Do I need an electrical panel upgrade? The 100-amp vs. 200-amp reality check

Panel upgrades get sold hard, and some of those pitches are nonsense. But a genuinely undersized or unsafe panel is one of the few home problems where the downside is a fire. Here's how to tell which one you have — and let's be clear up front: the assessment is yours, the work is never DIY. Opening a panel exposes the service lugs, which stay live even with the main breaker off.

First: what size is it?

Open the panel door (just the door, not the cover) and read the main breaker at the top. It'll say 100, 125, 150, or 200. Older homes may have a 60-amp fuse box — if yours does, skip to the bottom; you're upgrading.

• 100 amps was standard through the 1980s. Fine for a smaller home with gas heat, gas range, gas water heater, and no EV.
• 200 amps is the modern standard and what every new build gets. It's what you need if you're adding any two of: EV charger, heat pump, electric range, electric dryer, hot tub, or a workshop.

Signs the panel is actually at its limit

Any one of these is a real signal, not a sales pitch:

• Breakers trip when two big things run — microwave plus toaster, or the dryer plus the AC kicking on.
• Lights dim when the AC or a motor starts. Momentary dimming on a compressor start can be normal; sustained dimming is not.
• No empty slots and tandem (double-stuff) breakers in every available space. The panel is physically full.
• Warm panel cover, buzzing, or a burning smell. Stop reading and call an electrician today.
• Scorch marks or melted insulation visible when the cover is off (if you've had a pro look).

Not a sign by itself: "you have a 100-amp panel." Plenty of homes run fine on 100 amps. It's about load, not the number.

What the big appliances really add

The honest load math an electrician does is a code calculation, but these are the breaker sizes each one claims:

| Addition | Typical circuit | Practical effect on a 100A panel | |---|---|---| | Level 2 EV charger | 40–60A | Usually pushes you over, unless a load-managed charger is used | | Heat pump (replacing gas furnace + AC) | 30–60A plus backup heat strips 40–60A | Almost always requires 200A | | Electric range | 40–50A | Tight with other electric loads | | Electric dryer | 30A | Fine alone | | Hot tub | 50A | Usually the tipping point | | Tankless electric water heater | 100–150A (!) | Needs 200A minimum, often more |

A good electrician can sometimes avoid a full upgrade with a smart load-management device ($500–$1,200) that pauses the EV charger when the range is on. Worth asking about if the only new load is a car.

The two panels you replace no matter what

If your panel is a Federal Pacific Electric (FPE) Stab-Lok or a Zinsco / GTE-Sylvania, replace it. These breakers have a documented history of failing to trip under fault — the breaker stays on while the wire overheats. This isn't a load question. The brand name is on the panel door or the breakers themselves. Insurance companies increasingly decline or surcharge homes with them, which tells you what the actuaries think. Budget $2,000–$4,000 for a like-for-like replacement.

Also flag: Challenger panels (1980s–90s) have a known issue with certain breaker types; most electricians recommend replacement. Pushmatic panels aren't dangerous per se but parts are scarce.

What an upgrade costs in 2026

• 100A → 200A service upgrade: $1,500–$4,000. The range is driven by whether the utility service drop and meter base also need replacing (adds $800–$2,000), the local permit, and whether the panel moves.
• Like-for-like panel swap (same amperage, new panel): $1,200–$2,500.
• Subpanel add (for a garage, shop, or addition): $800–$2,000.
• Utility coordination for a service upgrade typically means a power shutoff of 4–8 hours on install day.

Every panel job requires a permit and an inspection. If a contractor offers to skip the permit for a discount, that's a contractor who'll also skip the torque spec on your lugs.

Why this is never DIY

The breakers you flip are downstream of the main. The lugs where the utility wires land are upstream and are live at 240V any time the meter is in — the main breaker doesn't kill them. Pulling a meter without the utility's authorization is illegal in most jurisdictions and, more to the point, the service conductors can deliver thousands of amps into a mistake. Licensed electricians do this with the utility, with a permit, and with insurance. That's the whole job.

Getting quotes

Panel work has unusually wide price variance because so much depends on the service entrance. Get three bids and ask each one the same two questions: does this include the meter base and service drop if needed, and is the permit and inspection in the price. The Find a Pro page pulls two to four licensed electricians in your zip within a day. If you're also comparing it against other electrical projects, the cost planner has the smaller jobs priced.