Non-Dwelling Buildings Load Calculations- Part Three


In Article Non-Dwelling Buildings Load Calculations- Part One ", I introduced a List for ordinary Non-Dwelling Buildings Loads which was as follows: 

  1. Lighting loads,
  2. Receptacles Loads,
  3. Kitchen Loads,
  4. Heating, Ventilation and air conditioning Loads (Non-Coincident Loads),
  5. Motor Loads,
  6. Other Loads.


Again, but for above Non-Dwelling Buildings Loads, I will explain the following points:

  1. Where and how to distribute each type of load in a dwelling unit as per NEC code?
  2. How to calculate its Demand load for feeder and service sizing calculations?




Important!!!
All design Calculations for Non-dwelling Buildings will be as per NEC standard calculation method but I will explain design calculations as per NEC Optional calculation method only for the following Non-Dwelling buildings as permitted by NEC, Part IV. Optional Feeder and Service Load Calculations:

  1. Schools
  2. Existing Installations
  3. New Restaurants





I explained the Design Calculation for first type of Non-Dwelling Building loads which is Lighting loads in Article 
Non-Dwelling Buildings Load Calculations- Part One ".
Also, I explained part one of Design Calculation for second type; Receptacle loads for Non-Dwelling Buildings in Article " Non-Dwelling Buildings Load Calculations- Part Two ".

Today, I will explain the Design Calculation of Receptacle loads - second part for Non-Dwelling Building Loads which is Receptacle Loads. 



Second: Receptacle Loads – Part Two


1- Locations of General-use Receptacle Loads in Non-dwelling Buildings




Important!!!
In Non-dwelling buildings (commercial and industrial buildings), many 120-volt receptacles may be necessary to accommodate any devices that don’t have special electrical requirements (General-use).

But The NEC code doesn’t specify the quantity and location of General-use receptacles in Non-dwelling buildings, Unlike the dwelling buildings where the NEC code specifies the quantity and location of General-use receptacles as explained before in Article





Rule#1: Quantity and Location of General-use receptacles in Non-dwelling buildings – General Rule

Since, there is no receptacle placement provisions is specified by NEC code for Non-Dwelling Buildings, the following provisions can be used:


  • The “ 6 ft rule” which is the maximum distance to a receptacle measured horizontally along the walls in dwelling units will not applied here, while The maximum advised distance between receptacles (12 ft rule) is a helpful guideline for general office spaces.
  • No general-use receptacles are needed in commercial bathrooms, but if installed, it must be GFCI type.
  • The designer adds one receptacle for each restroom.
  • The designer adds one receptacle for approximately 20 ft of wall space in hallways and corridors (to accommodate cleaning equipments such as vacuums.
  • As per NEC section 210.63, one 120 volt receptacle within 25 ft of any heating, air conditioning or refrigeration equipment, which may include any roof mounted air conditioning equipment





Important!!!
The quantity and location of these General-use receptacles will ultimately depend on customer requirements, so we have two cases:

Case#1: If the final customer requirements are known during the design phase
Case#2: If the final customer requirements are not known





Rule#2: Quantity and Location of General-use receptacles in Non-dwelling buildings in Case#1

In this case, the following provisions will be done:


  • The designer customizes the quantity and location of general purpose receptacles to meet the customer’s specific needs.
  • The designer might meet directly with the customer to discuss any specific requirements and alter the design accordingly.
  • The practical locations of these receptacles will be based also on the permanent furniture layout of the building, space, or area under design.





Rule#3: Quantity and Location of General-use receptacles in Non-dwelling buildings in Case#2

In this case, the designer must strive to create a design that provides for the average user’s electrical needs and allows for flexibility for future additions and expansions. For each area inside the building, the minimum number of receptacle outlets should be determined by assuming there is no furniture in that area and the following provisions will be done:


  • The designer adheres to the NEC requirements for general purpose receptacles in dwelling buildings 210.52(A)(1) to provide a sufficient quantity of receptacles and meet any future needs.
  • For any other areas within the facility, the designer should consider how frequently the space is occupied and what is the primary usage of each space is to determine the proper quantity and placement of general use receptacle outlets.





