Low voltage systems tend to be ungrounded; nevertheless, if the supply system is grounded, non-current-carrying metal portions of equipment linked with low voltage systems are needed to be grounded.
It is vital to understand the requirements for grounding low voltage systems under NEC regulations before grounding your low-voltage systems.
It is also vital to understand the difference between system and equipment grounding. One conductor from a supply system is purposely connected to the ground to connect to the earth. The other conductors supplied by the system establish a reference to earth.
When equipment is grounded, it is connected to the ground or to a conductive body that extends the connection. Equipment grounding is the process of placing equipment at or near the same potential (voltage) as the earth. The equipment grounding conductor, or another grounding conductor sizing, is a conductive body that extends the ground connection.
It would help if you were sure, you have the right NEC ground wire size no matter what you are grounding. To help here, in our guide, there is more information regarding grounding wire size, and for ease of reference, we have a grounding wire size chart.
By the end, you can quickly check the ground size chart and ensure your conductor size is sufficient as it won’t cause damage to any overcurrent device that trips your circuit breaker. (Read Light Bulb Socket Sizes Chart)
What Size of Ground Wire Is Needed?
The ground wire is copper in most homes and is #6 (6 AWG) or larger. Therefore, a #4 grounded electrode conductor is required for the 200-amp service.
The following definitions are found in Article 100 of the NEC 2008:
- The equipment grounding conductor is a conductive path used to connect specific non-current-carrying metal parts of your equipment to the system grounded conductor or your grounding electrode conductor.
- A grounded conductor is a system or a circuit conductor you have intentionally grounded.
- Grounding Electrode Conductor is a conductor that connects a grounding electrode or a point on the grounding electrode system to the system grounded conductor or equipment.
- Grounding Electrode will be a conducting object where a direct connection to earth is made.
The Code goes into great length about grounding because it is such a vital topic that, if done incorrectly, can cause problems in both low and high-voltage circuits.
Here you can see the NEC grounding recommendations for low-voltage systems. Again, 50 volts will be the threshold because that’s the level used in the Code.
Section 250.20 of NEC contains regulations on grounding systems at less than 50 volts (A) and the three conditions you need to meet for systems.
- When supplied by a transformer with a primary voltage higher than 150 volts, systems with less than 50 volts must be grounded.
- If the primary side of the transformer is not grounded, systems with less than 50 volts must be grounded when a transformer feeds them.
- Systems with less than 50 volts must also be grounded if feed conductors run outside as overhead conductors.
The NEC additionally specifies which low-voltage systems are not to be grounded. For example, low-voltage lighting systems are covered, as are transformer-supplied secondary circuits for these lighting systems. Low voltage landscape lighting systems and others are examples.
What is the definition of a grounded system? In a grounded system, one conductor is purposely grounded. No intentionally grounded conductor is supplied by the system that you connect or ground to earth).
The definitions of the terms ground, grounded, or grounding are:
“Ground. The earth.”
Being grounded (Grounding) is something connected to the ground directly or using a conductive body extending the ground connection.
Certain sections of the NEC provide grounding criteria for specific fixed equipment. Regardless of the voltage, the listed equipment must be grounded or linked to an equipment grounding conductor.
To put it another way, if the equipment, such as conduits, boxes, and devices, is placed for an ungrounded system, the equipment grounding criteria do not apply. (Read Allen Wrench Sizes Chart)
All the associated equipment must be grounded if the supply system is grounded. Conduit sleeves and back boxes used within interior walls for a communications circuit or a fire alarm circuit fed from a power supply with an ungrounded secondary illustrate this in typical applications.
|Rating or Setting of Automatic Overcurrent Device in Circuit Ahead of Equipment, Conduit, etc. Not Exceeding (Amperes)||Copper (AWG or kcmil)||Aluminum (AWG or kcmil)|
Does Ground Wire Need To Be Same Size?
The earth must be about the same diameter as circuit conductors for house wiring. However, motors or heating equipment frequently employ one smaller diameter in manufacturing. This is because grounding may trip the circuit breaker or fuse if the wire is hot.
NEC Table 250.66 is used for sizing grounding electrode conductors for alternating current systems. An article called Grounding Electrode Conductor tells you how this piece of equipment is connected to a grounding electrode.
In prior editions of the NEC, the largest ungrounded service-entrance conductors were utilized to determine how prominent the grounding electrode conductor should be on alternating current systems.
In the 2020 NEC, the word “service-entrance” was omitted from the table since this table is also used to determine grounding electrode conductor size for buildings or structures supplied by feeders or branch circuits or at a separately derived system of a grounded or ungrounded AC system.
