Wire size for 100 amp subpanel (2024)

Wire size for 100 amp subpanel (1)

In addition to that, you should always follow the NEC rule when choosing the wire for a sub-panel. You need to choose the right type of wire for your electrical sub panel.īecause choosing the wrong wire may not be able to suit the electric flow and cause a lot of nuisances.

Wire size for 100 amp subpanel (2)

Generally, wiring is one of the most essential parts of electrical work that is being done to ensure proper power supply throughout the house. You should make sure that the wire you are using to run 100 amps up panel should be sufficient to the amperage of the sub panel to provide you with proper electricity flow. Generally, the wire that is suitable to run a 100amp subpanel is #4 copper wires or #2 aluminum wires. Generally, a 100 amp sub panel requires #4 copper wires or #2 aluminum wires. When choosing the wire for a 100 amp subpanel, you need to make sure that the wire gorge is sufficient for the amperage of the sub panel. Generally, the #4 AWG has 85A ampacity but should conduct at most 68 amps.

Wire size for 100 amp subpanel (3)

It is ideal to wire the circuit to hit 80% ampacity. When running the subpanel, you should never put the circuit under 100% ampacity. However, when adding or servicing a 100 Amp wire(s), it is highly recommended to consult and even hire a certified electrician who is aware of local standards and laws regarding electric wiring. So, if You need to know the solid copper wire thickness for 100 Amps service/sub-panel, then: When calculating the wire thickness of the long wires, always use values from the 60☌/140☏ column, since the "wire length" rule, especially after calculating the "80% Rule" is all about energy losses and not wire surface temperature - as long as the wires are properly installed. Now, we have to check the required AWG value for given wire lengths, depending on the wire surface temperature - values are given in the following chart: Wire Length / Surface feet (125 Amps) There are several rules and standards that may be used when calculating the required wire thickness, but the general rule of thumb is to increase the required Ampacity by 10% for every 50 feet (~15 m) of the wire length - some standards increase Ampacity by 20% for every 100 feet (~30 m) which provides the same or very similar results.įor example, when calculating the required Ampacity for the 50 feet, 100 feet, 150 feet, and 200 feet wires, we can use (default value is 125 Amp, after applying the "80% Rule"):ĥ0 feet wire: Ampacity = 125 Amps * 1.1 = 137.5 Ampsġ00 feet wire: Ampacity = 125 Amps * 1.2 = 150 Ampsġ50 feet wire: Ampacity = 125 Amps * 1.3 = 162.5 AmpsĢ00 feet wire: Ampacity = 125 Amps * 1.4 = 175 Amps 90☌/194☏: 2 gauge wire (AWG 2) features an Ampacity of 130A.Īnd these values are for relatively short wires, usually less than 50 feet (less than ~15 meters), which raises the question about the wire thickness of longer wires. 75☌/167☏: 1 gauge wire (AWG 1) features an Ampacity of 130A, 60☌/140☏: 0 gauge wire (AWG 0) features an Ampacity of 125A, Thus, for 100 Amp service, the required wire thickness is: Hence, we should not look for wires being able to carry 100 Amps, but 125 Amps:

Wire size for 100 amp subpanel (4)

The 80% Safety RuleĨ0% Rule states that actual wire current should be at most 80% of its default Ampacity. 90☌/194☏: 3 gauge wire (AWG 3) features an Ampacity of 115A.īut, these wire thicknesses are not recommended for actual use since wires should never carry current that equals their default values for safety reasons - hence the 80% Rule. 75☌/167☏: 3 gauge wire (AWG 3) features an Ampacity of 100A, 60☌/140☏: 1 gauge wire (AWG 1) features an Ampacity of 115A, Note: Ampacities are given for enclosed wires ambient temperatures.Īs one can see, the Ampacity of wires is given at three different temperatures (60☌/140☏, 75☌/167☏, and 90☌/194☏), but for most residential installations, 60☌/140☏ is the maximum allowed wire surface temperature.Īlso, if the value is not given for a required current, one has to look for a wire with a larger Ampacity.įor example, if we are going to look for 100 Amp wire size using default Ampacities for solid copper wire, then:

Wire size for 100 amp subpanel (2024)


Wire size for 100 amp subpanel? ›

100amps will require #3 copper and a #8 copper ground wire. Since it is a sub panel, 4 wires are required. 2 hots, a neutral, and a ground wire.

