What Size Copper Ground Wire For 400 Amp Service

For every wire, y'all will need a ground wire. As you may know, the ground wire doesn't have to be as big as the principal wire. Example: 1 AWG copper wire doesn't crave a 1 AWG copper ground wire. Information technology requires a 6 AWG copper basis wire. A basis wire size nautical chart that follows will tell you exactly the size of the grounding conductor you need.

Now, it's important to empathize that you cannot go wrong with a bigger-than-required ground wire. A big basis wire is just an overkill that will cost you more. That's it.

what size ground wire do i need — With smaller wires (8 AWG or smaller), you can utilize the aforementioned size ground wire as the main (hot) wire.

To notice the most optimum ground wire size, you take to consult the 'NEC Grounding Conduction Size Chart'.

What section of the NEC covers grounding?

National Electrical Code (NEC) covers the sizes of ground wires in Commodity 250, Table 250.66 titled 'Grounding Electrode Usher For Alternativing Current Systems'.

Since it'due south not all that easy to get hands on these new 2020 NEC guidelines, we are sharing this chart below. You volition see two charts:

1st chart covers the size of copper wires (from eight AWG to 2000 kcmil) and their corresponding copper ground wires.
second chart covers the size of aluminum wires (from six AWG to 2000 kcmil) and their corresponding aluminum ground wires.

To figure out what size ground wire you lot need, just consult these two charts. Below each chart, nosotros also list some examples of footing wire sizing choices:

Copper Basis Wire Size Chart (Copper Grounding Conductor Size Chart)

Size Of Copper Wire (AWG or kcmil):	Copper Grounding Electrode Usher Size (AWG or kcmil)
8 AWG Copper Wire	viii AWG Copper Ground Wire
vi AWG Copper Wire	viii AWG Copper Ground Wire
4 AWG Copper Wire	viii AWG Copper Basis Wire
iii AWG Copper Wire	viii AWG Copper Ground Wire
two AWG Copper Wire	8 AWG Copper Ground Wire
1 AWG Copper Wire	6 AWG Copper Ground Wire
0 (1/0) AWG Copper Wire	half dozen AWG Copper Basis Wire
00 (2/0) AWG Copper Wire	four AWG Copper Ground Wire
000 (3/0) AWG Copper Wire	4 AWG Copper Ground Wire
0000 (four/0) AWG Copper Wire	2 AWG Copper Ground Wire
250 kcmil Copper Wire	2 AWG Copper Footing Wire
300 kcmil Copper Wire	2 AWG Copper Ground Wire
350 kcmil Copper Wire	2 AWG Copper Basis Wire
400 kcmil Copper Wire	0 (1/0) AWG Copper Footing Wire
500 kcmil Copper Wire	0 (i/0) AWG Copper Ground Wire
600 kcmil Copper Wire	0 (1/0) AWG Copper Ground Wire
700 kcmil Copper Wire	00 (2/0) AWG Copper Ground Wire
750 kcmil Copper Wire	00 (2/0) AWG Copper Ground Wire
800 kcmil Copper Wire	00 (ii/0) AWG Copper Basis Wire
900 kcmil Copper Wire	00 (2/0) AWG Copper Basis Wire
1000 kcmil Copper Wire	00 (two/0) AWG Copper Footing Wire
1250 kcmil Copper Wire	000 (3/0) AWG Copper Ground Wire
1500 kcmil Copper Wire	000 (3/0) AWG Copper Ground Wire
1750 kcmil Copper Wire	000 (3/0) AWG Copper Basis Wire
2000 kcmil Copper Wire	000 (three/0) AWG Copper Ground Wire

Let's expect at two examples:

What size footing wire practice I demand for a 3 AWG wire?

3 AWG wire has an ampacity of 100A at a median 75°C (167°C) temperature. This is likewise why people confuse information technology with beingness a 100 amp wire. Y'all can check what size wire you demand for 100 amps hither.

