Residential Electrical 100%

2021 IRC Chapter 41

Lesson 11: Appliances, HVAC Equipment, and Disconnects

IRC E4101, E3702.11 (NEC 422, 440) · 14 practice questions

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Reading

This lesson covers fixed and cord-connected appliances: how a technician disconnects one safely for service, how a range or a dryer gets its equipment ground, and how an air conditioning condenser gets matched to a circuit. GCHS runs into every one of these in rehab work, because appliance replacement is one of the most common line items on a scope of work, and the disconnect and grounding rules are exactly where an otherwise good installation gets flagged.

Appliance disconnect within sight and reading an HVAC nameplate A diagram showing an air conditioning condenser and its disconnect within a 50 foot unobstructed sight line, and a nameplate panel showing minimum circuit ampacity and maximum overcurrent protection values used to size the conductor and the breaker. Disconnect within sight Condenser Disconnect Unobstructed sight line Visible and not more than 50 ft away Reading the nameplate Min. Circuit Ampacity: 19.5 A Max. Overcurrent Protection: 30 A Conductor sized ≥ 19.5 A (12 AWG) Breaker: the 30 A size marked Never size the breaker above the nameplate max
A condenser disconnect must be within sight of the unit (a lockable breaker elsewhere is not enough for a condensing unit), and its nameplate sets both the minimum conductor size and the breaker size.

The basic disconnect rule

Every permanently connected appliance rated over 300 volt-amperes needs a disconnecting means (E4101.5, Table E4101.5), and the code gives two ways to satisfy it: a branch-circuit switch or breaker within sight of the appliance, or one in any location that is capable of being locked in the open position (E4101.8), so nobody can restore power while a technician is working. A permanently connected appliance of 300 volt-amperes or less can use its branch-circuit overcurrent device the same way. "Within sight" has a specific meaning in the code, not a general sense of "somewhere nearby": the Chapter 35 definition says visible and not more than 50 feet from the equipment. A breaker in a panel around the corner and out of view does not qualify unless it can be locked open. Air-conditioning condensing units and heat pumps are stricter: a readily accessible disconnect within sight of the unit is the only allowed means.

Unit switches in a one-family dwelling

Some appliances, disposals and some furnaces among them, have their own built-in unit switch with a marked "off" position. Table E4101.5 lets that unit switch serve as one disconnecting means where an additional individual switch or circuit breaker serves as the other required disconnecting means. For a motor-operated appliance over 1/8 horsepower with a unit switch that opens all ungrounded conductors, the table adds that the other switch or breaker then need not be within sight of the appliance. The unit switch alone, with no second means, does not satisfy the requirement.

Cord-and-plug appliances: the household range

An appliance listed for cord-and-plug connection, a household electric range for example, can use its attachment plug and receptacle, or a separable connector, as the disconnecting means, provided with access (Table E4101.5). "Access" matters in practice: the plug and receptacle have to be reachable for operation and inspection, and nobody is going to dismantle cabinetry or drag a fixed appliance out of its space to unplug it during a grease fire.

Dishwashers and disposals: cord length and an accessible receptacle

E4101.3 and Table E4101.3 limit appliance cords: an in-sink waste disposal cord runs 18 to 36 inches, a built-in dishwasher cord 36 to 78 inches (measured from the face of the plug to the plane of the rear of the appliance), a trash compactor 36 to 48 inches, and a range hood 18 to 48 inches. The receptacle has to be accessible and placed where it avoids physical damage to the cord. A built-in dishwasher's receptacle belongs in the space adjacent to the dishwasher, with a bushing or grommet where the cord passes through an opening, and the receptacle for a cord-and-plug range hood needs its own individual branch circuit. Two failures show up constantly in rehab work: a disposal cord coiled up under the sink well past 36 inches, sitting in the wet, cluttered space under a drain trap, and a dishwasher receptacle in the adjacent cabinet behind a permanently fastened panel, where the only way to reach it is to pull the dishwasher back out. Both defeat the purpose of a cord-and-plug disconnect, which is to give someone a fast, visible way to kill power to that one appliance.

Key numbers
  • Disconnect required for permanently connected appliances rated over 300 VA (E4101.5, Table E4101.5)
  • "Within sight": visible and not more than 50 ft from the equipment (Chapter 35 definition)
  • Unit switch with a marked OFF position: may serve as one disconnect where an additional switch or breaker is the other required means
  • Cord-and-plug appliance, including a household range: plug and receptacle may be the disconnect if provided with access
  • Cord lengths (Table E4101.3): disposal 18 to 36 in.; dishwasher 36 to 78 in.; trash compactor 36 to 48 in.; range hood 18 to 48 in.; receptacle left accessible
  • New range and dryer circuits: 4-wire, equipment grounding conductor separate from the neutral (E3908.7, E3908.8)
  • AC/HVAC equipment (E3702.11): conductor ampacity not less than the nameplate minimum circuit ampacity; breaker the size and type marked on the equipment; condensing unit disconnect readily accessible and within sight, not on an access panel
  • Water heater disconnect: within sight, or a breaker capable of being locked open (over 300 VA)

