PEC Chapter 4 - Air-conditioning

True

Disconnecting means shall be within sight of equipment, readily accessible and may be on or within the equipment. The disconnecting means shall not be located on panels that are designed to allow access to the air conditioning or refrigeration equipment or to obscure the equipment nameplates.

True

The enclosures of room air conditioners shall be connected to the equipment grounding conductor.

True

A controller shall be marked with the manufacturer's name, trademark, or symbol; identifying designation; voltage; phase; full-load and locked-rotor current (or horsepower) rating; and other data as may be needed to properly indicate the motor-compressor for which it is suitable.

manufacturer's name, trademark, or symbol; identifying designation; phase; voltage; and frequency

A hermetic refrigerant motor-compressor shall be provided with a nameplate that shall indicate the _______________. The rated-load current in amperes of the motor-compressor shall be marked by the equipment manufacturer on either or both the motor-compressor nameplate and the nameplate of the equipment in which the motor-compressor is used.

True

A hermetic refrigerant motor-compressor, or equipment containing such a compressor, having a protection system that is approved for use with the motor-compressor that it protects and that permits continuous current in excess of the specified percentage of 156 of the rated current shall also be marked with a branch-circuit selection current. This marking shall be provided by the equipment manufacturer and shall be on the nameplate(s) where the rated-load current(s) appears.

unfused motor circuit switch

A listed ________________-, without fuseholders, having horsepower greater than that of the tabulated one, shall be permitted if less than 115 percent of the specified current

250 volts

A room air conditioner (with or without provisions for heating) shall be considered as an ac appliance of the air-cooled window, console, or in-wall type that is installed in the conditioned room and that incorporates a hermetic refrigerant motor-compressor(s). Rated not over _____ single phase, and the equipment shall be permitted to be cord-and attachment-plug-connected. Does not cover 3-phase over _____.

40 amperes, 250 volts

A room air conditioner shall be considered as a single motor unit in determining its branch-circuit requirements where all the following conditions are met: - It is cord-and attachment-plug-connected. - Its rating is not more than _____ and ______, single phase. - Total rated-load current is shown on the room air-conditioner nameplate rather than individual motor currents. - The rating of the branch-circuit short-circuit and ground-fault protective device does not exceed the ampacity of the branch-circuit conductors or the rating of the receptacle, whichever is less.

True

An air-conditioning or refrigerating system shall be considered to be a single machine

1.8 m (6 ft)

An attachment plug and receptacle or cord connector shall be permitted to serve as the disconnecting means for a single-phase room air conditioner rated 250 volts or less if (1) the manual controls on the room air conditioner are readily accessible and located within _____ of the floor, or (2) an approved manually operable disconnecting means is installed in a readily accessible location within sight from the room air conditioner.

Article 4.40

Article number for air-Conditioning and Refrigirating EquipmentAir-Conditioning and Refrigirating Equipment

125, 72

Branch-circuit conductors supplying a single motor-compressor shall have an ampacity of ___ percent of the motor-compressor rated-load current or the branch circuit selection current. If wye-start delta-run, the conductors between controller and motor are permitted to be ___ percent of current

True

Conductors supplying a motor-compressor load in addition to other load(s) shall have an ampacity sufficient for the other load(s) plus the required ampacity for the motor-compressor load, for a single motor-compressor Where the circuitry is interlocked so as to prevent simultaneous operation of the motor-compressor(s) and all other loads connected, the conductor size shall be determined from the largest size required for the motor-compressor(s) and other loads to be operated at a given time.

True

Conductors supplying one or more motor-compressor(s) with or without an additional motor load(s) shall have an ampacity not less than the sum of each of the following: - The sum of the rated-load or branch-circuit selection current, whichever is greater, of all motor-compressor(s) - The sum of the full-load current rating of all other motors - 25 percent of the highest motor-compressor or motor full load current in the group Where the circuitry is interlocked so as to prevent the starting and running of a second motor-compressor or group of motor-compressors, the conductor size shall be determined from the largest motor-compressor or group of motor-compressors that is to be operated at a given time.

True

Equipment that starts and operates on a 15- or 20-ampere 120-volt, or 15-ampere 208- or 240-volt single-phase branch circuit, shall be permitted to be protected by the 15- or 20-ampere overcurrent device protecting the branch circuit, but if the maximum branch-circuit short-circuit and ground-fault protective device rating marked on the equipment is less than these values, the circuit protective device shall not exceed the value marked on the equipment nameplate.

True

Every disconnecting means in the refrigerant motor-compressor circuit between the point of attachment to the feeder and the point of connection to the refrigerant motor-compressor shall comply with the requirements or motor-compressor.