Important!!!
In case#2, after getting the permanent furniture layout of the building, space, or area under designs, the practical locations of general-use receptacles can be adjusted on this time.






1.1 Special Case: Locations and Minimum Quantity of General-use Receptacle Loads in Guest Rooms, Guest Suites, Dormitories, and Similar Occupancies



Definitions:

Guest Room:
An accommodation combining living, sleeping, sanitary, and storage facilities within a compartment.

Guest Suite:
An accommodation with two or more contiguous rooms comprising a compartment, with or without doors between such rooms, that provides living, sleeping, sanitary, and storage facilities.





Rule#4: Receptacles Placement for Guest rooms or guest suites in hotels, motels, sleeping rooms in dormitories, and similar occupancies

Receptacles shall be installed such that no point measured horizontally along the floor line of any wall space is more than 1.8 m (6 ft) from a receptacle outlet.









Definition:
The wall space is a wall unbroken along the floor line by doorways, fireplaces, archways, and similar openings and may include two or more walls of a room (around corners), as illustrated in Exhibit 210.27. The Minimum length for a wall space is 2 ft.




Important!!!
The wall space behind the swing of a door is included in the measurement. This does not mean that the receptacle outlet has to be located in that space, only that the space is included in the wall-line measurement.




Rule#5: Minimum Number of Receptacles for Guest rooms or guest suites in hotels, motels, sleeping rooms in dormitories, and similar occupancies

As per 210.60(B), At least two receptacle outlets must be readily accessible without requiring the movement of furniture to access those receptacles.





Important!!!
Where receptacles are installed behind the bed, the receptacle shall be located to prevent the bed from contacting any attachment plug that may be installed or the receptacle shall be provided with a suitable guard. To reduce the risk of fire to bedding material, receptacles located behind beds must include guards if attachment plugs could contact the bed.




Rule#6: Bathroom Receptacles for Guest rooms or guest suites in hotels, motels, sleeping rooms in dormitories, and similar occupancies

As per NEC Section 210.52(D), at least one receptacle outlet shall be installed in bathrooms in one of the following locations:

Within 900 mm (3 ft) (36 inch) of the outside edge of each basin.
on the side or face of the basin cabinet not more than 300 mm (12 in.) below the basin countertop.

special cases for Rule#9 are as follows:


  1. If there is more than one basin, a receptacle outlet is required adjacent to each basin location.
  2. If the basins are in close proximity, one receptacle outlet installed between the two basins can be used to satisfy this requirement as shown in below image (top).




Rule#7: Guest rooms or guest suites provided with permanent provisions for cooking and countertop areas

Extended-stay hotels and motels are often equipped with permanent provisions for cooking and countertop areas and shall have receptacle outlets installed in accordance with all of the applicable rules in 210.52.

Note that, a portable microwave oven is not considered to be a permanently installed cooking appliance.







How to specify the required Type of general-use receptacles for each area?

1- Grounding type





As per NEC section 406.4, Receptacles installed on 15- and 20-ampere branch circuits shall be of the grounding type.



2- GFCI type





As per NEC section 210.8 (B), all 125-volt, single-phase, 15- and 20-ampere receptacles are GFCI for the following locations:

A) Bathrooms 


Some motel and hotel bathrooms have the basin located outside the door to the room containing the tub, toilet, or another basin.




Definition:
A bathroom is defined in Article 100 as “an area including a basin with one or more of the following: a toilet, a urinal, a tub, a shower, a bidet, or similar plumbing fixtures.”




Important!!!
As per NEC section 406.9(C), it is prohibited to install a receptacle within or directly over a bathtub or inside a shower stall even if the receptacles are installed in a weatherproof enclosure.




Important!!!
As per NEC section 210.11(C)(3), At least one 20-ampere branch circuit shall be provided to supply bathroom receptacle outlet(s). This circuit is permitted to supply the required receptacles in more than one bathroom as show in above image (bottom).