Ranges and dryers: three-wire versus four-wire grounding

Older range and dryer circuits used a 3-wire connection where the neutral conductor doubled as the path back to the appliance frame. That allowance is gone for new work: E3908.7 bars connecting the grounded conductor to noncurrent-carrying metal parts of equipment or to equipment grounding conductors on the load side of the service disconnect, and E3908.8 bars using it to ground equipment metal parts. A new range or dryer circuit therefore runs 4 wires, with a separate equipment grounding conductor and the bonding strap between the neutral terminal and the frame removed at the appliance. The reason is straightforward: if a shared neutral conductor ever opens, on a 3-wire setup the appliance cabinet itself can become energized. An existing 3-wire branch circuit in an occupied house is not automatically a violation; R102.7 lets the legal occupancy of an existing structure continue without change unless the building official finds a safety concern, and the load-side grounding rules above govern new circuits, which have to be 4-wire from the start. Knowing which side of that line a given job sits on is what separates a defensible correction notice from one that oversteps what the code actually requires.

Air conditioning and HVAC equipment: reading the nameplate

An outdoor condensing unit's nameplate carries two numbers that do the sizing work for the whole circuit: minimum circuit ampacity, sometimes printed MCA, and maximum overcurrent protection, sometimes printed MOP or MOCP. E3702.11 requires the branch-circuit conductors to have an ampacity not less than the minimum circuit ampacity marked on the equipment, and says the branch-circuit overcurrent device rating is the size and type marked on the appliance. E3705.5.4 lets an air-conditioning circuit be protected that way even where the small-conductor limits would otherwise cap the breaker lower. A larger breaker than the nameplate marks is never permitted. The disconnect for the condenser has to be within sight of it and readily accessible (Table E4101.5); it may be mounted on or within the unit, but never on an access panel the technician has to remove to service the unit, or where it hides the nameplate, since that puts the disconnect out of sight the moment the equipment is opened up for work.

A worked example: a condenser's nameplate reads minimum circuit ampacity 19.5 amperes and maximum overcurrent protection 30 amperes. The branch-circuit conductors need to be sized for at least 19.5 amperes, which 12 AWG copper (rated 20 amperes at the 60°C column used for most equipment terminations) satisfies with a small margin. The breaker protecting that circuit is the 30-ampere size the nameplate marks, which E3705.5.4 allows even though 12 AWG copper is otherwise limited to a 20-ampere breaker; a 35-ampere breaker would exceed the nameplate's maximum overcurrent protection value and is not permitted, even though the conductor itself might otherwise carry more current on a different circuit.

Water heaters and other fixed appliances

An electric water heater's disconnecting means follows the same general rule as any other permanently connected appliance: within sight of the water heater, or a breaker capable of being locked open (Table E4101.5). A technician replacing a heating element needs certainty that nobody two floors away can restore power by flipping a breaker back on, which is exactly the scenario a lockable breaker or an in-sight disconnect is built to prevent.

In the field

On a kitchen rehab with a new dishwasher, disposal, and range going in the same week, GCHS reads every nameplate before anything else. The nameplate tells the crew the circuit size, whether the branch breaker can double as the disconnect or whether a separate one is needed, what cord length and receptacle access the appliance's listing calls for, and whether the location adds a GFCI requirement on top of all of it. Skipping straight to "does it fit and does it turn on" is how a correctly wired but improperly disconnected appliance passes a walkthrough and fails an inspection.

Practice questions

1. A permanently connected appliance rated over 300 volt-amperes generally needs a disconnecting means that is:

  1. Within sight of the appliance, or capable of being locked in the open position
  2. Located inside the service panel only, even when the appliance is on a different floor of the dwelling
  3. Rated at least 60 amperes
  4. Optional if the appliance is hardwired

2. Under the code's definition, "within sight" of an appliance disconnect means:

  1. Anywhere in the same house
  2. Visible and not more than 50 feet from the equipment
  3. Within 100 feet regardless of visibility
  4. Within earshot of the equipment

3. A disposal's own marked unit switch may serve as one of its disconnecting means when:

  1. Disposals are exempt from disconnect requirements
  2. Unit switches are always lockable
  3. An additional individual switch or circuit breaker serves as the other required disconnecting means
  4. The appliance is fueled by gas rather than electricity, which exempts it from a separate branch-circuit disconnect

4. A cord-and-plug-connected household electric range's attachment plug and receptacle may serve as the disconnecting means when they are:

  1. Replaced with a twist-lock connector
  2. Located behind the range against the wall only, with no access from the front of the range or the room
  3. Rated at 15 amperes
  4. Provided with access, meaning reachable for operation and inspection

