Need help with this question; Branch Circuit Requirements

[trobbins313]

I am studying for my state licence and got this home work question; I am not sure how to answer or if this question has all the information.

Branch Circuit Requirements;
For Multioutlet Assembly

Max. Branch Circuit Load (Volt-Amps) ______________?

Outlet Limitation (Maximum) ______________?

OCPD Rating __________________________________?

Wire Size A.W.G. ______________________________?

NEC Code Reference ____________________________?


The way I went about answering it is, I assumed 120V & 20A circuit.
For Max. Branch Circuit Load (VA); 120V x 20A=2400VA
2400x80% = 1920VA

Outlet Limitation (Maximum); 1920VA?180VA=10.7. Is the answer 10.7 or it's 180VA per 5FT x 10.7 which gives me 52.5 FT as the answer?

OCPD Rating (Amps) 20A

Wire Size A.W.G. #12

NEC Code Reference 220.14(H)(1)


Thank you.

Tim

 

[Girl Engineer]

You don't know whether they are likely or unlikey to be used simultaniously and how long the assembly is.

 

[ToolHound]

2011 Code:

Chapter 2 Wiring and Protection
ARTICLE 220 Branch-Circuit, Feeder, and Service Calculations
II. Branch-Circuit Load Calculations

220.14 Other Loads — All Occupancies.

In all occupancies, the minimum load for each outlet for general-use receptacles and outlets not used for general illumination shall not be less than that calculated in 220.14(A) through (L), the loads shown being based on nominal branch-circuit voltages.

(H) Fixed Multioutlet Assemblies. Fixed multioutlet assemblies used in other than dwelling units or the guest rooms or guest suites of hotels or motels shall be calculated in accordance with (H)(1) or (H)(2). For the purposes of this section, the calculation shall be permitted to be based on the portion that contains receptacle outlets.

(1)

Where appliances are unlikely to be used simultaneously, each 1.5 m (5 ft) or fraction thereof of each separate and continuous length shall be considered as one outlet of not less than 180 volt-amperes.

(2)

Where appliances are likely to be used simultaneously, each 300 mm (1 ft) or fraction thereof shall be considered as an outlet of not less than 180 volt-amperes.

Related Handbook commentary:
Section 220.14 covers two conditions of use for fixed multioutlet assemblies, which are common in commercial and industrial locations. The first area of use is light use, which means that not all the cord-connected equipment is expected to be used at the same time, as defined in 220.14(H)(1). An example of light use is a workbench area where one worker uses one electrical tool at a time. The second area of use is heavy use, which is characterized by all the cord-connected equipment generally operating at the same time, as defined in 220.14(H)(2). An example of heavy use is a retail outlet displaying television sets, where most, if not all, sets are operating simultaneously.

As shown in Exhibit 220.2, the requirement of 220.14(H)(1) states that each 5 ft of a fixed multioutlet assembly must be considered as one outlet rated 180 volt-amperes. The requirement of 220.14(H)(2) states that where appliances are likely to be used simultaneously, each foot of multioutlet assembly is to be considered as one outlet rated 180 volt-amperes.


Below image is...Exhibit 220.2 The requirements of 220.14(H)(1) and (H)(2) as applied to fixed multioutlet assemblies.

 

[ToolHound]

I am studying for my state licence and got this home work....

Outlet Limitation (Maximum) ______________?

Thank you.
Tim

..


(Table 210.24 sez regarding 'permissable load' see 210.23(A). See the below 210.23(A)(1) subsection, which may be applicable to part of the question.)

210.23 Permissible Loads. In no case shall the load exceed the branch-circuit ampere rating. An individual branch circuit shall be permitted to supply any load for which it is rated. A branch circuit supplying two or more outlets or receptacles shall supply only the loads specified according to its size as specified in 210.23(A) through (D) and as summarized in 210.24 and Table 210.24.

(A) 15- and 20-Ampere Branch Circuits. A 15- or 20-ampere branch circuit shall be permitted to supply lighting units or other utilization equipment, or a combination of both, and shall comply with 210.23(A)(1) and (A)(2).

