AC Circuits

[roger]

The following was sent to me via PM so I am posting it here in a thread of it's own for discussion.

How are
Please explain and give me the answer following questions because this is very important for my work thank you very much (for non dwelling units)
1-Is this A/C (air conditions) loads continuous or non continuous loads?
2- Is electric space heating loads continuous or non continuous loads?
3- Is motors load continuous or non continuous loads?



4-if I make design of motor control center panel for air conditions loads and motors and delta/star starting is this needs to apply 440.22(b)(1) and 430.52 table for selecting over current protection device or the code have another solution for this case
4-if I have panel board contain 3 lighting circuits, 4 receptacles circuits, 6 A/C (air condition) circuits if I want to size the circuit breaker of panel and the conductor what is the suitable section for this
a-use 210.20 for circuit breaker sizing and 210.19 for for main conductor sizing
Or use
b-440.22(B)(1) for circuit breaker sizing and 430.34 for for main conductor sizing


Thanks

Roger

 

[cadpoint]

You have to remember to read the introductions of the Articles.

1. Note 424.22 (all), 440 is to address the type or style of HVAC motor, in this case this article helps to determine a Breaker Size.
2. Between one and two, you'd only use the larger of the two unless both are needed. Electric space heating is 424but bumps you over to 440 if other type.
3- If one goes to 430 -430.21 you protecting the branch circuit(s) to be not less than 125%, this might be your one of the possible continious duty aspects/thoughts. It just depends... Motor breaker can be up to 225% for a breaker!

Please explain and give me the answer following questions because this is very important for my work thank you very much (for non dwelling units)
1-Is this A/C (air conditions) loads continuous or non continuous loads?
2- Is electric space heating loads continuous or non continuous loads?
3- Is motors load continuous or non continuous loads?

Look at it this way, a breaker get's one through the motor start up and the wires are protected at 100% up to 125%. The motor settles down on Amp draw the wire still at 125% for indurance.
Wiring a motor is just different, you protect the motor with the breaker. While day in and day we'll protect the wire with the breaker! A HVAC motor as opposed to a motor are diffferent requirements thus address each accordingly.

4-if I make design of motor control center panel for air conditions loads and motors and delta/star starting is this needs to apply 440.22(b)(1) and 430.52 table for selecting over current protection device or the code have another solution for this case
4-if I have panel board contain 3 lighting circuits, 4 receptacles circuits, 6 A/C (air condition) circuits if I want to size the circuit breaker of panel and the conductor what is the suitable section for this
a-use 210.20 for circuit breaker sizing and 210.19 for for main conductor sizing
Or use
b-440.22(B)(1) for circuit breaker sizing and 430.34 for for main conductor sizing

4- 5. You have to go where the code tells you.

Reading 420 through say 440.31 just the main articles headers will do, there's just alot jammed in there.

Studing, Figure 430.1 is a really a good thing.
Welcome to the party, I think...

 

[George Stolz]

1-Is this A/C (air conditions) loads continuous or non continuous loads?

It is a motor, so every component of the system is determined a little differently. The "continuous load" concept is kind of lost on the process. In general, the math is already done for us on the nameplate, so to be honest, I'd spend all night reading Article 440 to try to cobble an answer together.

2- Is electric space heating loads continuous or non continuous loads?

See 424.3(B).

3- Is motors load continuous or non continuous loads?

Again, motors are weird. I would recommend reading through all of Article 430 and determine exactly what it is you want to know - do you want to know how large the conductors need to be for that one circuit? Or what the load of the motor is to the service?

4-if I have panel board contain 3 lighting circuits, 4 receptacles circuits, 6 A/C (air condition) circuits if I want to size the circuit breaker of panel and the conductor what is the suitable section for this

A load calculation per Article 220, paying attention to 220.18(A).