Grouping

[Kiraed]

The system is 120/208V 3P, 4W and I need to install 28 dedicated outlets 120V, 20A, 1P, 60Hz. Can I group dedicated circuit in a conduit? If I can put them in EMT conduit, Is it 56 wires for the 28 outlet?

 

[LarryFine]

The system is 120/208V 3P, 4W and I need to install 28 dedicated outlets 120V, 20A, 1P, 60Hz. Can I group dedicated circuit in a conduit? If I can put them in EMT conduit, Is it 56 wires for the 28 outlet?

Depends on what "dedicated" means: One receptacle per circuit or no multi-wire circuits.

If shared neutrals are okay, you can run three circuits using four conductors.

The quantity of current-carrying conductors per conduit will affect derating.

 

[Kiraed]

No sharing neutrals, one receptacle per circuits.

there are 28 receptacles so correct me here if I understand this Right.

Per receptacle there are 1 Hot + 1 Neutral in single phase. So for the 28 receptacle, we have 56 current carrying conductors. Next, Using #12awg 90 degree. 30A x 0.50 gives us 15A. So 3 sets 1” EMT conduit is what I got.

 

[infinity]

No sharing neutrals, one receptacle per circuits.

there are 28 receptacles so correct me here if I understand this Right.

Per receptacle there are 1 Hot + 1 Neutral in single phase. So for the 28 receptacle, we have 56 current carrying conductors. Next, Using #12awg 90 degree. 30A x 0.50 gives us 15A. So 3 sets 1” EMT conduit is what I got.

Yes that would work if you want 15 amp circuits but you said 20 amp in the OP.

 

[Kiraed]

Yes I did in my calculations I assumed if it is continuous Load 20Ax0.80 = 16A

so I thought It’s not bad to lose 1A. Please correct me if I am wrong or if there is another options that is better.

 

[LarryFine]

Best is a panel close to the loads; in the middle minimizes run lengths, and reduces the number of circuits each way.

 

[infinity]

Yes I did in my calculations I assumed if it is continuous Load 20Ax0.80 = 16A

so I thought It’s not bad to lose 1A. Please correct me if I am wrong or if there is another options that is better.

Just use #10 AWG conductors. (40*50%=20amps)

 

[Kiraed]

Awesome. This helps a lot. Thank you very much everyone. I really appreciate the help.

 

[augie47]

What did I miss ? No shared neutrals = 56 current carrying conductors = 35% derating ??

 

[Kiraed]

There are 56 current carrying conductors. No neutral shared. So 3 sets of 1” EMT conduit, 50% Derating

 

[augie47]

Got it. I missed the (3) runs of 1".. was looking at the 56 ccc.
Reading in not my forte'

 

[Kiraed]

For curiosity, how would you install this if you want to share the neutral? What are the rules and method?

 

[augie47]

It would depend on the nature of your load. If the major portion of the load is non-linear then no changes but if the load is linear then the neutrals would not be considered current carrying where all three phases were present.
Migh be able to get more circuits per conduit but you would have a trade off of simultaneous trip on your breaker.

 

[Kiraed]

It would depend on the nature of your load. If the major portion of the load is non-linear then no changes but if the load is linear then the neutrals would not be considered current carrying where all three phases were present.
Migh be able to get more circuits per conduit but you would have a trade off of simultaneous trip on your breaker.

Hmm I see. Thanks