The grounding electrode conductor is not intended to carry current under normal conditions. Still, it provides a path to the grounding electrode to decrease voltage generated by lightning, power line surges, or unintended contact with higher-voltage lines.
As a result, the grounding electrode conductor is not the same size as conductors that are meant to carry current all the time.
When using the table, the size of a grounding electrode conductor depends on the size of the most prominent ungrounded conductor on alternating current systems.
For a service, occasionally, the utility company installs the service entrance conductors after the electrician is finished. Therefore, the electrician has no notion what size service entrance conductors will be installed until then. (Read 150 Amp Wire Size Guide)
Table 250.66 clarifies that if no service-entrance conductors are present, “the grounding electrode conductor size shall be determined by the equivalent size of the largest service-entrance conductor size necessary for the load to be served.”
Some grounding electrodes are not sized from Table 250.66. Under certain situations, ground rods, ground pipes, ground plates, concrete encased electrodes, and ground rings may be permitted to be smaller than the values in Table 250.66 according to Section 250.66(A) through (C).
Underground water pipe electrodes and metal in-ground support structures covered in 250.52 are consistently sized from Table 250.66.
What Size Ground Wire Do I Need For A 50 Amp Circuit?
Such a circuit would need 6 wwg conductors and ground of 10 w g as a minimum.
Equipment grounding conductors made of copper, aluminum, or copper-clad aluminum of the wire type must not be smaller than those listed in Table E3908.12. Still, they are not required to be larger than the circuit conductors that supply the equipment.
Section E3908.4 applies when a grounding raceway, cable armor, or sheath is used as the equipment grounding conductor, as specified in Section E3908.8.
When ungrounded conductors are extended beyond the smallest size that provides sufficient amp capacity for the intended installation, wire-type equipment grounding conductor sizing must be increased correspondingly to the largest ungrounded conductor circular mil area. (Learn How To Disconnect Hard Wired Smoke Alarm)
Here you can find tables that give the setting of automatic overcurrent device in AWG or kcmil.
|Size Of Largest Ungrounded|
Or Equivalent Area For Parallel
|Size Of Grounding|
|2 or smaller||1/0 or smaller||8||6|
|1 or 1/0||2/0 or 3/0||6||4|
|2/0 or 3/0||4/0 or 250||4||2|
When a single equipment grounding conductor is used to connect multiple circuits in the same raceway or cable, it must be sized to protect the raceway or cable’s largest overcurrent device voltage drop.
What Size Ground Wire Is Required For A 200 Amp Service?
The minimum size of grounding conductors for 200 amp circuit protection should only be #6 copper or (4) aluminum, according to NEC Article 250. If you’re in the United States, you’ll probably stick to the National Electrical Code (NEC).
National Electrical Code – NEC 2008
- Main, Bonding Jumper is a connection between a grounded circuit conductor and the equipment grounding conductor at the service.
- Conductor for Grounding. A conductor is used to connect equipment or a wiring system’s grounded circuit to a grounding electrode or grounding electrodes.
- Equipment, Grounding Conductor (EGC). The conductive path between non–current carrying metal portions of equipment and the system grounded conductor, grounding electrode conductor, or both.
- Electrode for grounding. A conducting object that establishes a direct connection to the earth.
- Electrode Conductor for Grounding. A conductor connects a grounding electrode or a point on the grounding electrode conductors or to the system grounded conductor or equipment.
The size of the Main Bonding Jumper, Grounding Electrode Conductor, and Grounded Electrode is defined by table 250.66
Continuity and Attachment of Equipment Grounding Conductors to Boxes
If you look at the 200-ampere row, the 225-ampere rating row is more significant than the 300-ampere row. This is because the EGC must be 4 AWG for copper wire, and for aluminum or copper-clad copper, it must be 2 AWG.
Follow the same steps to determine what size conductor you need for any installation supply side. The minimum set out in the table isn’t enough for some installations.
The note below Table 250.122 says where it is necessary to meet requirements; the equipment grounding conductor shall be larger than given in this table, (250.122) which means the conductor should be sized larger.
Notes that are part of the NEC National Electrical code tables must be there (unlike Informational Notes). The reasoning for such notes is a high fault current on the supply side can damage or melt the equipment grounding conductor.
According to Section 250.122(B), wire-type equipment grounding lines must be sized larger in proportion to the circular mil area of ungrounded conductors.
