Having the correct wire size is essential, particularly when it comes to safety, which leads us to ask – what wire size do you need for 60 amps?
A common mistake amongst many homeowners is using a 6 AWG wire for a 60 amp breaker, simply because a 6 AWG gauge wire has a 65 A ampacity.
This makes sense at first, and it is definitely an understandable error to make. However, the problem is that doing this causes your 60 amp breaker to fry.
But after reading this article, you won’t ever make that mistake again! Before we answer what wire size you need for 60 amps though, let’s define a few key terms first.
What Is Ampacity?
Ampacity is the total amount of current that a wire or cable can safely carry.
We can consider ampacity as the maximum amount of current that can run through a certain wire size with voltage and temperature drop at the limits.
You shouldn’t judge wire size just by length though. The longer the run, the greater the distance between your panel and subpanel, or load location to subpanel, will need bigger conductors.
To avoid larger voltage drops it’s important to take ampacity seriously and select wire size accordingly.
What Is Gauge?
It’s also important to define what gauge is too. Gauge doesn’t just refer to the size of the conductor (its physical dimensions).
Instead, it only reflects the amount of electrical current that can safely flow through it in specific conditions such as the insulation type, operating temperature, and operating voltage.
Most electrical conductors have some kind of insulation to stop the electric current from directly passing through them.
An insulator is essential, as the flow of the electric current will heat up the conductor as it passes through, which can damage or melt the wire.
Because the size of a material’s cross-section is often essential in how well it carries out this function, this is why it’s referred to as ‘gauge.’
What Is The Right Size For A 60-Amp Breaker?
A 4 AWG wire is the right size for a 60 amp breaker.
Resistance will cause the wire to heat up too much when the optimal current level according the breaker’s ranking flows through it if you use wire with an insufficient amperage.
This can be a fire hazard, and nobody wants that!
Meanwhile, a heavy-gauge is challenging to deal with, is expensive, and hard to connect or link. Therefore, it’s important not to use a wire that is too big.
What Wire Size Should You Use For A 60 Amp Subpanel?
If you have a short run of wire, then a 6 AWG wire is acceptable. However, because of the voltage drop, if you decide to go more than 100 feet, then you should still go for a 4 AWG wire.
What Happens If You Use The Incorrect Size For Your Breaker?
A variety of outcomes are possible if you use the incorrect wire size for a 60 amp (see also: What Size Wire For 20 Amp Wire Size)breaker. If you use a wire size that is too large for a 60 amp breaker, then the outcome will not be too dramatic.
The larger wire will just not be value for money. But if you use a wire that is too small for your 60 amp breaker, then a lot can go wrong.
Safety is the main reason why you should get the correct wire size for your breakers.
The wire size determines whether the wire conductors can take the amperage that will flow through it.
If a wire isn’t equipped to take a particular amperage, then it may melt or even burn the wire, potentially resulting in a fire that could do serious damage to your home and your safety.
For this reason, it’s important to be very conscious of the accurate wire sizes and their ability to carry amperage load.
Generally, the bigger and thicker wire sizes are better able to handle larger amperage loads, as they can mitigate the excessive heat created by the electricity flowing through the cable.
NEC Code Rules
Rule 1: 80% Breaker Rating Rule For 60 Amp Wire Sizing
If you’re not that knowledgeable about wire sizing, then it’s understandable why you might use a 6 AWG wire for a 60 amp breaker.
After all, if a 6 AWG wire has a 65A ampacity, then you just need 60 amps for a 60 amp breaker, right? But, as we have seen, this is not the case.
The 80% breaker resting rule is the most important rule in wire sizing. This rule ensures electrical safety by preventing the frying of electrical circuits caused by wire gauges that are too small.
Let’s take a closer look at how the rule works.
If you want to determine the wire gauge for the 60 amp breaker – whether that be a 60 amp service or a 60 amp hot tub wire size – (see also: What Size Wire For A 100 Amp Service)then 60 amps is 80% of the wire size you need(see also: What Size Wire Do You Need For A 40 Amp Breaker?)(see also: What Size Wire Do You Need For A 40 Amp Breaker?)(see also: What Size Wire Do You Need For A 40 Amp Breaker?).
So, for a 60 amp breaker you will need a wire that can handle a minimum of 75 amps. So let’s take a look at how you make this crucial calculation.
Adequate Wire Size = 60 amps ÷ 0.8 = 75 amps
The fact that 6 AWG can only handle 65 amps is unfortunately something that most amateurs don’t take into account.
However, a professional will know that the other wire size that can handle over 75 amps (that you need for a 60 amp breaker) is the 4 AWG gauge wire.
A 4 AWG wire can handle 85 amps, which is plenty of ampacity to sufficiently wire a 60 amp breaker, even when you take the 80% breaker rule into account.
This principle also applies for direct burial wire size and free air wire size calculation.
In some rare cases however, a 3 AWG wire size can be used for a 60 amp breaker, because of the second NEC code rule.
Rule 2: Account For Voltage Drop
You don’t have to worry about losing voltage if you have a short circuit. Still, if you have a long wire connecting to a 60 amp breaker, then you need to take the voltage drop into account.
When you ignore the voltage drop, then you may accidentally use a regular 4 AWG gauge wire when you should actually use a larger 3 AWG wire.
