200 Amp Service Wire Size: Copper, Aluminum & Conduit

01The typical conductors: 2/0 copper or 4/0 aluminum

For a 200-amp dwelling service, the two standard answers are 2/0 AWG copper or 4/0 AWG aluminum. These come from NEC 310.12, the dwelling-service rule that lets a single-family home's main service and feeder conductors be sized at 83 percent of the service rating (200 A x 0.83 = 166 A), then matched to the 75-degree-C column of Table 310.16. Under that allowance, 2/0 copper and 4/0 aluminum each land at the right ampacity for 200 amps in a residential service, which is why they are the conductors you see again and again.

Aluminum is the more common pick for service entrances and panel feeders purely on cost: copper carries the same current in a smaller conductor but runs several times the price per foot, so utilities and electricians default to 4/0 aluminum (often as an SE or SER cable with a 4/0-4/0-2/0 makeup, the two hots and a reduced neutral) unless there is a reason to use copper. The aluminum versus copper trade-off also drives how branch circuits are sized and what inspectors flag. Copper appears where space is tight, where terminations require it, or where the run is very long and the smaller copper conductor eases conduit fill.

Note that these sizes use the dwelling-service exception, not the general ampacity table. A general feeder elsewhere in the building at 200 amps would need larger conductors (3/0 copper or 250 kcmil aluminum at 75 C). Mixing up the dwelling-service allowance with a general feeder is one of the most common sizing errors, and it is exactly the kind of distinction an electrician and an inspector exist to get right.

02Conduit and raceway sizing

When the service conductors run in conduit rather than as a cable, the raceway has to satisfy the NEC Chapter 9 fill tables. For three 4/0 aluminum or three 2/0 copper service conductors plus a neutral, a 200-amp service commonly uses 2 inch conduit, with 2.5 inch where a larger neutral, an equipment grounding conductor, or a generous fill margin is wanted. The exact size depends on the conductor insulation type (THWN-2 packs tighter than older insulations) and how many conductors share the raceway.

For a service mast (the vertical conduit carrying overhead service drop conductors up through the roof), the mast must also be mechanically strong enough to withstand the pull of the utility drop, which often pushes the size toward 2 inch rigid metal conduit regardless of the fill calculation. Underground services in a buried raceway have their own depth and conduit-type requirements. If the upgrade also moves or replaces the meter enclosure, a meter box and weatherhead replacement is a separate line you may see on the quote. These are the details where the printed code tables, the local utility's service standards, and the inspector's sign-off all have to agree before power is connected.

03Grounding electrode conductor sizing

The grounding electrode conductor (GEC) ties the service neutral and panel to the grounding electrode system: the ground rods, the metal underground water pipe, and any concrete-encased electrode. Its size comes from NEC Table 250.66, which is based on the size of the largest service conductor. For a 200-amp service using 2/0 copper or 4/0 aluminum service conductors, the table calls for a 4 AWG copper (or 2 AWG aluminum) grounding electrode conductor in the typical case.

There is an important wrinkle: when the only electrode is a made electrode like a driven ground rod, NEC 250.66(A) caps the required GEC to that rod at 6 AWG copper, because a ground rod cannot carry more than that anyway. So a 200-amp service often has a 4 AWG copper GEC to the water pipe and concrete-encased electrode but only needs 6 AWG to the ground rods. Getting these sizes and the bonding right is fundamental to safety: the grounding system is what gives fault current a path to clear a breaker and what limits voltage during a surge or lightning event.

The neutral (grounded conductor) and the main bonding jumper also have minimum sizes tied to the service, and the whole grounding and bonding scheme has to be assembled as a system. This is precisely the part of a service that homeowners get wrong, and getting it wrong is invisible until a fault or a surge finds the gap.

04Why this is utility and permit territory, not DIY

A service upgrade is not an inside-the-house wiring project you can do on a Saturday. The service-entrance conductors connect to the utility's system, so the work requires coordinating a power disconnect and reconnect with the utility, and in most jurisdictions only a licensed electrician (and often only the utility itself for the drop or lateral) may touch the meter and service connections. The conductors are large, energized at the full available fault current of the transformer, and unprotected ahead of the main breaker, which makes a mistake here categorically more dangerous than a branch-circuit error.

On top of the physical danger, a service upgrade is permitted and inspected work, with the panel, meter base, mast or lateral, grounding, and conductor sizing all checked against code and the local utility's service standards before power is restored. The permit and inspection are not bureaucracy; they are what confirm the grounding system will actually clear a fault and that the conductors are sized for the load. For all of these reasons, a 200-amp service upgrade is a job to hire a licensed electrician for, full stop. The value of knowing the wire sizes is understanding the quote, not doing the install.

05Cost context for a service upgrade

Upgrading to a 200-amp service typically runs $2,000 – $4,500 installed, covering a new panel, meter base, service-entrance conductors, the mast or lateral, the grounding system, the permit, and the inspection. Installed pricing for a 200-amp service upgrade breaks these line items down further, and homes needing more capacity can compare the jump to a 400-amp service. The spread depends on whether you are upgrading from 100 or 150 amps, whether the service is overhead or underground, how far the run is, and what the utility requires at the meter. Conductor material is part of it: aluminum service cable keeps the conductor cost down, which is one reason 4/0 aluminum is the default rather than 2/0 copper.

Add-ons move the number quickly. An underground service with trenching, a long run from a distant transformer or weatherhead, panel relocation, or a meter base replacement each add cost, sometimes pushing a complex job well past $5,000. When you collect quotes, the conductor sizes above are your check that the electrician is specifying a genuine 200-amp service and not under-sizing the entrance to shave the bid.