200 Amp Meter Base: What Class 200 Means and Which Type You Need

Nearly every 200 amp house has one outside, and most owners only notice it when a quote lists a "new meter base."

Short answer: a 200 amp meter base is a Class 200 meter socket: the outdoor enclosure the utility's meter plugs into, rated to carry 200 amps continuously. It is the standard meter base for residential services up to 200 A. Models differ in cover type (ring or ringless), bypass, overhead or underground entry, and whether a main breaker shares the enclosure, and your utility decides which ones it will set a meter in.

What does "Class 200" mean?

"Class" is the continuous current rating: a Class 200 meter and socket carry up to 200 A continuously. Meter classes come from the ANSI C12 metering standards, the socket is a listed product built to UL 414, and the meter nameplate shows "CL200". Meter base, meter box and meter socket all name the same enclosure, though stores also file meter-main combos under "meter box" (more below).

The socket rating is a ceiling, not the service rating. NEC 230.66 requires a meter socket to be listed and rated for the voltage and ampacity of the service, so a 200 A socket can serve a 100, 125, 150 or 200 A service; the disconnect, the conductors and the utility's supply set the actual rating. The whole chain is in meter socket and service entrance explained.

Why do 200 amp services use a Class 200 socket?

Because it covers everything a 200 A disconnect can deliver. A standard breaker carries continuous load up to 80% of its rating, so a 200 A main allows 200 × 0.80 = 160 A continuous and up to 200 A non-continuous. A socket rated 200 A continuous clears both. A 400 A service allows 400 × 0.80 = 320 A continuous, which is why it gets a Class 320 socket. The older, smaller size is in 100 amp meter base.

The choices on a 200 amp meter base

Five things separate one 200 A socket from another, and the utility settles most of them.

Ring or ringless

On a ring-type socket, a separate sealing ring clamps the meter to the cover. On a ringless socket, the cover itself traps the meter and carries the seal. Many utilities specify one style, some accept both; see ringless vs ring-type meter socket.

Bypass

A bypass lets the utility pull the meter without cutting power to the house. Many 200 A sockets have no bypass, some have horn bypass terminals the utility can jumper, and some utilities require a lever bypass, explained in lever bypass meter socket.

Overhead or underground feed

An overhead socket takes the conductors through a hub on top, from the mast or service cable. An underground socket takes the utility's lateral from below through a riser, and utilities often specify an underground-rated socket with room to bend and terminate those conductors, which they often own up to the line-side terminals. Dual-rated sockets have a removable hub and bottom knockouts. See overhead vs underground service.

4-jaw or 5-jaw

A single-family 120/240 V service uses a 4-jaw socket. A 5-jaw socket adds a neutral terminal for units fed by two legs of a 120/208 V system, as in many apartment buildings.

Plain socket or meter-main

Many "200 amp meter box" listings are meter-mains: a 200 A socket and a 200 A main breaker in one enclosure, giving an outdoor shutoff and turning the indoor panel into a downstream panel. A plain socket leaves the main breaker indoors. How to choose, including the NEC 230.85 outdoor emergency disconnect where adopted, is in meter main combo vs separate meter and panel.

When is a 200 amp meter base not enough?

When the load calculation says the house needs more than a 200 A service, as a large all-electric house, two high-amperage EV chargers or an ADU on the same service can; see 200-amp vs 400-amp service and run your numbers with the home electrical load calculator.

The next common step is 400 A on a Class 320 socket. A Class 200 socket cannot be re-rated in place, so moving up is a service upgrade: new socket, new conductors, a grounding review and utility coordination. See service upgrade vs panel replacement.

Do you need a surge protector when the meter base is replaced?

Only if the job also replaces the service equipment, meaning a meter-main or the main-breaker panel; then NEC 230.67 applies, and since the 2020 edition a dwelling service needs a Type 1 or Type 2 surge protective device, including where service equipment is replaced. The Leviton P2120-B is a Type 1 unit made for service-entrance installs and meter-adjacent mounting, the fit for an outdoor meter-main.

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For an indoor main-breaker panel, a Type 2 unit that mounts beside any brand of load center, such as the Siemens BoltShield FSPD140, is the alternative; your electrician and inspector decide.

The rest of the job, from warning signs to the utility reconnect, is in meter base replacement.

How are the conductors to the panel sized?

By the electrician, from the load calculation (NEC 230.42). For 120/240 V single-phase dwelling services rated 100 to 400 A, NEC 310.12 permits conductors with at least 83% of the service rating when they supply the entire dwelling load.

Illustration only. Assumptions: a 200 A single-phase dwelling service, one set of conductors supplying the whole load, 75°C terminations (NEC 110.14(C)), no more than three current-carrying conductors together, 30°C (86°F) ambient.

• 200 A × 0.83 = 166 A minimum ampacity
• Smallest Table 310.16 conductor at 75°C that meets 166 A: 2/0 copper (175 A) or 4/0 aluminum (180 A). One size down, 1/0 copper (150 A) and 3/0 aluminum (155 A), fall short.
• Where 310.12 does not apply, Table 310.16 alone at 200 A gives 3/0 copper (200 A) or 250 kcmil aluminum (205 A).

That is why 4/0 aluminum is the common cable on residential 200 A services. Change any assumption and the answer changes, and on an underground service the conductors up to the socket are often the utility's. Full chart: 200 amp wire size. Use it as a sanity check on a quote, not as a spec.

How to tell what you have

From the ground, without opening anything:

• Meter nameplate: "CL200" is the meter's class, not proof of a 200 A socket, since utilities commonly use Class 200 meters on smaller services too.
• Main breaker and the cable from the meter: a 200 A main fed by 4/0 aluminum is the usual 200 A signature; full method in how to tell if you have 100 or 200 amp service.
• The meter's rim: a separate metal band means ring-type; none means ringless.
• The conduit: from the top means overhead; from below, underground.
• The socket label is inside the sealed enclosure, so ask the utility or an electrician for the rating.

Do not pull the meter, break the seal, or remove the socket cover. The line side is always energized.

Why is this electrician work?

Everything in the meter base is on the line side: no breaker of yours protects it, and only the utility can de-energize it. Replacing one means utility coordination, a permit, large conductors torqued to the manufacturer's specification, and a grounding review. It is licensed, permitted and inspected work.

Standards and code reference

• NEC 110.14(C): termination temperature limits
• NEC 230.42: service-entrance conductor ampacity from the calculated load
• NEC 230.66: meter sockets listed and rated for the voltage and ampacity of the service
• NEC 230.67: Type 1 or Type 2 surge protective device on services supplying dwelling units, including where service equipment is replaced (2020 NEC onward)
• NEC 230.85: outdoor emergency disconnect for one- and two-family dwellings (2020 NEC onward)
• NEC 310.12: 83% allowance for 120/240 V single-phase dwelling services from 100 to 400 A
• NEC Table 310.16: conductor ampacities
• UL 414: meter sockets; ANSI C12 series: utility metering standards, including meter class

Code editions and local amendments vary. Confirm the adopted edition with your AHJ, and treat manufacturer instructions as governing wherever they are more restrictive.

Where to go next

• 320 amp meter base
• 100 amp meter base
• Meter main combo vs separate meter and panel
• Who owns what on your electrical service
• Size the service: home electrical load calculator

More in our electrical panel guides.