What Size Copper Wire For 100 Amp Sub Panel

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

Ability = 100 Amps × 240V = 24,000W

In the US, nosotros have an AWG approximate arrangement for wire sizes. These wires range from the biggest 0000 AWG wire with 230 ampacity to the smallest 40 AWG with less than 0.i ampacity.

With 100 amps sub panel wire size, we become a number of dissimilar questions, such every bit:

What size wire for 100 amp service?
What size wire for 100 amp service 100 feet 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, information technology's vital to account for two key factors that come up into play hither:

80% National Electric Lawmaking (NEC) requirement (NEC 220-2 Code).
Distance from the sub panel due to the voltage drop (NEC 310-xvi Code).

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

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

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

Now, it seems that a #3 AWG wire with 100 ampacity is the perfect 100 amp wire size. That'due south a very common mistake. In fact, the about appropriate wire size for 100 amp service is the #1 AWG wire with 130 amp median capacity.

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

100 Amp Wire Billow Size With 80% NEC Requirement

As you lot can run into from the chart higher up, these are the wire ampacities in the vicinity of 100 amps:

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

Hither is what NEC code says nigh 100 amp sub panel wire sizes:

Maximum loading for whatever branch excursion is 80% of the rating of the circuit for ampacity of wire for any load. (NEC 220-2)

This is a safety measure. Y'all never put the circuit nether 100% ampacity; at nigh you wire it to hit 80% ampacity. For our wires, this is what the actual ampacity is:

#4 AWG has 85A ampacity but should comport at most 68 amps.
#3 AWG has 100A ampacity but should conduct at most eighty amps.
#ii AWG has 115A ampacity simply should conduct at most 92 amps.
#1 AWG has 130A ampacity but should behave at about 104 amps.

As we tin can see, the #3 AWG wire might have 100A ampacity but it should only exist used in circuits that require lxxx amps or less.

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

At present, this is the correct wire size for a sub panel that is close to the electric device yous want to run. What is the sub console is 100 feet away? Yous will need a bigger wire, and here's how yous decide the 100 amp wire size for sub panel 100 feet away:

Wire Size For 100 Amp Sub Panel 100 Feet Away

With distance, inevitably the voltage in the circuit drops. This drib is insignificant at low altitude (less than iii%) merely at longer distances like 50, 100, or 150 feet, the voltage drop is meaning enough and you will take to business relationship for it.

To counter the 100 amp voltage drop, you have to increase the amperage. The key question here is how much you have to increment the amps to counter this voltage drop.

NEC 310-16 rule tells usa that, roughly speaking, we need to increase the amps past xx% for every 100 feet of altitude from the sub panel.

Here's what that means for a 100 amp sub panel 100 feet away (we take to account for 2 things):

Offset, we need to account for 80% NEC code as we did before.
On top of that, we demand to account for this twenty% voltage driblet due to sending electricity 100 anxiety away.

Here how we determine the ampacity we demand from the wire:

Account for fourscore% NEC code: At 0 feet distance, we need 100 amps. This 100 amps should exist at almost lxxx% of the ampacity of the wire. If 100 amps is fourscore%, what is the 100% wire size?

Min. Wire Ampacity = 100% × 100A / 80% = 125 Amps

If the sub console would be 0 anxiety abroad (very close) we would demand a minimum 125A wire.

Account for 100 anxiety away: Our sub panel is 100 feet away. That ways nosotros need to boost the amps past an boosted 20%. How much does that get united states of america?

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

That means that we need a wire with at least 150 ampacity to deliver 100 amp service 100 feet abroad. If you cheque the wire size nautical chart (yous 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 anxiety away.

Using this kind of calculation, you lot tin pretty much determine which billow size you need for 100 amp service at any distance. To illustrate, let's wait at 150 feet distance:

Wire Size For 150 Amp Sub Console 100 Anxiety Away

Alright, every bit we have calculated earlier, we demand at least 125 ampacity wire to handle 100 amp electric current. At present we need to add together the thirty% amp boost (+20% per every 100 anxiety, hence +xxx% for 150 anxiety) to these 125 amps:

Min. Wire Ampacity (150 ft away) = 125A × ane.three = 162.five Amps

For sending 100 amps electric current 150 feet away, we need a wire with at least 162.5 ampacity. If you consult the wire gauge nautical chart, yous run across that the #0 wire tin can handle 150 amps. It's too pocket-sized.

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

We hope all of this helps. If you oasis't constitute the answer to your 100 amp question, you can use the comments beneath and we'll try to help yous out. For 100 amp aluminum wires, you can consult the aluminum AWG wire nautical chart.

It might also be helpful to read some of our related articles on like topics, including:

20 amp wire size.
30 amp wire size.
40 amp wire size.
50 amp wire size + sub console at a 100 feet distance.
lx amp wire size + sub panel at a 100 feet distance.
200 amp wire size.