Appliance and Specialty Circuits for New Hampshire Homes

What a Dedicated Circuit Is and Why It Matters

A dedicated circuit serves one appliance and nothing else, sized from that appliance's nameplate rather than from what happened to be nearby. For anything heavy it is a requirement rather than an upgrade.

The reason is load and duty cycle together. A hot tub, a well pump, a range or a heat pump draws a lot, and several of them draw it for long periods or start repeatedly. Sharing a circuit with anything else means nuisance tripping at best, and at worst a circuit running near its limit for hours, which is how terminations get hot.

The nameplate is the part that matters. A circuit sized from a category rather than from the actual unit is a guess, and guesses in this direction are either wasteful or unsafe.

We run dedicated circuits across Manchester, Concord, Nashua, Derry, Bedford, Henniker, Laconia and the rural towns, where the well pump and the septic pump are frequently the two most important circuits in the house.

Hot Tub and Spa Circuits

A hot tub is one of the heaviest and most demanding loads a house will add, and it is also the one with the most specific requirements because it combines high current with water.

It needs its own 240 volt circuit sized to the unit, GFCI protection, and a disconnect within sight of the tub but at a required distance from it so somebody can isolate it without reaching over the water. Bonding matters too, tying the metal parts together so there is no voltage difference between them.

The run is usually the variable. A tub on a deck near the panel is straightforward; one at the end of a yard means a buried circuit below the frost line, which in New Hampshire is a real depth and needs routing where a plow will not find it.

It is also a load worth checking against the service before the tub is delivered rather than after, because a hot tub arriving at a house already close to its limit is exactly what the load calculator exists to catch.

Well Pumps and Septic Pumps

On a rural New Hampshire property these are the circuits that matter most, because when they stop the house stops being habitable rather than merely inconvenient.

A well pump has no water pressure fallback. When the power goes or the circuit fails there is no water at all, not reduced flow. A septic pump is the same problem in the other direction. Both are motor loads that draw several times their running figure to start, which is why they belong on their own circuits and why they drive generator sizing on properties that have them.

What we see failing is usually the control side rather than the pump: a pressure switch, a control box, a capacitor, or a connection that has corroded in a damp basement or a well house. A pump that has started tripping its breaker is frequently a pump telling you it is struggling before it fails.

Both are worth having on a circuit that is properly protected and properly labeled, because the day they fail is not the day to be working out which breaker they are on.

Range, Dryer and Kitchen Appliance Circuits

Each of these is a dedicated circuit by requirement, and the sizes differ enough that they are not interchangeable.

An electric or induction range needs a 240 volt circuit sized to the appliance, and induction is frequently a bigger load than the gas range it replaced. An electric dryer needs its own 240 volt circuit. A dishwasher, a garbage disposal, a refrigerator and a built-in microwave each need their own 120 volt circuit.

The common problem in older houses is a kitchen that was given two or three circuits when it needed eight, which produces nuisance tripping that no amount of careful use fixes. Adding circuits is the answer rather than a bigger breaker, and it is cheapest during a remodel while the walls are open.

Where a gas range is being replaced with induction, that is a new 240 volt circuit rather than an appliance swap, and it is worth pricing before the appliance is bought.

Heat Pump and Mini-Split Circuits

Heat pumps are the fastest growing load in New Hampshire houses and they are the change most likely to push a service past what it can carry.

A ducted whole-house system is typically the largest single load a house will ever add, commonly in the region of 40 amps, usually with supplementary electric heat behind it for the coldest days, which is an additional load again. Mini-splits are a different proposition: a single head is modest and even several are considerably less than a ducted system.

Each outdoor unit needs its own circuit sized to its nameplate and a disconnect within sight of it. Indoor heads may need their own supply depending on the system.

The detail that catches people is that heating and cooling count once in the load calculation, at the larger. Replacing central air conditioning with a heat pump is a smaller change than the raw numbers suggest; adding a heat pump to a house with no cooling at all is a bigger one, and that is the case where a service upgrade often comes into it.

Pools, Workshops and Outbuildings

These share a problem, which is that the load is somewhere other than the house and the run is most of the job.

Pool wiring has its own requirements around bonding and GFCI, because water and electricity at close quarters is exactly the scenario those rules exist for. Everything metal in the vicinity gets bonded together, and the equipment sits on protected circuits with a disconnect.

A workshop or garage with real equipment is usually better served by a sub-panel and a feeder than by individual circuits run one at a time. Once there is a welder, a compressor, a dust extractor or a table saw involved, the feeder is cheaper than four separate runs and it leaves room for the fifth thing.

For detached outbuildings the run is buried, below the frost line, routed where it will survive a plow and a snowbank. On the rural properties around Weare, Deering, New Boston and Hillsborough that is frequently a long trench, and it is the part worth planning rather than improvising.

Sizing From the Nameplate, Not the Category

The nameplate on the actual unit is what a circuit is sized from, and this is the single most common place where a job is done approximately rather than correctly.

Two hot tubs of similar size can need different circuits. Two heat pumps rated the same nominal capacity can draw differently. A range from one manufacturer is not the same load as another. Sizing from a category produces a circuit that is either undersized, which is a safety problem, or oversized, which wastes capacity the house may need elsewhere.

It also means the appliance has to be chosen before the circuit is run, which is why in a remodel the appliance schedule is the design. Running a circuit and then buying the equipment is how rough-in ends up in the wrong place.

Where the equipment is not yet chosen, the honest approach is to run the feeder and the route and leave the final sizing until the nameplate exists, rather than guessing and hoping.

Checking the Service Before Adding Load

Every circuit on this page adds to the same service, and adding two or three of them to a house wired when the heat was oil is what puts a 100 amp service past its limit.

The check is a load calculation to Article 220 on what the house will be rather than what it is, and it takes minutes. It counts general lighting from the floor area, the small appliance and laundry circuits, the fixed appliances with their demand factor, heating or cooling at whichever is larger, and anything continuous at 125 percent.

The load calculator runs exactly that, and our guide to what size service a house needs explains what pushes a house past 100 amps.

Where the answer is that the service is short, there are usually three options rather than one, and a service upgrade is only the most obvious of them. Finding that out before the hot tub is delivered is a conversation; finding out afterwards is a problem.