Electricity

TL;DR

 * If you got X generators of Tier Y, use cables that can handle X Amperes of Tier Y.

Voltage and Amperage
GregTech uses the terms Voltage (V) and Amperage (A) to describe its power system - GT Enet API (Enet). One "Amp" is roughly the same as one EU Packet from IC2, and "Voltage" is the size of that packet. EU stands for "Energy Unit".

EU/t is the total EU received. For example, if a machine receives one 32V packet and another 24V packet, the total EU/t received is 32 + 24 = 56 EU/t.

Unlike the IC2 energy system, all GregTech energy-interacting blocks have limits on both the Voltage and the Amperage they can interact with. Enet power is compatible with GregTech, IC2 and Redstone Flux (RF) consumers. The EU to RF conversion rate is 1 EU = 3.6 RF. This is a one-way conversion; RF generators cannot connect to Enet systems.

Different machine blocks accept and emit different Amperages.
 * GregTech Transformers will input 4A and output 1A if used to step-up Voltages; they will input 1A and output 4A if used to step-down.
 * Battery Buffers input 2A per Battery and output 1A per Battery.
 * Battery Chargers input 8A per Battery and output 4A per Battery.
 * Chest Buffers and Super Buffers accept 2A.
 * Energy Hatches accept 2A input.
 * Mass Fabricators accept 10A input.
 * Microwave Energy Transmitters accept 3A input.
 * Monster Repellators, Pumps, and Teleporters accept 2A input.
 * All other EU accepting machine blocks accept at least 1A, depending on recipe: The amperage is equal to twice the recipe's EU usage, divided by the machine's voltage input, rounded down and added to 1.
 * An LV Centrifuge performing a 5 EU recipe accepts 1A
 * An LV Chemical Reactor performing a 30EU recipe accepts 2A
 * An LV Arc Furnace performing a 96EU recipe accepts 7A
 * Generators output 1A.

You do need to be careful when trying to power machines:
 * Machines that get a higher Voltage than they can handle explode. Machines will not receive voltage until they need it, so the machine may not actually explode until it begins working!
 * Excess Amperes fed into machines have no effect as long as the voltage is below the machines' limit. A machine will not draw current unless it needs power, and it will not draw fractions of an ampere. This makes machines self-regulating with regards to power.

Machines and recipes each have voltage tiers. The tier of a Multiblock Machine is determined by its Energy Hatches. Machine and recipe tiers do interact, and must be paid attention to.

Recipes will be overclocked once per Voltage Tier difference between the machine's supplied Voltage Tier and the recipe's required one. If a recipe requiring 30 EU/t (LV tier) for 20 seconds is performed in an HV machine, the difference of 2 tiers will cause the recipe to use 480 EU/t for 5 seconds.
 * If a recipe has a minimum required voltage within a higher tier than that of the machine, the recipe cannot be carried out.
 * If a recipe has a minimum required voltage within the same tier as the machine, the recipe functions normally.
 * If a recipe has a minimum required voltage within a lower tier than that of the machine, the recipe is overclocked. Overclocked recipes are carried out at double normal speed, double normal total energy, and thus quadruple normal energy per tick.

GregTech: New Horizons has 9 finished Voltage Tiers as of version 2.0.2.5, it also has 3 Voltage Tier partial finished voltage levels(*) and 4 not reachable voltage levels(**).

Note: ULV Tier counts as Tier 0.

Cables and Loss
Given that GregTech has its own power system now, you will need to use GT cables for powering GT machines. Do note that the only machine capable of accepting IC2 EU in GT is the Transformer (Not to be confused with the IC2 Transformer).

All GT Cables have a max Voltage, max Amperage and a Loss: Do note that machines can request more Amperage than strictly required by their active recipe when their energy buffer is empty. For example a 32V package is sent trough a Tin Cable which has a loss of 1EU per block to a machine 8 blocks away. After 8 blocks of cables the 32V Package is down to 24V when it arrives at the machine. Should the machine need for example 30EU/t to operate. A second package sent in the same tick is needed every 4 Ticks. Thus a 2A supply is needed for the machine with this setup. Cable losses are applied to each EU Package, netting you a 2x power loss.
 * Cables that get packets higher than their maximum Voltage will catch fire and melt.
 * Cables that have more Amperes travelling through them than their maximum Amperage limit will catch fire and melt.
 * The loss of a cable is per Block a EU package travels.