B) Kitchens

All 15- and 20-ampere, 125-volt kitchen receptacles in non-dwelling-type kitchens must be GFCI protected, whether or not the receptacle serves countertop areas.


Definition:
Kitchen: is an area with a sink and permanent facilities for food preparation and cooking.
Note that, A portable cooking appliance (e.g., cord-and-plug-connected microwave oven or hot plate) is not a permanent cooking facility.


Kitchens, meeting the Article 100 definition above, in restaurants, hotels, schools, churches, dining halls, and similar facilities are examples of the types of kitchens covered by this requirement.



C) Rooftops

As per NEC 210.63, a 125-volt, single-phase, 15- or 20-ampere-rated receptacle outlet shall be installed at an accessible location for the servicing of heating, air-conditioning, and refrigeration equipment.

The receptacle shall be located on the same level and within 7.5 m (25 ft) of the heating, air-conditioning, and refrigeration equipment. The receptacle outlet shall not be connected to the load side of the equipment disconnecting means.

This receptacle improves worker safety by eliminating the need to employ makeshift methods of obtaining 125-volt power for servicing and troubleshooting.

Exception for GFCI requirement for 210.63 receptacles is as follows:

  1. Receptacles that are not readily accessible and are supplied by a branch circuit dedicated to electric snow-melting, deicing, or pipeline and vessel heating equipment shall be permitted to be installed in accordance with 426.28 or 427.22, as applicable.



D) Outdoors

Other than the limited exclusions covered by the two exceptions to 210.8(B)(4), all 125-volt, single-phase, 15- and 20-ampere receptacles installed outdoors at commercial, institutional, and industrial occupancies are required to be provided with ground-fault circuit-interrupter protection.

The two exceptions to 210.8(B)(4) are as follows:

  1. Receptacles that are not readily accessible and are supplied by a branch circuit dedicated to electric snow-melting, deicing, or pipeline and vessel heating equipment shall be permitted to be installed in accordance with 426.28 or 427.22, as applicable.
  2. In industrial establishments only, where the conditions of maintenance and supervision ensure that only qualified personnel are involved, an assured equipment grounding conductor program as specified in 590.6(B) (2) shall be permitted for only those receptacle outlets used to supply equipment that would create a greater hazard if power is interrupted or having a design that is not compatible with GFCI protection.


Important!!!
Although commercial, institutional, and industrial occupancies are not required to have outdoor receptacle outlets installed for general use, there may be outdoor receptacle outlets installed to meet the requirement of 210.63 or at the discretion of the designer or owner.





E) Sinks

Where receptacles are installed within 1.8 m (6 ft) of the outside edge of the sink.

This requirement covers receptacles installed near sinks in lunchrooms, janitors’ closets, classrooms, and all other areas that are not covered by the bathroom and kitchen provisions of 210.8(B)(1) and (B)(2). 





Two exceptions to above are as follows:

  1. In industrial laboratories, receptacles used to supply equipment where removal of power would introduce a greater hazard shall be permitted to be installed without GFCI protection.
  2. For receptacles located in patient bed locations of general care or critical care areas of health care facilities other than those covered under 210.8(B)(1), GFCI protection shall not be required.


F) Indoor wet locations

G) Locker rooms with associated showering facilities

H) Garages, service bays, and similar areas where electrical diagnostic equipment, electrical hand tools, or portable lighting equipment are to be used



3- Tamper-Resistant type




  • NEC Section 406.12 requires listed tamper-resistant receptacles in all areas specified in 210.52 for dwelling units to increase the level of safety for children. Since guest rooms or guest suites in hotels and motels are also likely to be occupied by children, this section requires the same level of protection.
  • As per NEC 406.13, all non-locking-type, 125-volt, 15- and 20-ampere receptacles located in guest rooms and guest suites shall be listed tamper-resistant receptacles.
  • As per NEC 406.14 In all child care facilities, all non-locking-type, 125-volt, 15- and 20- ampere receptacles shall be listed tamper-resistant receptacles.




In the next article, I will continue explaining Receptacles load calculations for Non-Dwelling Buildings. Please, keep following.



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