True

For a hermetic refrigerant motor-compressor, the rated-load current marked on the nameplate of the equipment in which the motor-compressor is employed shall be used in determining the rating or ampacity of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and the separate motor overload protection. Where no rated-load current is shown on the equipment nameplate, the rated-load current shown on the compressor nameplate shall be used.

accessible only, not required to be readily accessible

For cord-and-plug connected equipment such as room air conditioners, household refrigerators and freezers, drinking water coolers, and beverage dispensers, a separable connector or an attachment plug and receptacle shall be permitted to serve as the disconnecting means

True

For multimotor equipment employing a shaded-pole or permanent split-capacitor-type fan or blower motor, the full-load current for such motor marked on the nameplate of the equipment in which the fan or blower motor is employed shall be used instead of the horsepower rating to determine the ampacity or rating of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and the separate overload protection. This marking on the equipment nameplate shall not be less than the current marked on the fan or blower motor nameplate.

six

For small motor-compressors not having the locked-rotor current marked on the nameplate, or for small motors not covered by motor tables, the locked-rotor current shall be assumed to be _____ times the rated-load current.

True

If motor-compressor is not the largest for short circuit and ground fault protection, shall not exceed a value equal to the sum of the rated-load current or branch-circuit selection current, whichever is greater, rating(s) for the motor-compressor(s) plus the value specified in 4.30.4.3(C)(4) where other motor loads are supplied, or the value specified in 2.40.1.4 where only nonmotor loads are supplied in addition to the motor-compressor(s).

True

If the motor-compressor is the largest for protection of short circuit and ground fault, add the individual permitted rating, the one with 175 and 225 to the rated-load current or branch circuit selection current of the other loads.

True

Motor-Compressor Controller. The continuous-duty full-load current rating and locked-rotor current rating not less than the nameplate rated-load current or branch-circuit selection current greater than the sum of compressors to be controlled.

True

Motor-Compressor and Branch-Circuit Overload Protection - Protection for excessive heating or failure to start - A protective system, furnished or specified and approved for use with the motor-compressor that it protects on the basis that it will prevent dangerous overheating of the motor-compressor due to overload and failure to start. If the current-interrupting device is separate from the motor-compressor and its control circuit is operated by a protective device that is not integral with the current-interrupting device, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motor-compressor.

True

Motor-Compressor and Branch-Circuit Overload Protection - Protection for excessive heating or failure to start - A thermal protector integral with the motor-compressor, approved for use with the motor-compressor that it protects on the basis that it will prevent dangerous overheating of the motor-compressor due to overload and failure to start. If the current-interrupting device is separate from the motor-compressor and its control circuit is operated by a protective device integral with the motor-compressor, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motor-compressor.

140

Motor-Compressor and Branch-Circuit Overload Protection - Protection for excessive heating or failure to start - Separate overload relay that trips not more than ____ percent of the rated load current

125

Motor-Compressor and Branch-Circuit Overload Protection - Protection for excessive heating or failure to start - Time-delay fuse or Inverse Time Circuit breaker which shall also be permitted as short circuit or ground fault protection rated not exceeding ____ percent of the load. The equipment or the motor-compressor shall be marked with this maximum branch-circuit fuse or inverse time circuit breaker rating.

True

Multimotor and combination-load equipment shall be provided with a visible nameplate marked with the maker's name, the rating in volts, frequency and number of phases, minimum supply circuit conductor ampacity, the maximum rating of the branch-circuit short-circuit and ground-fault protective device, and the short-circuit current rating of the motor controllers or industrial control panel.

True

Multimotor and combination-load equipment that is suitable under the provisions of this article for connection to a single 15- or 20-ampere, 120-volt, or a 15-ampere, 208- or 240-volt, single-phase branch circuit shall be permitted to be marked as a single load.

True

Multimotor and combination-load equipment used in one-and two-family dwellings or cord-and-attachment-plug-connected equipment shall not be required to be marked with a short-circuit current rating.

True

Overload protection for motor-compressors and equipment that are cord-and attachment-plug-connected and used on 15- or 20-ampere 120-volt, or 15-ampere 208- or 240-volt, single-phase branch circuits the overload protection is any of the previously mentioned, both the controller and the motor overload protective device shall be identified for installation with the short-circuit and ground-fault protective device for the branch circuit to which the equipment is connected, the rating of the attachment plug and receptacle or cord connector shall not exceed 20 amperes at 125 volts or 15 amperes at 250 volts. The short-circuit and ground-fault protective device protecting the branch circuit shall have sufficient time delay to permit the motor-compressor and other motors to start and accelerate their loads. Same for those that are not cord and plug, just remove the rating restrictions.

True

Overload relays and other devices for motor overload protection that are not capable of opening short circuits shall be protected by fuses or inverse time circuit breakers, since sometimes fuse and CB are used overload and protection, unless identified for group installation or for part-winding motors and marked to indicate the maximum size of fuse or inverse time circuit breaker by which they shall be protected. The fuse or inverse time circuit breaker size marking shall be permitted on the nameplate of the equipment in which the overload relay or other overload device is used.

175, 225, 15 amperes

Protect the branch-circuit conductors against overcurrent due to short circuits and ground faults. The motor-compressor branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the motor. A protective device having a rating or setting not exceeding ___ percent of the motor-compressor rated-load current or branch-circuit selection current, whichever is greater, shall be permitted, provided that, where the protection specified is not sufficient for the starting current of the motor, the rating or setting shall be permitted to be increased but shall not exceed ____ percent of the motor rated-load current or branch-circuit selection current, whichever is greater. Shall not be less than ________

115

Rating of Disconnecting Means for single hermetic - For ampere rating, at least ____ percent of the nameplate rated-load current of branch circuit selection current, whichever is greater - For equivalent horsepower rating of the switch, select horsepower from the table using full-load, selection current, or locked-rotor current, then that's it.

