricity, are light weight, are inexpensive compared to copper, are easily routed or concealed by cable-trays , conduit or raceways . They usually last longer than copper due to it's higher corrosion resistance characteristics. However they have limited temperature range compared to copper so must be carefully matched with connectors and devices which can withstand temperatures above 90C / 194F.


To conclude this blog post, aluminum wiring is a viable option for houses where copper prices are high, but the superheat requirement of aluminum wire limits it's use in some cases.

Thank you so much for reading this article on Aluminum Wire Vs Copper Wire For 100 Amp Service, hopefully you found it helpful and informative.

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