Each Material has 1x, 2x, 4x, 8x 12x and 16x uninsulated Wires and most of them 1x, 2x, 4x, 8x, 12x and 16x Insulated Cables.

Do note that Uninsulated Wires have 2x the loss as Insulated Cables.

Here is an example:
 * A 1x Tin Cable can handle 1A and 32V at a loss of 1V/m. This means that the EU packet can travel 32 blocks before it dies.
 * A 1x Tin Wire can handle 1A and 32V at a loss of 2V/m. In this case, the EU can travel 16 blocks only.

Below is a table of the current properties of various types of cables in GregTech:

(*No insulated Cable version)

Also any GT Block and Battery outputting Energy has an energy loss on output. This means there is no such thing as lossless cables in GregTech.

A power outputting machine will take $$8\times4^{tier}+2^{max(0, tier-1)}$$ EU from its storage and output only $$8\times4^{tier}$$ EU. The energy lost is therefore $$2^{max(0, tier-1)}$$. ULV, being the lowest tier possible, is a bit special. It has the same loss value as LV, i.e. 1 EU.

An example: Say a turbine is supposed to output 32V.

$$output=32=8\times4^{tier}$$.

Solving for Tier gives you 1. The energy loss will then be $$2^{tier-1}$$. In this case it is 1.

So the turbine takes 33 EU from its storage, voids 1 EU per packet and then outputs 32 EU.

Here is a table documenting some of the cable properties in GregTech:

Optimal Cable length between Batteries for maximum efficiency.

The EU loss of GregTech Cables and Batteries scales linearly with the number of sequential Cables and the number of Batteries, but since voltage is topped up at every battery there will be a loss that is increasing exponentially for every identical segment of a Battery and x-number of Cable links. This exponential loss from more batteries also reduces the impact of the linear loss, but this ofc comes at the cost of more exponential loss. This means that there must exist a sweet spot, because with short segments the extra exponential loss of more segments will be more detrimental to the efficiency than the linear loss from making each segment longer, for long segments this will be reversed. So let's do the math!

Let's first define our terms, a segment is the length of a Battery plus a number of sequential Cables. The efficiency of such a segment will be $$\frac{8\times4^T-(D-1)\times L}{8\times4^T+2^{T-1}}$$. T is the tier (LV is tier 1, MV is tier 2, and so on). L is the loss of the cable in voltage/meter/ampere. D is the distance of the segment, so the length of the Cables plus the battery.

But this is no good since we want to figure out the optimal length when there is an element of exponential decline that we haven't accounted for. We do this by making an expression of how much efficiency we get in each single block if there was a uniform exponential decline over the whole segment. This turns out to be $$\left(\frac{8\times4^T-(D-1)\times L}{8\times4^T+2^{T-1}}\right)^\frac{1}{D}$$.

We now take the derivative of that expression with respect to D to get how the efficiency changes when we change the length of the segments, when we do this we get such a ghastly monstrosity that not even WolframAlpha can deal with it algebraically. But this won't stop us on our quest for efficiency! Lets solve it numerically!

Step 1: go to http://www.wolframalpha.com/ because we are lazy. Step 2: Enter "(d/dD) ((8 * 4^T - (D - 1)L) / (8 * 4^T + 2^(T - 1)))^(1 / D) = 0, T=, L=". It will solve the problem numerically for each separate case. So if you want to know the optimal length of Annealed Copper Cable between your MV Batteries, you enter T=2, L=1 and it will give you the optimal length of each segment (This includes the battery!). In the case of Annealed Copper Cable this turns out to be about 14.7876, so 24 cables between each battery is optimal. For more information on other cables, see the table above.

Transformers
Once you have crafted your first EBF and started MV tier, you will gain access to producing MV (Medium Voltage, 128V) which is great! However. You will need to transform this energy into LV power to use it with your existing LV machines since LV Machines will explode if they are given too high voltage.

The Transformer allows you to convert GT Energy between voltage tiers. The big hollow circle is the Higher voltage side and is the front of the transformer, while the 5 smaller circles are the lower voltage sides.