This means that “if ungrounded conductors are increased in size for any reason other than as required in 310.15 (B) and 310.15 (C), wire-type equipment grounding lines must be made larger in proportion to the circular mil area.”
When there is a long branch circuit or feeder, the ungrounded conductors might get more significant to make up for voltage drop. (Read Can You Use A Junction Box To Extend Wiring)
Therefore, unless correction or adjustment factors are used, if a feeder or branch-circuit conductor is increased in size, the wire-type grounding conductor for this circuit would have to be increased at least as much as the feeder or circuit conductor size is increased.
There will be a 200-ampere rating feeder that goes through the middle of an extensive building. If the voltage dropped too much, this feeder would not work.
Table 310.16 says a 3/0 AWG copper conductor is needed for a 200-ampere rating. Instead, a 250-kcmil copper conductor was chosen for this job.
Table 250.122 usually says that the grounding conductor size for the 200-ampere rating of the automatic overcurrent device should be 6 AWG copper.
In size, to figure out how big an equipment grounding conductor size we need for this feeder, we would need to use the formula shown.
When the conductor size isn’t given in circular mils, we’ll need to use Table 8 of NEC Chapter 9 to figure out the area in circular mils (AWG).
Ground wires for residences typically are made of copper and are #6 (6 AWG) or larger. For 200 Amp services, a #4 grounding electrode conductor (ground wire) is required.What size ground wire for 200 amp equipment? ›
The minimum size equipment grounding conductor for this 200-ampere feeder is a 4 AWG copper conductor.What size ground wire do I need for 100 amp service? ›
The ground wire size for 100 Amp service is different. You would typically use 8 AWG copper grounding wire or 6 AWG aluminum grounding wire.What happens if ground wire is too big? ›
Using too large a wire gauge, with a higher rated amperage than the circuit breaker, can lead to a tripped circuit even if the load doesn't exceed the wire's rating.Can a ground wire be too small? ›
With too-small a ground wire, the breaker cannot magnetic-trip because it cannot flow enough current to hit 10x, because of the too-high resistance of the wire. And as you can guess, that's trouble.What size ground for 250 amps? ›
As an example, a service consisting of a 250 kcmil copper conductor per phase would demand a minimum sized grounded conductor for this service of 2 AWG copper or 1/0 AWG aluminum or copper-clad aluminum conductors.What size ground for 400 amps? ›
Size of the cables to use for a 400 Amp Meter Base
These sizes are relevant both for single-phase and three-phase service. As for the grounding conductors, the minimum size is 3 AWG for copper or 1 AWG for aluminum or aluminum copper-clad. This is the minimal size of the grounding conductor, as per NEC 2020.
The grounding conductor must be a minimum of #4 copper for a 200 ampere service.Can I use a 8 gauge ground wire on a 50 amp circuit? ›
No, 8 AWG wire cannot carry 50 amps safely. 50 Amps requires at least 6 AWG wire.Does gauge matter for ground wire? ›
If enough ground fault current flows, the circuit breaker will trip. Even without AFCI breakers, the 16-gauge ground wire should be adequate in most instances to clear a short, a fault, or an overload.
According to Table 250.122, the circuit equipment grounding conductor for a 40A overcurrent device will be 10 AWG (10,380 circular mil), but the circuit equipment grounding conductor for this circuit must be increased in size by a multiplier of 1.59. Thus, you must use an 8 AWG grounding conductor (Chapter 9, Table 8).What size ground do I need for a 1000 amp service? ›
|Rating or Setting of Automatic Overcurrent Device in Circuit Ahead of Equipment, Conduit, etc., Not Exceeding (Amperes)||Size (AWG or kcmil)|
|Copper||Aluminum or Copper-Clad Aluminum*|
The recommended way to ground your amplifiers is to keep your ground cable less than 18" long, the same exact size/gauge as the power cable, bolted directly to a solid, thick steel part of the chassis which is scraped and polished clean of any paint or primer for best possible grounding.What size ground for 50 amps? ›
Your conductors need to be 6awg and your ground needs to be 10awg per nec code for a 50a circuit.What is the maximum grounding wire size? ›
A grounding electrode conductor (GEC) from an electrical service to a ground rod, pipe or plate type electrode is never required to be larger than 6 AWG copper or 4 AWG aluminum unless the GEC continues on from the rod, pipe or plate to connect another electrode that may require a larger GEC such as a concrete encased ...Is it OK to splice a ground wire? ›
Splicing is permitted by irreversible compression-type connectors listed for grounding or by exothermic welding. Sections of busbars can be connected together to form a grounding electrode conductor.Which ground wire should not be smaller than number? ›
The cross section of earth continuity conductor or loop earth wire should not be less than 2.9 mm2 (14 SWG) or half of the size of the sub circuit or half of the installation conductor size.Can ground wire be 14 gauge? ›
Covers 2000 ft. (18¢ /ft.)Is it OK for ground wire to touch other wires? ›
Never have the ground wire touching an exposed hot or neutral wire or it will give the current an alternative path to travel, which could cause problems with the device being powered.Does ground wire need to be sized for voltage drop? ›
Section 250.122(B) requires that if the ungrounded conductors are increased in size for voltage drop, the EGC needs to be increased in size too, proportionately.
