# What are the electrical requirements for a mini split?

> What a mini split needs electrically: a 240-volt dedicated circuit, a disconnect by the outdoor unit, panel capacity, and Portland and Vancouver permits.

URL: https://firlandsportlandminisplits.com/guide/mini-split-electrical-requirements/

Learn

The circuit, the disconnect, the panel and the permit, and what changes in an older Portland house.

Last Updated: November 12, 2026

The short answer

Most mini splits need their own 240-volt circuit from the panel to the outdoor unit, sized to the amps on the unit's nameplate, with a disconnect switch within sight of it. The heads usually take power from the outdoor unit through the communication cable. Your panel needs two open breaker spaces and enough spare capacity.

Key takeaways

- One dedicated 240-volt circuit per outdoor unit is the usual setup.
- The breaker size comes from the nameplate, not a rule of thumb.
- A disconnect switch sits within sight of the outdoor unit.
- A full or undersized 100-amp panel can need a service upgrade first.

Before a mini split goes on the wall, the panel has to be able to feed it. On every visit, [Firlands Portland Mini Splits](https://firlandsportlandminisplits.com/) opens the panel, reads the outdoor unit’s nameplate requirements against it, and puts the circuit and any panel work on the written estimate. Here’s what goes into that.

## The circuit: dedicated and 240 volts

Each outdoor unit gets its own circuit from the panel, with nothing else on it. For almost every system, that’s a 240-volt circuit using a two-pole breaker.

### Sized from the nameplate

Every outdoor unit lists a minimum circuit ampacity (MCA) and a maximum overcurrent protection (MOCP) on its nameplate and in its manual. The wire is sized to the first and the breaker to the second. A small single-zone unit may call for a 15- or 20-amp breaker; a large multi-zone outdoor unit can call for 30 amps or more.

### What feeds the heads

On most systems, the heads don’t get their own circuit. A four-wire communication cable runs from the outdoor unit to each head alongside the refrigerant lines, carrying both power and control signals. Some ducted air handlers are the exception, and the manual says so.

## The disconnect by the outdoor unit

The electrical code requires a way to cut power at the outdoor unit, within sight of it, so whoever services it can make it safe without walking to the panel.

That’s a small weatherproof box on the wall next to the unit, with a pull-out or a switch inside. It sits beside the line-hide, and on a painted house it can be painted to match. We place it where it’s easy to reach but not in a walkway.

## Is your panel big enough?

Your panel needs two open breaker spaces for each new 240-volt circuit and enough spare capacity for the new load. Either can be the problem.

### Space

A panel with no open spaces can sometimes take a tandem breaker or have circuits reorganized. That depends on the panel’s make and labeling, and some older panels allow neither.

### Capacity

Capacity is about the total load. A load calculation adds up the house’s big draws and compares them with the service size.

Many older Portland houses have a 100-amp service, which is often enough for a mini split on top of gas heat and a gas range. It gets tight when the house already has electric heat, an electric range, an electric dryer, a hot tub or an EV charger.

| Situation | What usually happens |
| --- | --- |
| Open spaces, capacity to spare | A new circuit, done on install day |
| No open spaces, capacity to spare | Tandem breakers or reorganized circuits, where the panel allows |
| Capacity tight on a 100-amp service | A load calculation decides; a service upgrade may come first |
| Old fuse box or an obsolete panel | Replacement before new loads are added |

### When the service needs an upgrade

Firlands’ typical range for a panel or service upgrade from 100 to 200 amps is $2,500 to $6,000, as separate electrical scope. It needs PGE or Pacific Power to reconnect the service, so it’s planned ahead of install day. We tell you at the visit if your panel needs it.

## Replacing baseboards frees up capacity

If the mini split is replacing electric baseboard or wall heaters, the old heater circuits come out of the load. That often frees enough capacity on a 100-amp panel that no upgrade is needed.

A heat pump moves heat rather than making it, so the outdoor unit draws less than the baseboards it replaces for the same warmth. See [baseboard heat to mini split](https://firlandsportlandminisplits.com/baseboard-heat-to-mini-split/) for how we plan those jobs, and the [electric bill guide](https://firlandsportlandminisplits.com/guide/mini-split-electric-bill/) for running costs.