By default the Transformer is taking 1 amp of higher voltage and transforms it into 4 amps of lower voltage. This is also called Step-Down mode. Ingame it will say “Machine Active” when toggling to this mode. You can also right click the transformer with a Soft Mallet to switch between its two modes. In Inverted mode, Step-Up mode (“Machine Inactive”), the Transformer will take 4 amps of lower Voltage and transform it into 1 amp of Higher voltage. Keep in mind that in this mode the lower voltage sides become the Input, and the higher voltage side is therefore the Output.

You should never change mode on a transformer that has power. Always disconnect cables before switching mode on the Transformers.

Power Transformer and Hi-Amp Transformer
The Power Transformer and the Hi-Amp Transformer work like an ordinary transformer with one exception:

The Hi-Amp Transformer will accept 4 amps of higher voltage and turn it into 16 amps of lower voltage in its default mode. In inverted mode it will transform 16amps lower voltage to 4 amps of higher voltage.

The Power Transformer will accept 16 amps of higher voltage and turn it into 64 amps of lower voltage in its default mode. In inverted mode it will transform 64 amps lower voltage to 16 amps of higher voltage.

Machine explosions and cables burning
Using GregTech machines without thought and care can be fairly unsafe. If a machine gets contact with rain on any of the 6 sides of the block, it can catch fire. If a machine gets lit on fire, it can explode. If a wire exceeds its current rating, it will catch on fire.

When using battery buffers, be sure to watch the output and input amps. Be careful when distributing power from one battery buff to another battery buff further away. The destination battery buff will pull 2A per battery. If the source battery buff has more batteries than the power cable can handle, the cable will catch fire. One way to prevent excessive current from a battery buffer output is to limit the number of batteries in the buffer to the amperage of the cable. 1 batt can output 1A. If you need to store more power, you place a large, x16 battery buff next to smaller battery buff, such as a x4, that is connected to your distribution cable. This will let you store 20 batts of power and safely output 4A of power. You can expand power storage by placing additional x16 batt buffs against the x4. Just remember, if you need to place a wire between them, it needs to be at least an 8 A wire!

Energy conversions
GregTech energy and IC2 energy are not the same. So GregTech energy systems cannot automatically use IC2 energy, and thus need to be converted, and vise versa.

To convert IC2 EU into GT EU, connect (directly adjacent) a GT Transformer's input face to an IC2 Energy Source's output face. This means connecting the output dot of a IC2 transformer/storage block to the input dot of a GT Transformer.

To convert GT EU into IC2 EU, connect GT cables to IC2 blocks

Energy storage management
More advanced GregTech power options such as nuclear reactors or large turbines run constantly whether or not the EU they are generating is being used. It can be advantageous to create a system that turns the power generation on when your battery is empty, and turns it off when your battery is full. This is particularly important for things like boilers and turbines that have a low-efficiency "warm up" time that needs to be minimized. A compact latch system that can be set up in the LV era is shown to the right. Two energy detector covers are attached to a batter buffer, one on either side. Both are in 'Normal Electrical Storage (including batteries)' mode, though the one on the left is inverted. The mode of the covers can be toggled using a screwdriver.

The energy detector cover on the right sends a max strength signal when the battery is full; the one on the left sends a max strength signal when it is empty. In the compact latch system, the wire on the right (shown as on in the image) comes from the non-inverted energy detector cover. It connects to a vanilla redstone comparator, and then into a RS latch. The wire on the left comes from the inverted energy detector cover, and also connects to a separate comparator and into the other side of the RS latch. In between the redstone comparators is a potentiometer (set to level 14) that tells the system only to pass the redstone signal through to the latch if it is near maximum strength.

In this example the latch sends out the resulting redstone signal to a wireless transmitter, though conventional redstone wires can also be used. The redstone signal sent by the latch must be connected to a machine control cover to control large turbines, or can be directly connected to an IC2 nuclear reactor.

Even more compact systems are possible by utilizing dense red crystals instead of potentiometers and comparators, though this requires some investment in magical research.

