Service Upgrade

100 to 200 amps: what the utility does, what the electrician does, what it costs.

8 articles

Will a 125 amp service run an electric range?

Adding an electric range to a 125 amp service

33.3A of added demand

your existing calculated load has to be under 92 A for this to fit

Added demand8,000 VA at 240 V	33.3A
Existing load must stay under	92A
Share of the service this takes	27%
Existing service	125 A
What is being addedNEC 220.55 puts one range up to 12 kW at an 8 kW demand	an electric range

Notes

Do not let anyone guess your existing load, including this page. NEC 220.87 gives the real method: take the highest demand recorded in the last 12 months from the utility, multiply by 1.25, and that is your existing load. Most utilities will supply the figure on request; where there is not a year of history, a recording ammeter left on the service for 30 days does the same job. That measured number, plus the 33.3 A above, is the answer.
27% of the service goes to this one thing. Whether it fits depends entirely on what the rest of the house already draws. Under 92 A of existing calculated load and it fits; over, and the service has to grow.
This is not a continuous load, so it counts at its demand figure rather than 125%. Ranges and dryers get further relief in NEC 220.55 and 220.54 because they cycle: a 12 kW range is counted at 8 kW, since the elements are never all on at full for long.
Load management can save the upgrade, and it is worth pricing first. An EV charger with a load-management device, or an energy-management system that sheds the charger when the range comes on, is a listed and code-recognised way to add a large load to a service that could not otherwise take it. It is frequently a fraction of the cost of a new service.
A panel swap and a service upgrade are different jobs. If the panel is full but the service is adequate, a subpanel or a panel with more spaces solves it for far less. If the calculated load exceeds the service, new breakers change nothing — the conductors from the utility, the meter base and the mast all have to grow.

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Service upgrade check

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Cost to Upgrade From 100 to 200 Amp Service, Line by Line
The panel is the cheap part. The meter socket, the service conductors, the grounding and whatever the inspector finds behind the old panel decide whether the bill is $2,000 or $5,000.
Service Upgrade vs Panel Upgrade: Two Jobs With the Same Name
A new panel does not give a house more power. Only the service conductors, the meter socket and the utility connection decide how many amps come in.
Meter Base With Disconnect: What It Is and When Code Requires One
Putting the main breaker outside changes what the panel inside is. Whether it becomes a subpanel, with separated neutrals and grounds and a four-wire feeder, depends on which of three options you choose.
What a Service Upgrade Involves, From Quote to Reconnect
The electrician's part is usually one day. The permit, the utility's disconnect and reconnect, and the inspection in between set the real schedule.
Grounding and Bonding — The Part of the Service Nobody Sees
The grounding system does nothing at all until something goes wrong, which is why it is the part most often found inadequate.
Load Management — Adding Big Loads Without a Bigger Service
The question is not whether the house can supply everything at once. It is whether everything ever needs to run at once.
Overhead vs Underground Electrical Service: Differences, Clearances and Converting
A capacity upgrade almost never requires changing from overhead to underground. Converting is a separate project, usually paid by the homeowner, with trenching, conduit and a utility agreement.
Permits and Inspection — What They Cost and What They Catch
The reason to pull a permit is not the rule. It is that somebody who does not work for the contractor looks at the job.