Exception: The small-appliance branch circuits, laundry branch circuits, and bathroom branch circuits required in a dwelling unit
(s) by 210.11(C)(1), (C)(2), and (C)(3) shall supply only the receptacle outlets specified in that section.

(1) Cord-and-Plug-Connected Equipment Not Fastened in Place. The rating of any one cord-and-plug-connected utilization equipment not fastened in place shall not exceed 80 percent of the branch-circuit ampere rating.

Also, 210.21(B)(2)&(3) sez:

210.21 Outlet Devices. Outlet devices shall have an ampere rating that is not less than the load to be served and shall comply with 210.21(A) and (B).

(B) Receptacles.

(2) Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord-and-plug-connected load in excess of the maximum specified in Table 210.21(B)(2).

Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle

Circuit Rating (Amperes)​ ​	Receptacle Rating (Amperes)​ ​	Maximum Load (Amperes)​ ​
15 or 20​ ​	15​ ​	12​ ​
20​ ​	20​ ​	16​ ​
30​ ​	30​ ​	24​ ​

(3) Receptacle Ratings. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or, where rated higher than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.

Exception No. 1: Receptacles for one or more cord-and-plug-connected arc welders shall be permitted to have ampere ratings not less than the minimum branch-circuit conductor ampacity permitted by 630.11(A) or (B), as applicable for arc welders.

Exception No. 2: The ampere rating of a receptacle installed for electric discharge lighting shall be permitted to be based on 410.62(C).


Related Handbook commentary:

A single receptacle installed on an individual branch circuit must have an ampere rating not less than that of the branch circuit. For example, a single receptacle on a 20-ampere individual branch circuit must be rated at 20 amperes in accordance with 210.21(B)(1); however, two or more 15-ampere single receptacles or a 15-ampere duplex receptacle are permitted on a 20-ampere branch circuit in accordance with 210.21(B)(3). This requirement does not apply to specific types of cord-and-plug-connected arc welders.

Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits

Circuit Rating (Amperes)​ ​	Receptacle Rating (Amperes)​ ​
15​ ​	Not over 15​ ​
20​ ​	15 or 20​ ​
30​ ​	30​ ​
40​ ​	40 or 50​ ​
50​ ​	50​ ​

Also, 210.19(A)(2) sez:

(2) Branch Circuits with More than One Receptacle. Conductors of branch circuits supplying more than one receptacle for cord-and-plug-connected portable loads shall have an ampacity of not less than the rating of the branch circuit.

Related Handbook commentary sez:
Because the loading of branch-circuit conductors that supply receptacles for cord-and-plug-connected portable loads is unpredictable, the circuit conductors are required to have an ampacity that is not less than the rating of the branch circuit. According to 210.3, the rating of the branch circuit is actually the rating of the overcurrent device.

 

[ToolHound]

I am studying for my state licence and got this home work question; I am not sure how to answer or if this question has all the information.

Branch Circuit Requirements;
For Multioutlet Assembly

Max. Branch Circuit Load (Volt-Amps) ______________?


The way I went about answering it is, I assumed 120V & 20A circuit.
For Max. Branch Circuit Load (VA); 120V x 20A=2400VA
2400x80% = 1920VA

Thank you.
Tim

The original post lacks specification whether the outlets will be used simultaneously, so why not go for 180 VA PER FOOT in accordance with the 220.14(H)(2).

You seem to be allowing for a load that is a continuous load. 210.19(A)(1) provides that conductors shall have an allowable ampacity not less than 125% of the continuous load plus 100% of the noncontinuous load. You have already factored that in.

 

[trobbins313]

Branch Circuit Requirements

Branch Circuit Requirements

The original post lacks specification whether the outlets will be used simultaneously, so why not go for 180 VA PER FOOT in accordance with the 220.14(H)(2).

You seem to be allowing for a load that is a continuous load. 210.19(A)(1) provides that conductors shall have an allowable ampacity not less than 125% of the continuous load plus 100% of the noncontinuous load. You have already factored that in.

Thank you so much ToolHound for the information. This info will help a lot.