What Size Breaker Do I Use In The Main For A 100 Amp Subpanel

Looking for wire size for 100 amp service? If you are trying to set up a 100 amp conduit circuit, you lot will need to make sure to choose the right wire size. 100 amp circuit at 240V tin handle up to 24,000W of electricity.

Power = 100 Amps × 240V = 24,000W

In the Us, we have an AWG gauge organization for wire sizes. These wires range from the biggest 0000 AWG wire with 230 ampacity to the smallest forty AWG with less than 0.1 ampacity.

With 100 amps sub panel wire size, we go a number of different questions, such as:

What size wire for 100 amp service?
What size wire for 100 amp service 100 anxiety or 150 feet away?
What is the 100 amp breaker wire size?

Many homeowners use smaller #4 AWG and #ii AWG wires for 100 amp service and wonder why they fried their sub panel. To avoid frying your circuit, it's vital to account for ii central factors that come into play hither:

80% National Electric Lawmaking (NEC) requirement (NEC 220-two Code).
Distance from the sub panel due to the voltage drib (NEC 310-sixteen Code).

We will apply both of these factors when determining what size wire yous need for 100 amp service.

Here is how you adequately size a wire for 100 amp service:

First, check the wire gauge chart hither. Y'all have all the AWG copper wires and their ampacities listed (at median 75°C or 167°C temperature). From that chart, you can see that nosotros have 4 wire sizes with amps in the vicinity of 100 amps. These are:

At present, information technology seems that a #iii AWG wire with 100 ampacity is the perfect 100 amp wire size. That's a very common error. In fact, the most appropriate wire size for 100 amp service is the #1 AWG wire with 130 amp median capacity.

To empathise why this is, and what wire size you need for 100 amp sub panels 100 or 150 feet away, permit's look at the what the NEC code requirements are for 100 amp wire size:

100 Amp Wire Breaker Size With eighty% NEC Requirement

As yous can run across from the chart higher up, these are the wire ampacities in the vicinity of 100 amps:

#4 AWG can handle 85 amps.
#3 AWG tin handle 100 amps.
#2 AWG can handle 115 amps.
#1 AWG tin handle 130 amps.

Here is what NEC code says about 100 amp sub panel wire sizes:

Maximum loading for any branch circuit is eighty% of the rating of the circuit for ampacity of wire for any load. (NEC 220-2)

This is a rubber mensurate. You never put the circuit under 100% ampacity; at nearly you lot wire it to hitting 80% ampacity. For our wires, this is what the bodily ampacity is:

#4 AWG has 85A ampacity but should comport at most 68 amps.
#three AWG has 100A ampacity but should conduct at most fourscore amps.
#2 AWG has 115A ampacity but should conduct at well-nigh 92 amps.
#one AWG has 130A ampacity but should behave at most 104 amps.

As we tin run into, the #3 AWG wire might have 100A ampacity but it should only be used in circuits that require eighty amps or less.

With the 80% NEC rule, the best wire size for 100 amp service is #1 AWG.

Now, this is the right wire size for a sub panel that is shut to the electric device you want to run. What is the sub panel is 100 anxiety abroad? Yous will demand a bigger wire, and here's how you lot determine the 100 amp wire size for sub panel 100 feet abroad:

Wire Size For 100 Amp Sub Console 100 Feet Away

With distance, inevitably the voltage in the circuit drops. This driblet is insignificant at depression altitude (less than 3%) simply at longer distances similar 50, 100, or 150 anxiety, the voltage driblet is significant enough and you will have to business relationship for it.

To counter the 100 amp voltage drop, yous have to increase the amperage. The key question here is how much y'all accept to increase the amps to counter this voltage drop.

NEC 310-sixteen rule tells us that, roughly speaking, nosotros demand to increment the amps past xx% for every 100 feet of distance from the sub console.

Here's what that ways for a 100 amp sub panel 100 feet abroad (we have to account for 2 things):

Outset, nosotros need to business relationship for 80% NEC code as we did before.
On pinnacle of that, we need to account for this 20% voltage drib due to sending electricity 100 feet away.

Hither how we determine the ampacity we need from the wire:

Business relationship for fourscore% NEC code: At 0 feet distance, we demand 100 amps. This 100 amps should exist at most 80% of the ampacity of the wire. If 100 amps is 80%, what is the 100% wire size?

Min. Wire Ampacity = 100% × 100A / eighty% = 125 Amps

If the sub panel would be 0 anxiety away (very close) nosotros would need a minimum 125A wire.

Account for 100 feet away: Our sub panel is 100 feet away. That means we demand to boost the amps by an additional twenty%. How much does that get us?

Min. Wire Ampacity (100 ft away) = 125A × 1.2 = 150 Amps

That ways that we need a wire with at least 150 ampacity to evangelize 100 amp service 100 feet away. If yous check the wire size chart (you have the link in the introduction), the #0 AWG wire (also known as 1/0 AWG wire) has 150 ampacity. That means that #0 AWG wire is the perfect size wire for 100 amp service 100 feet away.

Using this kind of adding, you can pretty much determine which breaker size you need for 100 amp service at any distance. To illustrate, let'southward look at 150 anxiety altitude:

Wire Size For 150 Amp Sub Panel 100 Feet Abroad

Alright, every bit nosotros have calculated before, we demand at least 125 ampacity wire to handle 100 amp current. Now we need to add together the 30% amp boost (+20% per every 100 feet, hence +xxx% for 150 feet) to these 125 amps:

Min. Wire Ampacity (150 ft away) = 125A × 1.3 = 162.5 Amps

For sending 100 amps current 150 anxiety away, we need a wire with at to the lowest degree 162.five ampacity. If yous consult the wire gauge chart, y'all run across that the #0 wire can handle 150 amps. It's as well small-scale.

100 amp service 150 anxiety away from the sub panel requires #00 AWG wire (also known every bit two/0 AWG wire). This wire has a median ampacity of 175 amps; more enough than the required minimum 162.5 ampacity.

We promise all of this helps. If you lot haven't found the answer to your 100 amp question, you can use the comments beneath and nosotros'll try to aid you out. For 100 amp aluminum wires, you can consult the aluminum AWG wire chart.

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