True

The ampacity of the conductors supplying multimotor and combination-load equipment shall not be less than the minimum circuit ampacity marked on the equipment

Rated-Load Current

The current of a hermetic refrigerant motor-compressor resulting when it is operated at the rated load, rated voltage, and rated frequency of the equipment it serves.

True

The disconnecting means required here is capable of disconnecting air-conditioning and refrigerating equipment, including motor-compressors and controllers.

True

The highest rated (largest) motor shall be considered to be the motor that has the highest rated-load current. Where two or more motors have the same highest rated-load current, only one of them shall be considered as the highest rated (largest) motor.

True

The individual motor circuit conductors of wye-start, delta-run connected motor-compressors carry 58 percent of the rated load current. The multiplier of 72 percent is obtained by multiplying 58 percent by 1.25.

more than 9 amperes at 115 volts, or more than 4.5 amperes at 230 volts

The locked-rotor current of each single-phase motor-compressor having a rated-load current of _________ and each polyphase motor-compressor shall be marked on the motor-compressor nameplate.

True

The minimum supply circuit conductor ampacity and the maximum rating of the branch-circuit short-circuit and ground-fault protective device shall not be required to be marked on a room air conditioner

156

The motor-compressor controller(s), the disconnecting means, and the branch-circuit conductors shall be protected against overcurrent due to motor overload and failure to start by one of the following means - An overload relay - A thermal protector that will not permit a continuous current in excess of _____ percent of the marked rated-load current or branch-circuit selection current - A fuse or inverse time circuit breaker - A protective system that will not permit a continuous current in excess of ____ percent of the marked rated-load current or branch-circuit selection current

True

The nameplate marking of cord-and-plug-connected equipment rated not greater than 250 volts, single-phase, such as household refrigerators and freezers, drinking water coolers, and beverage dispensers, shall be used in determining the branch-circuit requirements, and each unit shall be considered as a single motor unless the nameplate is marked otherwise.

50

The total marked rating of a cord-and attachment-plug-connected room air conditioner shall not exceed ____ percent of the rating of a branch circuit where lighting outlets, other appliances, or general-use receptacles are also supplied. Where the circuitry is interlocked to prevent simultaneous operation of the room air conditioner and energization of other outlets on the same branch circuit, a cord-and attachment-plug-connected room air conditioner shall not exceed 80 percent of the branch-circuit rating.

80 percent

The total marked rating of a cord-and attachment-plug-connected room air conditioner shall not exceed _______ of the rating of a branch circuit where no other loads are supplied.

Branch-Circuit Selection Current

The value in amperes to be used instead of the rated-load current in determining the ratings of motor branch-circuit conductors, disconnecting means, controllers, and branch-circuit short-circuit and ground-fault protective devices wherever the running overload protective device permits a sustained current greater than the specified percentage of the rated-load current. Its value will always be equal to or greater than the marked rated-load current.

3.0 m (10 ft), 1.8 m (6 ft)

Where a flexible cord is used to supply a room air conditioner, the length of such cord shall not exceed _________ for a nominal, 120-volt rating or ______ for a nominal, 208- or 240-volt rating.

thermally protected, thermally protected system

Where a thermal protector is used, the motor-compressor nameplate or the equipment nameplate shall be marked with the words "_______________." Where a protective system complying is used and is furnished with the equipment, the equipment nameplate shall be marked with the words, "___________________." Where a protective system is specified, the equipment nameplate shall be appropriately marked.

Where part of the concurrent load is a resistance load and the disconnecting means is a switch rated in horsepower and amperes, the switch used shall be permitted to have a horsepower rating not less than the combined load to the motor-compressor(s) and other motor(s) at the locked-rotor condition, if the ampere rating of the switch is not less than this locked-rotor load plus the resistance load. You can only consider motors in horsepower as long as current is okay.

Where combined load of two or more hermetic refrigerant with other motors or loads may be simultaneous in a single disconnecting means, the rating shall be 1. For horsepower rating, simply add all currents, including resistive loads, in rated load and locked rotor condition, the combined current shall be considered as a single motor. In case that two motors may not operate at the same time, the higher combination of locked-rotor is the selected one. 2. For ampere rating, 115 the sum of the currents.

True

Where equipment is installed outdoors on a roof, an equipment grounding conductor of the wire type shall be installed in outdoor portions of metallic raceway systems that use compression-type fittings.

True

Where the disconnecting means provided in accordance with 4.30.9.2(A) is lockable and the refrigerating or air-conditioning equipment is essential to an industrial process in a facility with written safety procedures, and where the conditions of maintenance and supervision ensure that only qualified persons service the equipment, a disconnecting means within sight from the equipment shall not be required.

True

Where the rated-load or locked-rotor current as determined above would indicate a disconnecting means rated in excess of 100 hp, 4.30.9.9(E) shall apply.