Technically you only need #8 but if you use #8 you have to protect it in conduit. This is the one place where you have to use copper wire, as you cannot direct bury aluminum wire. So, you'll need to get a length of #6 bare copper wire to run from the ground bar in your sub panel to the ground rod outside. You're going to need an additional ground rod for your sub panel because it's a detached garage. The neutral to ground bond should only occur in the main panel or disconnect. You will not install this and simply discard it. I actually like to put one on each side for convenience, just like the neutral bars are.Įvery panel comes with a main bonding jumper, in the form of either a green screw or copper strap. So you'll need to purchase a separate ground bar to install in your sub panel as most do not come with one. You may have noticed that in your main panel, both the white neutral wires and bare copper wires (assuming your house is wired with Romex) are terminated on the neutral bar. The grounds and neutrals in your sub panel need to remain separate. Lastly, I'd like to add a few more pointers to assure you make a safe, code compliant installation. Chances are the service wires coming from your meter to your main panel are aluminum and the wires that the power company ran from the transformer to your meter are definitely aluminum. The reality is, we electricians use aluminum wire for feeders and services pretty much exclusively now days because copper is just too prohibitively expensive. Now, as for your EV charger, some manufacturers recommend copper wiring, and you can certainly use copper wiring from your sub panel to the EV plug. You'll still be saving a ton of money.Īnother thing to consider is that #1 XHHW may not be readily available at your local big box store, so you may have to resort to your local electrical supply house, most of whom have counter sales departments. To aid in making the pull easier, it may be advantageous to up your conduit size to 1-1/2. You can by code stuff 3 x #1 and 1 x #6 XHHW wires into 1-1/4 SCH 80 PVC, but you'll be at about 37% wire fill, which is really close to the NEC maximum of 40%. If you decide the savings is worth it, and you decide to go aluminum, you'll need #1 AWG XHHW wire for the hots and neutral. But you can certainly run the whole thing in SCH 80.Īs for your equipment ground conductor (EGC), you'll need a #8 copper wire or #6 aluminum wire for a 100 amp feeder. The lateral run to the garage can be SCH 40, which will save you some money. So your preformed elbow will need to be SCH 80 as well. In particular, this is generally where the conduit exits the building (usually via an LB conduit body) and to the point where it is below the required burial depth, which is 18" in this case. You'll need 1-1/4 SCH 80 PVC for areas exposed to damage. If you're dead set on copper, #3 THHN is fine. ![]() The cost difference is staggering and there's no measurable disadvantage to using aluminum if it's installed properly. ![]() Note: View additional wire size charts from the list below.First, I would like you to consider using aluminum wiring instead of copper. Wire Size Chart and Maximum Amp Ratings Source: NFPA 70, National Electrical Code, Table 310.15(B)(16) SIZE The wire size chart below shows allowable ampacities of insulated conductors rated up to and includingĢ000 Volts, 60☌ through 90☌ (140☏ through 194☏), not more than three current-carryingĬonductors in raceway, cable, or earth (directly buried), based on ambient air temperature of 30☌ (86☏). The number of devices connected to the circuit usually determines how much current will flow through the wire. It is important to pick the correct size of wire so that the wire doesn't overheat. Limit that a wire can handle before damage occurs. Each wire size, or wire gauge (AWG), has a maximum current
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