Site Lighting

[ctrane]

Can you use a 60Amp ( I used 60 because 20+20+20) 3 Pole Breaker, and run the three phases plus a ground out to site lighting and circuit as such: Please click on full size, because the thumbnail doesn't appear to show everything, and please excuse the drawing, I only had Paint to work with.

I am hoping that this is the proper circuiting to connect three separte one phase lighting in a delta connection.

 

[bob]

You are asking can you do this. Yes you can. But the load is not 60 amps,
its 20 amps per phase if that is what you are indicating in your post. If the load is continuous you will need a conductor with a capacity of 20 x 1.25 = 25 amps. # 10 with a 3 pole 30 amps breaker will do assuming that voltage drop is not a problem.

 

[ctrane]

First, thank you for the reply. Did my diagram correctly show the loads delta connected? Second, why did you say 3 pole 30a breaker? Thanks for the help.

 

[bob]

Second, why did you say 3 pole 30a breaker?

Because you are showing 3 phase conductors. You need a 3 phase breaker or 3 pole breaker.

 

[ctrane]

I did say 3 pole initially for the three phases, but I ask why you say 30A? I said 60A because that is 20 for each phase. Why do you say 30A?

 

[iwire]

A 3 pole 60 amp breaker is capable of providing 60 amps per phase, not 20.

 

[ctrane]

Thanks so much for clearing that up. Are the connections shown correct to wire 3 separate one phase loads into a delta connection?

 

[infinity]

After looking at your drawing it appears that your arrangement would require a minimum 3-pole 40 amp CB. As I understand it, your potential connected load is:

A-B=20 amps/phase
B-C=20 amps/phase
A-C=20 amps/phase

Total connected load:
A phase=40 amps
B phase=40 amps
C phase=40 amps

 

[RUWired]

ctrane, If you are connecting these 20a loads ab-bc-ca,they are in a delta configuration. Your actual load on each of the 3 phases will be 34.6 amps.In delta, line current = ipx1.73.Since this is site lighting,I would assume it will be on for more than 3 hrs.Your 34.6 amp load x 125%=43.25 amps.A minimum 45a breaker and a #6 thhn wire using 60 degree terminations will be required.
Rick

 

[ctrane]

Thanks so much for the reply. Let me ask you another question. It seems more feasible to me, from an engineering point of view, to run a 3 pole circuit our for site lighting and connect them in delta, than to run three separate 2 pole circuits to the same load. Immediatley, there is the savings of running half the wire count, downsizing the phase wire, and efficiency since you get root3 added power. Are there drawbacks to this arrangement that I am overlooking?

 

[infinity]

I don't see how your power consumption will differ using the single three phase configuration, versus 3 two-pole circuits.