Can a ground wire be smaller than a power wire? The ground wire can always be one wire size smaller than the main & neutral conductors. There is also locations & applications that the ground can be much smaller, consult the national electrical code for specifics.What size ground wire for a 500 watt amp? ›
A basic rule of thumb is this. For up to 500 watts RMS, 8 gauge is sufficient. In the 500 – 1000 watt RMS range, you want to run 4 gauge.What size ground for 320 amps? ›
#4 SDC Ground Wire (200 amp). 6. #0 SDC Ground Wire (320 amp).What size ground for 800 amp equipment? ›
This means if the overcurrent protective device for a feeder is rated at 800 amperes, the size of equipment grounding conductor (wire-type) cannot be less than 1/0 copper or 3/0 kcmil aluminum or copper-clad aluminum.What is the best ground wire for an amp? ›
The best way to ground your car stereo components is to run a 10 or 12-gauge wire from the amp, and 12-gauge from all other components, such as head unit and active crossovers, to a central location. Then run a single ground to the best source of ground, the negative terminal on your car's battery.Can I use the same ground for 2 amps? ›
In a mirror image of the power distribution block, you should connect the individual amps to the ground distribution block, which should be connected to a good chassis ground. You can use the same ground block for your other audio components, which is also a good way to avoid ground loop issues.What is the voltage to ground of a 480 volt 3 phase 3 wire system? ›
The voltage to ground for ungrounded circuits is the greatest voltage between the given conductor and any other conductor of the circuit. For a 3-phase, 3-wire ungrounded 480-volt system the voltage to ground is 480-volts.What is the voltage to ground for 3 phase 480? ›
The voltage between any one leg and ground will be 277 volts, and between any 2 hot wires will be 480 volts. 3 phase machinery runs off Delta voltage, which means you only run 3 hot wires and no neutral wire.What size ground for 150 amps? ›
A 150 amp service would normally be size 1 copper and size 2/0 aluminum. That would mean the grounding electrode conductor would need to be at lease size 6.How many amps is a #8 ground good for? ›
#8 Gauge THHN Copper Stranded Wire is the most popular single conductor copper wire we carry and is RATED FOR 55 AMPS @ 90°C.
6 AWG Wire Used For 50 Amp Service.What is the max amp for #8 wire? ›
|NM, TW, & UF WIRE (Copper Conductor)||SE CABLE (Copper Conductor)|
|12 AWG - 20 AMPS||6 AWG - 65 AMPS|
|10 AWG - 30 AMPS||4 AWG - 85 AMPS|
|8 AWG - 40 AMPS||2 AWG - 115 AMPS|
|6 AWG - 55 AMPS||1 AWG - 130 AMPS|
Copper grounding wire is commonly used in electrical applications, particularly because of its conductivity and durability. There are many different types of copper wires that are used, depending on the application requirements. The most common types of grounding wires include bare copper and gauged copper wire.Can I use any wire for ground? ›
Contractors can use both bare and insulated wire for grounding purposes.What happens if you use too small gauge wire? ›
If too small a wire is used (high AWG), then the wire may overheat, melt or catch fire. Therefore, it is important that the current carrying capacity of a wire or circuit be considered. Larger wire uses more metal and is, therefore, more expensive.Can 8 gauge wire handle 40 amps? ›
8 gauge wire is rated for 40 amps, and it can safely handle up to 50 amps. This 40 amp wire size can safely handle most needs.What size ground for 70 amps? ›
If you really want 70A, then again THWN in conduit gives you an advantage as this only requires #6 copper or #4 aluminum conductors and a #8 ground.How many amps is a 12 ground good for? ›
RULES OF THUMB
“Twelve-gauge wire is good for 20 amps, 10-gauge wire is good for 30 amps, 8-gauge is good for 40 amps, and 6-gauge is good for 55 amps,” and “The circuit breaker or fuse is always sized to protect the conductor [wire].”