5. An inspector finds a garbage disposal's cord about 5 feet long, coiled beyond its allowed length, tucked under the sink near the drain trap. The correct disposition is:

  1. Cite it, because Table E4101.3 limits a disposal cord to 18 to 36 inches and excess cord under a sink is exposed to damage
  2. Approve it, since Table E4101.3 sets only a minimum cord length for disposals and a longer cord easily clears the drain trap
  3. Approve it if the disposal is plugged into a GFCI
  4. Approve it if the cord is 12 AWG

6. An inspector finds a dishwasher's cord-and-plug receptacle in the adjacent cabinet space, as required, but behind a permanently fastened panel that requires removing the dishwasher to reach. This is:

  1. Acceptable, since the cord reaches the receptacle
  2. Not acceptable, because the receptacle serving as the disconnect must remain accessible
  3. Acceptable if the circuit is GFCI protected
  4. Acceptable only in new construction, since existing kitchens are exempt from the accessibility rule

7. A new dryer circuit is being installed in a rehab addition. The equipment grounding conductor must be:

  1. Omitted if the dryer is gas-fired
  2. The same conductor as the neutral, as in a 3-wire circuit with the frame bonded to it
  3. A separate conductor, with the frame isolated from the neutral (4-wire circuit)
  4. Sized the same as the neutral only

8. An inspector finds an existing 3-wire dryer circuit in an occupied house being reused for a replacement dryer. The correct approach is:

  1. Require the circuit be rewired to 4-wire in every case, because the IRC prohibits 3-wire dryer circuits in both new and existing homes
  2. Bond the frame to a separate ground rod at the dryer
  3. Require a GFCI breaker in place of the equipment ground
  4. Recognize that an existing 3-wire circuit is not condemned by age alone, while any new circuit must be 4-wire

9. A condenser's nameplate reads minimum circuit ampacity 19.5 amperes and maximum overcurrent protection 30 amperes. Under E3702.11, the branch-circuit conductors must have an ampacity of at least:

  1. 19.5 amperes
  2. 15 amperes, the smallest standard branch-circuit breaker size
  3. 30 amperes, the maximum overcurrent protection value shown on the nameplate
  4. Whatever the installer chooses

10. A condenser's nameplate reads maximum overcurrent protection 30 amperes, and a 35-ampere breaker is installed to protect the circuit. This is:

  1. Acceptable, since larger breakers are always safer and the conductors are rated for more than 30 amperes
  2. Not acceptable, because it exceeds the nameplate's 30-ampere maximum overcurrent protection value
  3. Acceptable if the conductor is upsized to match
  4. Acceptable only for a heat pump

11. An inspector finds an air conditioning condenser's disconnect mounted on an access panel that must be removed to service the unit. This arrangement is a problem because:

  1. Access panels are never permitted outdoors
  2. It voids the condenser warranty and violates the listing requirement for weatherproof outdoor mounting locations
  3. Removing the panel to service the unit takes the disconnect out of sight exactly when it must be visible
  4. It requires a larger breaker

12. An electric water heater's disconnecting means must be:

  1. Inside the tank jacket
  2. At the utility meter
  3. Not required for water heaters
  4. Within sight of the water heater, or a breaker capable of being locked open

13. A rehab crew has just installed a new dishwasher, disposal, and range in one kitchen. The first thing to check on each appliance should be:

  1. The nameplate, since it sets the circuit size, disconnect option, cord provisions, and any added protection requirement
  2. The appliance color
  3. The cabinet dimensions
  4. The countertop material

14. Comparing an appliance's overcurrent protective device to its disconnecting means, the two serve:

  1. The identical function, so only one is ever required
  2. Different purposes: the overcurrent device protects the conductors, while the disconnect lets a person isolate the equipment for service
  3. No distinct purpose, since a circuit breaker used as the disconnect means a separate overcurrent device is no longer required in the circuit
  4. A purely cosmetic requirement

Glossary

Disconnecting means
A device or group of devices that isolates a circuit or piece of equipment from its source of supply.
Within sight
Visible and not more than 50 feet from the equipment it refers to; a specific, measured term, not a general sense of nearby.
Nameplate
The manufacturer's data plate on an appliance, showing at minimum its identification and its electrical rating in volts and amperes or watts.
Minimum circuit ampacity (MCA)
The smallest conductor ampacity the manufacturer allows for the branch circuit supplying a piece of HVAC equipment.
Maximum overcurrent protection (MOP)
The overcurrent device size and type marked on the equipment for protecting that same branch circuit.
Unit switch
A switch built into an appliance with a marked "off" position that disconnects all ungrounded conductors to the appliance.
Overcurrent protective device (OCPD)
A breaker or fuse sized to open the circuit before conductor damage from excess current, a separate job from disconnecting for service.
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