Snagger's Electricity Guide for New Players
This section contains information that I wish I had known when I started playing. Much of it has been discovered by asking for help in the discord. If you still have further questions, remember you can get your questions answered instantly on the Discord:https://discord.gg/EXshrPV. at all hours of the day. Many thanks to moronwmachinegun, codewarrior0, Bluebine, Bryfer, and others for their impressive and vast amounts of knowledge that helped make this write-up possible :).

GregTech's electricity mechanics involve 5 concepts you should understand:
 * 1) Voltage (V)
 * 2) Energy Unit (EU) and Ticks (EU/t)
 * 3) Amperage (A)
 * 4) Internal Energy Buffers
 * 5) EU Cable Loss

We'll assume for the this TL;DR (lol) that we're only using the Low Voltage (LV) tier, which has a maximum voltage of 32V. When you look at a recipe for a machine (by clicking on the progress bar in the middle, or by hovering over an ore in NEI and pressing "u"), you'll see the details listed below. For this example we'll look at the Crushed Iron Ore recipe used in the Basic Ore Washing Machine:



Total: 8000 EU Usage: 16 EU/t Voltage: 16 EU Amperage: 1 Time: 25.00 secs

1. Voltage (V)
Voltage is not a finite resource that is used up or stored, but rather a constant value used to determine the tier of electricity/generators/machines. Power generators create power and machines use them. There are 9 tiers of electricity/generators/machines. The voltage a machine receives must be less than or equal to the maximum voltage it can handle. For example, an MV machine has a maximum voltage of 128V, so it can accept power up to 128V, and run any recipes that require 128V or less. If you try to run a recipe that requires more than 128V, it won't run, and if you give it more than 128V, it will catch fire or explode.

The voltage listed in the recipe is the MINIMUM required voltage the machine needs to run this recipe. Since our Basic Ore Washing Machine is in the LV tier and can use a maximum of up to 32V, the recipe for Crushed Iron Ore will run in the machine as long as we supply it with between 16V and 32V. If supplied with less than 16V (ULV provides 8V), the machine won't run, and if supplied with more than 32V, the machine will explode.

2. Energy Unit (EU)
In contrast to Voltage, EU is a finite resource that can be stored, transferred, and used up much like a liquid. You can see in our Ore Washing Machine example that this recipe requires 8000 EU to complete. A tick is the shortest segment of time that we use in Minecraft for all practical purposes, and is equal to 1/20 of 1 second. The usage of the recipe is 16 EU/t, so 8000 EU at a rate of 16 EU/t would require 500 ticks to complete (8000/16=500). 500 ticks is equal to 25 seconds (500/20=25), which you can see matches the time shown in the recipe details.

3. Amperage (A)
Amperage (or amps) can be thought of as packets that contain EU. All generators produce 1 amp per tick. The Voltage and the EU contained in this amp is determined by the generator's tier. For example, an LV generator (let's say a Basic Steam Turbine) generates 1 amp of 32V power every tick. This amp contains 32 EU. In other words, the Basic Steam Turbine produces 32 EU/t.

4. Internal Energy Buffers
Looking again at our Basic Ore Washer example, a hidden piece of information that can only be displayed once you're able to build a scanner is its internal buffer of EU. All machines have a buffer in them that they draw power from and use to run their recipe. This internal buffer is then replaced and filled back up with EU produced by the generator. The internal buffer for LV machines is 2048 EU.

Amps cannot be split into smaller pieces. Disregarding cable loss (we'll get there next), a 32V amp will always deliver 32 EU. So when a generator connected to a few machines broadcasts "I have an amp I can send out!", the machines will check their internal buffer to see if they have room for 32 EU. If it has empty space in its buffer, it will respond with "Yes, I have space in my buffer for that amp, give it here!", the amp will be sent, and 32 EU will be added to the machine's internal buffer. Note again that a generator can only produce 1 amp per tick, so if 2 machines respond to the "amp push" of the generator, only 1 can receive the amp, and the other will have to wait until the next tick to receive its desired amp.

Looking at our Basic Ore Washer example (and disregarding cable loss for now), let's use this chart to track the internal buffer tick by tick:

So when running this recipe, the LV Ore Washer only requests an amp every other turn. So you could run 2 ore washers side by side from a generator that produces 1 amp/tick. An LV Macerator running a recipe that uses 2 EU/t would only request an amp every 16 ticks. You could run 16 macerators simultaneously from a single generator.