#10 Gauge THHN Copper Stranded Wire is the most popular single conductor copper wire and RATED FOR 30 AMPS.What size ground wire for a 60 amp subpanel? ›
20 amp: 12 gauge (yellow) 15 amp: 14 gauge (white) 15-60 amp: 6 gauge. 40-50 amp: 8 gauge.
Though it is common practice to share two circuits with one ground, but whether you should do so depends on your local NEC regulations. The electrician you will hire knows the rules to follow.Can a ground cable be too long? ›
4. Ground wire too long: If your ground wire is too long, it can act as an antenna and pick up unwanted noise. To troubleshoot this issue, try shortening the length of your ground wire or using a shielded cable.Do amps sound better off the ground? ›
The amp will disperse its sound into the room better if it is raised up.Will an amp work without a ground? ›
In the case of amplifiers, this is the audio signal, which is an AC that has frequencies between 20 Hz and 20,000 Hz (or more). It also acts are a reference point for power supply voltages and the like. A clean signal ground is required for audio devices so as not to induce noise into the signal.
50 AMP Wire Size
For a maximum of 50 amps, you'll need a wire gauge of 6. Fifty amp breakers are most often used to power many different appliances. However, a kitchen oven can alone require 50 amps. Many electric dryers also require a 50 amp breaker.
|Size Of Copper Wire (AWG or kcmil):||Copper Grounding Electrode Conductor Size (AWG or kcmil):||Amps:|
|6 AWG Copper Wire||8 AWG Copper Ground Wire||65 Amps|
|4 AWG Copper Wire||8 AWG Copper Ground Wire||85 Amps|
|3 AWG Copper Wire||8 AWG Copper Ground Wire||100 Amps|
The optimal wire sizes for a 60 Amp circuit breaker are 4 AWG copper or 3 AWG aluminum. The ampacity of the 4 AWG copper wire is 85 amps at 75°C. The ampacity of the 3 AWG aluminum wire is 75 amps at 75°C.Can I use 14 gauge ground with 12 gauge wire? ›
As long as there are both 12 gauge and 14 gauge grounds going back to the (same) electrical panel, that will be fine.Does the ground wire need to be the same size as the power wire? ›
Can a ground wire be smaller than a power wire? The ground wire can always be one wire size smaller than the main & neutral conductors. There is also locations & applications that the ground can be much smaller, consult the national electrical code for specifics.Can I use 14 gauge ground wire on 20 amp circuit? ›
NO! You cannot use any 14 gauge wire on a 20 amp circuit. This is true, even running to a light fixture that has smaller wires built in. The wires built into the fixture are allowed as part of a manufactured assembly.
Copper grounding wire is commonly used in electrical applications, particularly because of its conductivity and durability. There are many different types of copper wires that are used, depending on the application requirements. The most common types of grounding wires include bare copper and gauged copper wire.Can I use 10 gauge wire for ground? ›
Q:What is the appropriate wire to use to ground an outdoor tv antenna? A: THE MINIMUM SIZE WIRE YOU SHOULD USE TO CONNECT THE ANTENNA TO THE HOUSE SERVICE GROUND IS 10 AWG.Can I use 14 gauge ground wire on 15 amp circuit? ›
14-gauge wire is safe to use when wiring an outlet on a 15 amp or lower circuit. Never use 14-gauge wire for an outlet on a circuit over 15 amps. Check your breaker box to find out the amperage of the circuit your outlet is on. 14-gauge wire is cheaper than 12-gauge wire.Does ground wire need to be thicker? ›
The current is equal at all points in a series circuit (Kirchoff's current law). The same amount of current therefore flows through the positive and ground wires. Both wires need to be at least thick enough to handle the current the circuit draws, but they can have different thicknesses.What is the minimum size ground for a 20 amp circuit? ›
|RATING OR SETTING OF AUTOMATIC OVERCURRENT DEVICE IN CIRCUIT AHEAD OF EQUIPMENT, CONDUIT, ETC., NOT EXCEEDING THE FOLLOWING RATINGS (amperes)||MINIMUM SIZE|
Grounding wires serve as an alternate path for the current to flow back to the source, rather than go through anyone touching a dangerous appliance or electrical box. Confusion arises because it is commonly referred to as a ground wire even though it is more correctly called a "grounding" wire.Is solid or stranded wire better for grounding? ›
In general, solid cables are better electrical conductors and provide superior, stable electrical characteristics over a wider range of frequencies. They're also considered more rugged and less likely to be affected by vibration or susceptible to corrosion, since they have less surface area than stranded conductors.