Let’s take a look at the general rule for voltage drop that you should be using.
For every 100 feet of wire, the voltage drops by 20%.
Factors such as the choice of wire (aluminum, copper, iron, and steel), and the amount of wires may impact the exact percentage loss, but this is the basic rule of thumb.
Therefore, we should increase the amps by 20% for every 100 feet of wire if we want the same power output (wattage) according to the basic electric power equation:
Power (Watts) = Current (Amps) × Voltage (Volts)
Let’s look at an example to demonstrate what a voltage drop is and how to work out the wire size for a 60 amp breaker that is a considerable distance away from the source of power.
What Is A Wire Size For A 60 Amp Sub-Panel 150 Feet Away?
Taking the 80% breaker rating rule into account, we are aware we need a wire that is able to handle a minimum of 75 amps. But now, we need to add the amps to balance out the drop in voltage.
According to the basic rule of voltage loss, we lose 30% of voltage in 150 feet of wire (100 feet = 20%, 150 feet = 30% loss). This means we need to boost the amps by 30%.
Let’s take a look at how to calculate the final amps:
75 amps × 1.3 = 97.5 amps
This means that a wire for a 60 amp sub-panel that is 150 feet away can handle a minimum of 97.5 amps, a 6 AWG wire can take 65 amps, and a 4 AWG wire can take 85 amps.
In this instance, because of the 150 feet distance, both of the wires have an insufficient amperage.
Therefore, we need to go for the next available wire size – 3 AWG. This wire size can take up to 100 amps, making it perfect.
Basically, the correct wire size for a 60 amp sub-panel that is 150 feet away would be A 3 AWG gauge wire.
60 Amp Vs 50 Amp Wire Size
The correct wire size for a 60 amp and a 50 amp is pretty much the same, in that 4 AWG is sufficient for both.
However, the differences with a 50 amp wire is the fact that a 50 amp will need a THHN wire and the 60 amp wire will need a THWN wire, and also the price.
The wire is normally decided by the National Electric Code (NEC).
The most common electrical cable sizes are referred to collectively as ‘NEMA wire sizing’ or NEMA sizes.
There are around 44 standard types of wiring metal, divided into different categories.
Also known as Ovally or Schedule 80, this is an oval conduit. Its shape provides the internal volume of the piping. These are most often used for lighting and power circuits.
Usually a copper clad steel wire, this is the most popular type of wiring found in commercial and residential buildings.
This is also known as THWN or Type THHN. It has a thin poly-vinyl outer layer with a thick, high-density black matrix armor, or rubber.
It is usually rated between 600v and 100v d.c., but it can be more depending on what it’s being used for.
Much like there are different kinds of conduits like flexible metal and rigid metal, there are two kinds of THW – Loose tube (armored) and Standard tube.
This category includes larger wire types, normally intended for placement underground.
They’re often grouped with other designations so it looks like: THHN/THWN or THW/THWN-2.
Conductor Wires (AWG)
Standing for American Wire Gauge size, this is a standardized unit of measurement for electrical conductors, also known as the American Standard.
However, it is also used in Japan as well as North America. The lower the gauge number, the larger the AWG and its diameter.
This is also known as ‘armored’ capable – depending on what it’s being used for.
Just like there are different kinds of conduit, like flexible and rigid metal, there are two kinds of THW, loose tube and standard.
This is wiring covered in rubber that is often used for household appliances like lawn mowers and vacuum cleaners.
This type of wire is slowly going out of use due to its poor bandwidth capabilities (200MHz).
It also has a rather high signal attenuation because of the plain wire and 4-pairs in the cable, compared to 8-pairs of RG-59/U used in analog TV coaxial cable lines that have less attenuation.
Because of this, it was better suited for running a dedicated line for every device, or to power devices via a Powerline or a PC.
Still, Cat-5 is popular if you need to plug into a network hub that doesn’t support wireless connections and only has ethernet ports.
Cat-6 is set to replace Cat-5 wiring eventually, but this has been a slow process.
While it has fewer limitations of Cat-5 (as it can go up to 500MHz), but there are still pretty few deployments in which it is used over fiber optic lines or RG-59/U coaxial cables since its increase in bandwidth sacrifices long distance transmission when compared to Cat-5.
Also known as ‘NMD’ Romex wires have a black rubber sheath and twisted copper (or aluminum) conductors.
Romex is only rated up to 150 volts, so it’s important to know the difference between Romex and other wires on this list.
Unless you’re just going to be using a system that will not go over 150 volts, then Romex is a great choice.
We hope our article has clarified what wire size you need for 60 amps, why it’s so important to get the right wire size, the important NEC rules, and how to be safe when using certain wire sizes.
Knowing the correct gauge wire you need for your next project is essential, not just for your project to be successful, but safe too.
Before you take on any DIY electrical project, make sure you have done all the homework you need to do in order to be safe.
If you’re not confident a project is something you can do by yourself, make sure to hire a professional.
Being aware of what wire size you need isn’t something you instinctively know, and it’s something many amateurs and DIY enthusiasts get wrong – and there is no shame in that!
But hopefully our article has highlighted key differences in wire categories, wire sizes, and wire gauges so you can get the best out of your projects.
Good luck, and make sure to check out our other articles on wire sizes for other amps so you’re prepared for every electrical project you take on!