Let's look at one more example. This time, let's look at the recipe for Purified Iron Ore in the Basic Thermal Centrifuge:



This one is interesting because even though the voltage is 24 EU (LV tier), it requires 48 EU/t. It will require the use of 2 amps. For simplicity's sake, let's assume there's no cable loss this time.

You can see how this recipe will alternate between using 1 amp and 2 amps every tick. 2 generators would provide enough amperage for 3 LV Thermal Centrifuges to run 48 EU/t recipes simultaneously.

One final thing to note is, and this is somewhat confusing, the machine can accept the amperage displayed + 1 amps every tick. So machines can technically accept different quantities of amps per tick depending on which recipe is being run.

5. EU Cable Loss
Cables are what connect generators to machines, and most cables have something called cable loss. Different cables have different loss amounts, but the idea is that a packet (aka amp) will lose some of the EU it contains for every block it has to travel through. For example, a 1x Tin Cable has a max voltage of 32, a max amperage of 1, and a loss/meter/amp of 1 EU. The amp will lose 1 EU for every block it travels, so if it has to travel 4 blocks from the generator to the machine, it will arrive and only have 28 EU to deliver.

Let's use our Basic Ore Washer example once again to look at 2 examples with different distances between machine and generator to see how this works in practice. Let's assume in the first example the machine is 16 blocks away from the generator and is connected to 2 generators with a 2x Tin Wire with 1 EU/meter/amp cable loss (so that we'll be able to accept 2 amps in a single tick when necessary). We'll use this chart to track the internal buffer tick by tick:

Distance away from generator: 16 blocks

You can see how the buffer would continue to be filled every tick with 16 EU. Pretty simple example. Now for another one with more distance:

Distance away from generator: 24 blocks

Here, there is so much cable loss that after the first 5 ticks of operating, the machine would start requesting 2 amps each tick, and each amp would only end up delivering 8 EU each for a combined total of 16 EU/tick.

Note that the machine is not aware of the cable loss that will occur once the packet arrives, so it requests the amp when it has room for the size of the full packet it THINKS it's going to get, not when it has room for the EU the packet will ACTUALLY contain after cable loss.

6. Useful (and not always obvious) Information
$$\frac {2 \cdot U_{Recipe} } {T} + 1$$
 * Machines require electricity based on the recipe that's being run, not the tier of the machine or anything else.
 * Machines have an internal buffer and the machine draws power from this buffer, not directly from a generator.
 * 4 AMPS CAN POWER MORE THAN 4 MACHINES SIMULTANEOUSLY. I still see veteran GT players do this all the time: they use a transformer to step down the voltage and then run a 4x cable to 4 machines. Unless you're planning on having those 4 machines all run max EU/t recipes constantly, you're providing WAY too much amperage.  Those 4 amps can mostly like supply enough simultaneous amperage and EU/t for 8-12 machines, depending on the machines and recipes of course.
 * The buffer is always refilled by a whole amp and cannot be split into anything smaller.
 * Generators always try to give out their max EU. So the first generator along a wire will drain all its EU first before the second one, etc. Order is determined by how Minecraft processes tile entities, and will change on chunk reloading.
 * Machines in a network will always get their EU from the same generator in the same order. A second generator in a second location must traverse the wire differently. The order in which direction the wire provides power is the same. This means that a generator does not provide power to the closest machine first! Each wire pushes power out in the same order, probably this D-U-N-S-W-E.
 * It's a push system, meaning machines don't request amps, but rather generators push amps out along their cable network.
 * Machines can request 1 additional amp than their recipe requires, if they have room in their buffer. The exact formula for how many amps a machine can use is:

So at LV, recipes with 0-15 EU/t accept 1 amp, 16-31 EU/t accept 2 amps, recipes with 32-47 EU/t accept 3 amps, and so on. This is why machines only charge at 1A when no recipe is active.

Trivia
Since version 5.0 (for Minecraft 1.7.2) GregTech has its own Energy System since GregoriusT wasn't satisfied with IC2 Experimental's Energy System.