What Gauge Wire for 1000 Watt Amplifier

Every now and then We get e-mails and comments from greenhorn car audio enthusiasts who need help with car audio related stuff. One recent one asked, “What gauge wire should I use for 1000 watt amp?”.

Well, it goes without saying that when installing a car amplifier, having the correct wire connections is very important. In fact, proper audio wiring is almost as important to the performance of an audio system as the amps, speakers, and subs used in the system.

Higher quality wiring is the key to making sure your amplifier is getting the power it needs to run efficiently and provide reliable power.

These are but some of the most common questions we get asked most often. So, instead of replying to each person individually with the same information, I figured I would do an official post so that it could live on forever.

So, without any further ado, let’s get into it…

Why Using the Right Size Wire Matters?

Car amplifiers can draw a substantial amount of current from the electrical system when the volume is cranked. This is the reason why it’s so important to wire them correctly to get the best performance.

To ensure that your amplifier is operating properly and to its full output potential, its power and ground cables need to be large enough to handle the amplifier’s demand for electrical current.

Choosing the correct wire gauge (thickness) to use for power cabling depends on the current draw of your amp, and on the length of the wiring.

Generally speaking, the more power demanding the audio system, the larger gauge wire you will need to use.

Using a proper gauge power wire is critical to ensuring smooth current flow, and improving the reliability of your overall system.

I mean, think about, if your amp power wires aren’t thick enough, your amp might not get adequate power supply which could result in the amplifier cutting out at higher volumes.

Using a proper gauge power wire is also critical to ensuring the safety of your audio system and your car, as smaller gauge wire under current overloads can potentially overheat to the danger point. In other words, if the flow of current exceeds the wire’s specifications, the internal wire starts to heat up, which could melt the wire and cause fire.

A general guideline for choosing the required gauge wire is as follows:

How to Figure out Amp Current Draw

The chart above is a general guideline and can be used as a quick reference in determining the appropriate wire gauge.

For a more detailed formula in determining the wire gauge size needed for an amplifier, follow the steps below.

By following these steps, you can factor in the length of the cable. This is a more accurate way in finding out what gauge of wire you need.

So, let’s determine what gauge wire to use for your amplifier.

First of all, in order to determine the approximate current draw (in amperes) of your amplifier, you must first calculate the total power of the system.

To do that, multiply the number of channels your amplifier has by the number of RMS watts per channel. For example, if you have a 4-channel amplifier rated at 60 watts RMS per channel, the total power for the system is: 4 channels * 60 watts = 240 watts RMS.

If you have multiple amps, add up the total RMS power figures to arrive at a grand total. If you only have one mono channel amplifier, then the RMS power of the single channel will be the wattage you will reference.

Generally speaking, there are two types of amplifiers – Class D and Class AB amps – so there are two formulas for calculating the approximate current draw (more on this down below).

Check which class your amplifier is and use the adequate formula. You can usually find this information listed on the amplifier label, or in the owner’s manual. If you don’t know what Class your amplifier is, use the class AB calculations for the safest result.

General Formula: [(Total RMS wattage / Amp Efficiency) / 13.8 Volts)]

Class D amplifier formula: [(Total RMS wattage / 0.90%) / 13.8]

Class AB amplifier formula: [(Total RMS wattage / 0.65%) / 13.8]

The resulting figure is your system’s approximate maximum current draw. You’ll need to compare it to the numbers in the “Amperes” column in the chart below to figure out which gauge of cable you need.

Next, you’ll need to figure out the cable length. To do that, run a string from your battery to the amplifier’s mounting location. Measure the string and add a fair amount of extra length. This will provide some slack for easier connection to your amp.

Finally, cross-reference these two figures in the chart to determine the proper gauge power wire to use for your amplifier.

Wire Size Calculator

These tabulated values are for stranded copper wire only. Copper-clad aluminum (CCA) wire cannot handle the amount of current that a copper wire of the same size can.

A More Detailed Explanation

Here’s a detailed explanation about the aforementioned formulas in case you want more details. Calculating the amplifier’s total power is a no brainer, but the other parts can be confusing.

Calculating Current: Joule’s Law

To determine the amp draw of any equipment, you will need 2 pieces of information. First, you need to know the voltage (V) going to the equipment. And second, you need to know the wattage output of the electronic equipment you will be using. Then you take the wattage, and divide it by the voltage (120 watts / 12 volts = 10 amps.) This will tell you roughly the amperage your equipment will draw.

Current (Amperes) = Power (Watts) / Voltage (Volts)

No amplifier is 100% efficient

The above formula is correct, but it doesn’t take into account your amplifier’s efficiency rating. The latter refers to the ratio of power input (from the battery) to power output (to the speakers). And That needs to get factored in to accurately figure out your amp’s current draw.

No amplifier is 100% efficient, putting out exactly what it draws. The power that doesn’t make it to the output terminals is wasted energy because it doesn’t contribute to driving the load.

The wasted energy turns into heat, which must be dissipated into air because otherwise it will destroy the amplifier’s output signal and internal components.

