Somebody has probably told you that you need a 200-amp panel.
Maybe it was a hot tub installer. Maybe it was an HVAC tech, or the EV charger company, or an electrician who looked at your box for about ninety seconds. And maybe they were right. But you are entitled to know why, and “your panel is old” is not a why.
Here is how service capacity actually works, how to get a rough read on your own home, and what an honest load calculation looks like.
What “100-amp service” and “200-amp service” actually mean
Amperage is the total amount of electrical current your utility service and main panel can safely deliver to the house at one time. It is a ceiling, not a bill. You are not charged for having 200-amp service any more than you are charged for having a four-lane driveway.
Most homes in the Moore and OKC metro fall into three groups:
- 60 amps. Homes built before roughly 1960 that were never updated. Rare now, and almost always undersized for any modern use.
- 100 amps. The standard for a great many homes built from the 1960s through the 1990s. Still perfectly adequate for a lot of households.
- 200 amps. The current default for new residential construction and the target for most upgrades.
You can usually find yours by opening the panel door and reading the number stamped on the main breaker at the top. That number is your service size. You do not need to remove any covers to see it.
The real question is not the number. It is the math.
Here is the thing most sales conversations skip: a 100-amp service is not automatically inadequate, and a 200-amp service is not automatically necessary. What matters is your actual connected load, and that is a calculation, not an opinion.
A simplified version of what an electrician runs:
- Start with the square footage of the home for general lighting and receptacles.
- Add fixed appliance loads: range, oven, water heater, dryer, dishwasher, disposal.
- Add HVAC, using the larger of heating or cooling, since they do not run simultaneously.
- Add any dedicated loads: hot tub, pool equipment, well pump, shop, EV charger.
- Apply the demand factors in the National Electrical Code, which account for the fact that not everything runs at once.
The result is a number in amps. If it lands comfortably under your service size, you have room. If it is close to or over it, you do not.
This is a fifteen-minute exercise for someone who does it regularly. It is also the single most common step that gets skipped before a panel upgrade is recommended, which is exactly why so many homeowners feel like they are being guessed at.
When 100 amps is genuinely still fine
Do not spend money you do not need to spend. A 100-amp service often has plenty of headroom for a home with:
- Gas heat, gas water heater, and a gas range or dryer
- One central air system of ordinary size
- No hot tub, pool, EV charger, or detached shop
- Under roughly 2,000 square feet
If that is your house and your panel is in good physical condition, an upgrade is not urgent. What you may actually need is a subpanel, a dedicated circuit, or a repair. Those are much smaller jobs and any electrician worth hiring should offer them first.
When 200 amps is the honest answer
The picture changes when the load stacks up. A 200-amp service becomes the right call when you have, or are about to have, several of these:
- Electric heat, especially a heat pump with resistance backup. This is the single biggest load in most homes that has it.
- An EV charger. A Level 2 charger typically adds 30 to 60 amps of continuous demand. That is the equivalent of adding another kitchen. This is why “just install the charger” often turns into a service conversation, and it is worth reading how we approach EV charger installation before you take a quote from anyone.
- A hot tub or pool equipment. Typically 40 to 60 amps on a dedicated circuit.
- A whole-home standby generator with an automatic transfer switch. The transfer equipment has to match the service.
- A detached shop, garage, or ADU fed by a subpanel.
- A physically full panel with no open slots and tandem breakers already doubled up.
- An addition or a whole-home remodel that is adding circuits.
And one symptom that outranks all of the above: lights across the house that dim noticeably when the AC or the well pump kicks on, combined with breakers tripping on more than one circuit. If you are seeing that, start with why your breaker keeps tripping, then come back here.
Why you should be a little skeptical of a fast panel-upgrade quote
There is a well-documented pattern in this industry, and homeowners in Oklahoma City forums complain about it regularly: a customer calls about one specific thing, an EV charger or a spa hookup, and the visit turns into a five-figure panel proposal before anyone measured anything.
Sometimes the upgrade is real. Panels do run out of capacity, and a genuinely undersized service is not something to work around with creative wiring.
But the difference between a real recommendation and a soft one is evidence. Before you agree to a service change, you should be able to get straight answers to four questions:
- What is my calculated load, and what is my service size?
- Which specific loads are pushing me over?
- Is there a smaller option, such as a subpanel, a load management device, or a dedicated circuit?
- What is the written price, and does it include the permit, the inspection, and the utility coordination?
An electrician who is doing this honestly will not mind the questions. If the questions cause friction, that is your answer.
What a service change involves in Moore and OKC
Worth knowing before you commit, because the scope surprises people.
A panel upgrade is not just swapping a box. It usually includes a new meter base, new service entrance conductors, a new grounding and bonding system brought up to current code, the panel itself, and re-terminating every circuit in the house. Grounding, bonding, and surge protection requirements have all changed across recent code cycles, so a panel going in today is held to a different standard than whatever was current when your original panel was installed.
It requires a permit and an inspection in both Moore and Oklahoma City, and those permits can only be pulled by a contractor licensed with the Oklahoma Construction Industries Board and registered with the city. It also requires coordinating a power disconnect and reconnect with OG&E, which means your power will be off for part of a day.
That is a real project. It should come with a real explanation, and our panel upgrade and service change page walks through how we scope it.
Frequently asked questions
How do I find out if I have 100-amp or 200-amp service?
Open the panel door, do not remove the interior cover, and read the amperage stamped on the main breaker at the very top of the panel. It will say 100, 125, 150, or 200. If there is no main breaker in the panel, the main disconnect may be outside near the meter.
Does a 200-amp panel raise my electric bill?
No. Service size is a capacity ceiling, not consumption. You pay for the electricity you use, not the capacity available to you.
Can I add an EV charger to a 100-amp panel?
Sometimes, yes. It depends on your calculated load and what else the home runs. Options include a lower-amperage charger setting, a load management device that prevents the charger and a large appliance from running simultaneously, or a dedicated circuit if there is capacity. A load calculation tells you which of these is available before anyone talks about a new panel.
How long does a panel upgrade take?
For a typical residential service change, most of one working day, with the power off for a portion of it, plus scheduling around the utility disconnect and the city inspection.
Do I need a permit for a panel upgrade in Moore, Oklahoma?
Yes. Panel replacements and service changes require a permit and inspection, and the permit must be pulled by a state-licensed, city-registered contractor. Work done without one is work no inspector ever reviewed, which can create problems at resale or during an insurance claim.
Get the number before you get the quote
If someone has told you that you need a 200-amp service, get a second read from someone who will show you the load calculation.
We are a licensed, local, owner-run electrical company in Moore. We will look at your panel, run the math, and tell you honestly whether you need the upgrade or whether something smaller solves it. Estimates are free and the price is in writing before we start.
Call or text (405) 212-5300, or request your free estimate.
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