What size wire do I need to run for a 100 amp sub panel? ›

Most 100-amp service panels require #2 AWG wire. Electricians use these wires when there's significant space between the circuit breaker panel and electrical equipment (such as air conditioners), which is common in large commercial buildings.

Is 4 AWG good for 100 amps? ›

Typical sizes of wires for 100 Amp Service are 4 AWG or 2 AWG for copper wiring and 2 AWG, 1 AWG, or 1/0 AWG for aluminum or copper-clad wiring. These sizes are also used for direct burial. When choosing 100 amp service wire size, remember that a 100 amp circuit at 240V can proceed up to 24,000W of electricity.

Will 4 0 wire fit in a 100 amp breaker? ›

OK, A 100 amp breaker requires either 2 AWG copper or 1/0 AWG aluminum. Since your run is lengthy, you needed to upsize the feeder circuit in order to compensate for the voltage drop. You can purchase a multi-tap connector to make the connections. Run the 4/0 AWG aluminum feeder into the panel.

What size conduit for 100 amp service? ›


Can you run a 100 amp sub panel off a 100 amp main panel? ›

sure, I have two 100 Amp subpanels coming off a 100 Amp panel. Just so long as the subpanels are appropriately protected with breakers.

What size cable is used in 100A supply? ›

16mm2 cables used in 100A consumer unit.

How many amps can 4 0 wire handle? ›

Wire Size & Amp Ratings
17 more rows

Can I use 1 0 wire for a 200 amp panel? ›

When installing a 200 Amp service, you will need at least 3/0 AWG copper wire or 4/0 AWG aluminum or aluminum copper-clad wire.

Does subpanel wiring need to be in conduit? ›

Service entrance SER cable is a very popular option for a subpanel. After all, subpanels are one of the main types of applications for this cable. SER is a non-expensive option that gets the job done incredibly well. No conduit is needed, even outdoors.

What size Romex connector for 100 amp service? ›

Wire SizeAmpsWire Type
3 Gauge100 AmpsService entrance and feeder wire
6 Gauge55 AmpsFeeder and large appliance wire
8 Gauge40 AmpsFeeder and large appliance wire
10 Gauge30 AmpsDryers, appliances, and air conditioning
4 more rows

What is the max breaker size on 100 amp service? ›

The National Electric Code (NEC) stipulates that a 100 Amp panel can accommodate up to 42 breakers as the maximum. Still, it's essential to understand that this is a theoretical limit. Not every breaker can operate at full capacity all the time.

How many ground rods for a 100 amp sub panel? ›

In just about all cases, for an outbuilding, you need 2 ground rods at least 8' long spaced at least 6' apart (further is better). There is a ton of info here on SE regarding sub-panels. Do a quick search and you'll find everything you need to know.

How many circuits can be on a 100 amp sub panel? ›

Nevertheless, a standard 100 Amp panel typically supports a minimum of 20 circuits, equivalent to 20 regular circuit breakers. The National Electric Code (NEC) stipulates that a 100 Amp panel can accommodate up to 42 breakers as the maximum.

How many amps for 6 gauge wire? ›

Note that the ampacity of the wire can be reduced if the cable is bundled with other cables or is placed in high ambient temperatures. However, the regular ampacity of a 6 AWG copper wire that you are looking at in most installations is 55 to 65 amps. It can carry 55 amps, 60 amps, and 65 amps.

Can I use aluminum wire to feed a subpanel? ›

Safety concerns caused aluminum wire to be banned from use in branch circuits years ago, but it is a common option for feeding main service panels and subpanels.


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