To effigy out the size of ground wire, you consult the copper grounding usher size chart, and you see that y'all need an 8 AWG copper footing wire for 3 AWG copper wire. Now, there is nothing wrong if you use a 6 AWG or even 4 AWG footing wire; it will do the same task, it will merely cost more.

What size basis wire do I demand for 250 kcmil wire?

250 kcmil copper wire has a 255A ampacity at a median usher temperature. If you lot use the NEC fourscore% rule, 250 kcmil wire can handle upwards to 204 amps. That'southward why it is considered a 200 amp wire. Basically, we are trying to answer what ground wire do y'all need for 200 amp service.

If you consult the copper ground wire size chart above, you lot can encounter that you volition need a two AWG copper ground wire to fairly ground a 250 kcmil wire. Basically, you lot need a 2 AWG copper ground wire for a 200 amp service.

Let'southward look at the NEC recommendations for aluminum wires also:

Aluminum Ground Wire Size Chart (Aluminum Grounding Usher Size Chart)

Size Of Aluminum Wire (AWG or kcmil):	Aluminum Grounding Electrode Conductor Size (AWG or kcmil)
6 AWG Aluminum Wire	6 AWG Aluminum Ground Wire
4 AWG Aluminum Wire	6 AWG Aluminum Footing Wire
3 AWG Aluminum Wire	half dozen AWG Aluminum Footing Wire
2 AWG Aluminum Wire	six AWG Aluminum Ground Wire
one AWG Aluminum Wire	4 AWG Aluminum Ground Wire
0 (i/0) AWG Aluminum Wire	4 AWG Aluminum Basis Wire
00 (two/0) AWG Aluminum Wire	2 AWG Aluminum Ground Wire
000 (iii/0) AWG Aluminum Wire	two AWG Aluminum Footing Wire
0000 (4/0) AWG Aluminum Wire	0 (i/0) AWG Aluminum Basis Wire
250 kcmil Aluminum Wire	0 (ane/0) AWG Aluminum Ground Wire
300 kcmil Aluminum Wire	0 (1/0) AWG Aluminum Ground Wire
350 kcmil Aluminum Wire	0 (1/0) AWG Aluminum Ground Wire
400 kcmil Aluminum Wire	000 (three/0) AWG Aluminum Ground Wire
500 kcmil Aluminum Wire	000 (3/0) AWG Aluminum Footing Wire
600 kcmil Aluminum Wire	000 (3/0) AWG Aluminum Ground Wire
700 kcmil Aluminum Wire	0000 (4/0) AWG Aluminum Ground Wire
750 kcmil Aluminum Wire	0000 (four/0) AWG Aluminum Ground Wire
800 kcmil Aluminum Wire	0000 (4/0) AWG Aluminum Ground Wire
900 kcmil Aluminum Wire	0000 (4/0) AWG Aluminum Ground Wire
1000 kcmil Aluminum Wire	0000 (4/0) AWG Aluminum Ground Wire
1250 kcmil Aluminum Wire	250 kcmil Aluminum Footing Wire
1500 kcmil Aluminum Wire	250 kcmil Aluminum Ground Wire
1750 kcmil Aluminum Wire	250 kcmil Aluminum Ground Wire
2000 kcmil Aluminum Wire	250 kcmil Aluminum Ground Wire

Compared to copper wires, aluminum wires take about 39% lower conductivity. That's why you accept to use different grounding wires for aluminum wires.

Let's look at 2 examples of aluminum ground wires:

How big aluminum basis wire exercise you need for a 00 AWG aluminum wire?

Just check the aluminum footing wire size table in a higher place and you will encounter that you need a two AWG aluminum ground wire for 00 AWG aluminum wire grounding.

What size ground wire exercise I need for 500 kcmil aluminum wire?

Aforementioned affair. Bank check the NEC equipment grounding usher chart for aluminum wires above, and y'all will come across that you need a 000 AWG aluminum ground wire for fairly grounding a 500 kcmil aluminum wire.

With these two charts, you tin can pretty much figure out how big equipment grounding conductors you demand. If you have any questions, just employ the comments below and we'll endeavor to assist y'all out.