Number of Outlets vs Overall Branch circuit Loads

[aelec84]

Hello Forum,
Can you pls help demystify this?

Per NEC 13 outlets are permitted to be connected on a 20A branch circuit (almost 2400VA). But I have seen always load is limited to 16A/1920 VA in panel schedules (10 outlets). Where is the discrepancy?

Thank you.

 

[infinity]

What type of occupancy? Are these commercial buildings?

 

[roger]

If you answer Infinity you might get your answer.

 

[LarryFine]

Where is the discrepancy?

Two points to ponder:

1. There's a difference between load calcs and actual wiring.

2. Receptacles do not use power.

 

[aelec84]

What type of occupancy? Are these commercial buildings?

Correct commercial buildings.

 

[infinity]

Correct commercial buildings.

Not sure why they would limit the load to 16 amps. How do they know the actual load?

 

[aelec84]

Not sure why they would limit the load to 16 amps. How do they know the actual load?

I researched some more. Do you think its coming from 210.21 (B)(2) and 210.23(A)?

 

[infinity]

I researched some more. Do you think its coming from 210.21 (B)(2) and 210.23(A)?

These are multi-receptacle circuits so I don't see where it would be required to calculate using 16 amp instead of 20 as in Mike's example. Where are you seeing the 16 amp number being used?

 

[aelec84]

These are multi-receptacle circuits so I don't see where it would be required to calculate using 16 amp instead of 20 as in Mike's example. Where are you seeing the 16 amp number being used?

Table 210.21(b)(2)

 

[suemarkp]

I could see someone treating those receptacle loads as continuous, thereby giving an 80% derate. I think this would be uncommon unless these serve a bunch of cubicle desks with a light, computer, monitor, etc that is on all day long. If these are general use circuits, I wouldn't expect the load to be continuous.

The 210.21(B)(2) limit is an 80% load limit at one receptacle, not the entire circuit.

 

[don_resqcapt19]

Table 210.21(b)(2)

That only says a single receptacle of a 20 amp multi-receptacle circuit shall not supply a cord-and-plug connected load exceeding 16 amps.