## Old wiring in old houses

Many pre-1940 Portland houses still have some knob-and-tube wiring. The mini split doesn’t run on it: it gets a brand-new circuit straight from the panel.

What the old wiring can affect is the panel. A house with knob and tube often has an older fused panel or an undersized service, and those come up at the visit. We note what we see and tell you before we price the job ([adding air conditioning to an old Portland house](https://firlandsportlandminisplits.com/guide/adding-air-conditioning-to-an-old-portland-house/)).

## Permits and who does the wiring

The new circuit is electrical work with its own permit, separate from the mechanical permit for the heat pump.

### In Oregon

Oregon law (ORS 479.620) requires an electrical contractor license to do electrical installations. The state’s limited HVAC maintenance label covers repairing or replacing equipment, not running a new circuit.

- **Portland:** the electrical permit for a first new branch circuit is $174, plus $21 for each additional circuit, with the state surcharge on top. We include the city fees in your price.
- **Gresham, Milwaukie and Lake Oswego:** each city issues its own electrical permits.
- **Oregon City, West Linn and Happy Valley:** Clackamas County handles electrical while the city handles mechanical.
- **Replacements:** swapping an old system for a new one can often reuse the existing circuit if it matches the new nameplate ([mini split replacement](https://firlandsportlandminisplits.com/mini-split-replacement/)). [Mini split permits in Portland](https://firlandsportlandminisplits.com/guide/mini-split-permit-portland/) has the details.

### In Vancouver and Clark County

Washington draws the line in a similar place. Under WAC 296-46B-920, an HVAC/refrigeration specialty electrician can wire the equipment but may not install a new branch circuit from the panel. Bidding electrical work in Washington takes a Washington electrical contractor license (RCW 19.28.041). Inside Vancouver city limits, the City issues the electrical permit rather than the state.

## What the electrical part costs

For a standard install, the new circuit, the disconnect and the city electrical permit are inside Firlands’ typical range for the system.

Firlands’ typical range for a single-zone install is $4,000 to $8,500, including the circuit and permits. A service upgrade is priced separately. The [cost guide](https://firlandsportlandminisplits.com/guide/mini-split-installation-cost-portland/) breaks down every range, and the [installation process](https://firlandsportlandminisplits.com/guide/mini-split-installation-process/) shows where the electrical work falls on install day. For a whole-house plan, see [multi-zone installation](https://firlandsportlandminisplits.com/multi-zone-mini-split-installation/).

## Questions about this guide

### Are mini splits 110 or 220 volts?

Most are 208/230-volt units, what people call 220 or 240. A few small single-zone models run on 115 volts, but they're limited in size and still need their own circuit. For anything that heats a Portland room through winter, we plan a 240-volt circuit.

### Can a mini split share a circuit with something else?

No. The outdoor unit gets a dedicated circuit sized to its nameplate. Sharing a circuit with a dryer, an outlet or another unit risks nuisance trips and overloads, and the electrical inspector won't pass it.

### Does each indoor head need its own circuit?

Usually not. On most systems the heads are powered from the outdoor unit through the four-wire communication cable that runs with the line set. A few larger ducted air handlers need a separate circuit; the installation manual says which.

## Related service

- [Service**Multi-zone installation** Multi zone mini split installation: two to five rooms on one outdoor unit, each head sized to its own room and set to its own temperature.](https://firlandsportlandminisplits.com/multi-zone-mini-split-installation/)

## More guides

- [Learn**What happens during a mini split installation?** The mini split installation process, every step from the first call to the city's final inspection, and what you get at the end.](https://firlandsportlandminisplits.com/guide/mini-split-installation-process/)
- [Cost Guide**How much does mini split installation cost in Portland?** Typical ranges by job, what moves the number, and the public costs inside it.](https://firlandsportlandminisplits.com/guide/mini-split-installation-cost-portland/)
- [Learn**Do you need a permit for a mini split in Portland?** Which permits a new or replacement mini split needs, what they cost, and which office issues them outside Portland.](https://firlandsportlandminisplits.com/guide/mini-split-permit-portland/)

## Get an estimate for your house

(971) 458-4515