This is the formula we use to factor in amp’s inefficiency:

Current (Amperes) = [(power / amp efficiency) / Voltage]

Power (Watts) divided by Amp Efficiency (X%) divided by Voltage (Volts)

By factoring in amp’s inefficiency for each class of amplifier, we arrive at the two formulas listed above:

The formula for Class D amps

Class D amplifiers are the popular kings of efficiency. They boast an efficiency rating of up to 90%, which means about 90% of the power it generates is turned into audio output while only 10% of the power is lost as heat. So if the amplifier has a total a power output of 800 watts, it’s actually drawing about about 888 watts of power from the electrical system. Thus, the amp’s wiring need to big large enough to handle the draw.

• Class D amplifier’s Current Draw = [(total RMS output / 90% Efficiency) / 13.8 Volts]

The formula for Class AB amps

Class AB amplifiers are about 65% efficient. This means about 65% the power it generates is is turned into audio output while the remaining 35% of the power is lost as heat.

So if the amplifier is putting out 800 watts, it’s actually drawing about 1230 watts of power from the electrical system. Therefore the amp’s wiring needs to be big enough to handle that draw.

• A Class AB amplifier’s Current Draw = [(total RMS output / 65% Efficiency) / 13.8 Volts]

Automotive voltage is not constant

Vehicles have a 12-volt electrical system. But when the engine is running, the alternator will bump up the system voltage to about 13.8 volts.

In fact, 13.8V is the standard voltage of an automotive electrical system with the engine running.

Car amplifier manufacturers use 14.4 Volts, when they rate their amps, to exaggerate their power ratings. So, since you car won’t put out the 14.4V that most amplifiers use for their ratings, we will use 13.8V, which is a better real-world representation of the vehicle’s electrical supply.

Resistance increases with wire length

The main electrical property of a cable is the resistance that it shows to the flow of electrical current.

Wire resistance goes hand in hand with the wire thickness and ­length. A longer thinner wire has much more resistance than a shorter thicker wire of the same structure. That is to say, the resistance builds up as the wire gets longer, until it forces the voltage to drop below a useable level. At that point, using a larger gauge wire is mandatory in order to restore the voltage to its intended level.

Wire size matters for current flow

Last but no least, the primary performance limitation we most often come cross when it comes to amplifier installations is in the lack of current delivery because by either a weak ground or insufficient wire gauge.

Obviously, using a wire gauge that’s too small results in poor performance, and holds your audio system back reaching its full potential and sounding good, which can turn it into an expensive disappointment.

Using a small gauge wire can also damage your equipment, and poses a potential safety hazard.

On the other hand, using gauge wire that’s too large doesn’t really have any downside. However, it doesn’t make sense to splurge on thicker gauge wire where a thin wire would suffice. That kind of overkill would be a waste of money.

FAQ

What gauge wire for 1000 watt amp?

Now that you have some idea of how to determine what gauge wire to use for your amp, let’s answer the question of “what gauge wire for 1000 watt amp?”

Let’s suppose you have a class D subwoofer amplifier with an RMS rating of 1000 watts. The amplifier is mounted in the trunk and the distance between the battery and the where the amp is mounted is roughly 12 feet.

So, let’s calculate the current draw of your amp using the formula for Class D amps.

• Current Draw = [(1000 watts / 0.90% amp efficiency) / 13.8 Volts]
• Current Draw = [1111 / 13.8]
• Current Draw = 80 Amperes

Now, if we cross-reference the current draw of 80 Amperes and the 12 feet wire length, the result would be 4 gauge wire.

What gauge wire for 1200 watt amp?

Let’s suppose that you have a 2 channel class AB amplifier rated at 600 watts RMS per channel, and is mounted 16 feet away from the battery. What gauge wire is adequate for this amp ?

Well, first of all, we need to determine the total power output for this amplifier.

2 channels * 600 watts = 1200 watts RMS.

Next, let’s calculate the current draw of your amp using the formula for Class AB amps.

• Current Draw = [(1200 watts / 65% amp efficiency) / 13.8 Volts]
• Current Draw = [1846 / 13.8]
• Current Draw = 133 Amperes

If we cross-reference this amplifier’s current draw of 133 Amperes and the 16 feet wire length, we would get 2 gauge wire.

What gauge wire for 2000 watt amp?

Let’s assume that you have a class D amplifier rated at 2000 watts RMS mounted 20 feet away from the battery. What gauge wire is adequate for this amplifier ?

Let’s calculate the current draw of your amp using the formula for Class D amps.

• Current Draw = [(2000 watts / 90% amp efficiency) / 13.8 Volts]
• Current Draw = [2222 / 13.8]
• Current Draw = 161 Amperes

If we cross-reference the current draw of 161 Amperes and the 20 feet wire length, we would get 1/0 gauge wire.

What gauge wire for 3000 watt amp?

Let’s suppose you have class D amplifier with an RMS rating of 3000 watts. The amplifier is mounted 8 feet away from the battery. What gauge wire is adequate for this amp ?

Let’s calculate the current draw of your amp using the formula for Class D amps.

• Current Draw = [(3000 watts / 90% amp efficiency) / 13.8 Volts]
• Current Draw = [3333 / 13.8]
• Current Draw = 241 Amperes

If we cross-reference the current draw of 241 Amperes and the 8 feet wire length, we would get 2 gauge wire.