Re: Post: Sizing conductors, conduit for lights and Transformer? Need help on my work

[Prototype1]

I have a transformer 150KVA Primary - 12470 GRDY /7200 V and Secondary 208Y/120 V. ( I understand that GRDY is grounded wye(Y) primary configuration with 12,470V between each phase and the neutral, and 7200 v between any two phases.) (208Y/120 V is three phase, four wire secondary configuration, 208 v between each phase and 120 v between any phase and the neutral.)

I attached example drawing of where the transformer, panel, and lights will be like.
68 Lights:
Pickleball court – Total Watts – 3,584 (8 lights)
Tennis – Total Watts – 2,406 (6 lights)
Trail Lights – Total Watts = 1170 Watts (26 Poles lights)
Bollards – Total Watts = 760 Watts (20 Bollards lights)
Disk Lights – Total Watts = 480 Watts (8 lights)
Total watts: 8400 Watts
3 circuits from the panel board. 1 going to the pickleball court and plaza lights. 1 going to the tennis court. 1 for the trail lights and bollards.

So, to get VA from watts. I have to do equation Watts / Power Factor = VA????
How do I size conductors for lights?

Transformer OCPD conditions:
If it is supervised location for the transformer than you are going to select next lower standard size: if it is (primary voltage > 600V and secondary voltage > 600V). But if the (secondary voltage <= 600V), select next Higher standard size, fuse/circuit breaker.)

Conditions: Primary side of transformer
Overcurrent protection at primary side (Primary > 600V) : Rating of primary fuse at point A = 300 % of primary. FLC or next standard size or Rating of primary circuit breaker at point A = 600%. FLC or next standard size. - Unsupervised

• Rating of Primary Circuit Beaker, so next higher standard size. - Unsupervised

Calculation: Primary side
(Primary > 600V): Rating of primary circuit breaker at point A = 600%

I did Full load current: 150000 VA / 12470 V*1.732 = 6.945 A
Rating of primary Circuit Breaker = 6*6.945 = 41.67 A, and select next standard size 45 A Circuit Breaker. from table 240.6(A)

conductor sizing: 6.945 A * 1.25 = 8.68 A
Table 310.16, 75°C" **Table 315.60**: AWG ????

In previous post @david luchini said: "The smallest 15kV conductor size is #2. See 315.60, not 310.16. A #2 conductor has an ampacity well above the required 6.945A."
I did not know which table 315.60 to see but I am assuming table 315.60(C)(3), as it has 5001 to 1500 volts ampacity section.

@david luchini mention that: "transformer primary is 12,470V. You will need a conductor that has 15,000V (15kV) insulation."
@david luchini mention: "6.945A is the minimum required ampacity for the transformer feeder. You need a conductor that has an ampacity that is 6.945 or greater."
"#2 awg is the minimum size conductor for 15kV, and #2 has an ampacity much higher than 6.945."

Conditions: Secondary side of transformer
Overcurrent protection at secondary side (Secondary Voltage <= 600V)

• Rating of Sec. Fuse / Circuit Breaker at Point B= 125% of Sec. Full Load Current or Next higher Standard size. -Unsupervised

Overcurrent Protection at Secondary Side (Secondary Voltage >600V):

• Rating of Secondary. Fuse at Point B= 250% of Sec. Full Load Current or Next higher Standard size. -Unsupervised
• Rating of Secondary. Circuit Breaker at Point B= 300% of Sec. Full Load Current. -Unsupervised

Calculation: Secondary side
Overcurrent protection at secondary side (Secondary Voltage <= 600V):

I did Full load current: 150000 VA / 208V*1.732 = 416.73 A
Rating of primary Fuse/Circuit Breaker: 416.37 A * 1.25 = 520.46 A
520.46 A, so next standard size of circuit breaker = 600A Circuit breaker from table 240.6(A)

conductor sizing: 416.37 A * 1.25 = 520.46 A, conductors should have ampacity of at least 600 A because of circuit beaker is 600A
Table 310.16, 75°C: 600A: so, I select (2) 350 kcmil conductors in parallel
Table **250.102(C)(1) ** for grounding: #2 G AWG

Is this how you size your conductors for transformer?

Any help will be appreciate.

 

[tom baker]

P=ExI
Convert watts into amps.
Use the wire ampacity table in 310 to find wire size at 75 deg C.
Add up amps per phase and size panel
And lighting is a continuous load so use 1.25 on sizing conductors

 

[Prototype1]

Pickleball court – Total Watts – 3,584 (8 lights) - 448 watts each light
Tennis – Total Watts – 2,406 (6 lights) - 401 watts each light
Trail Lights – Total Watts = 1170 Watts (26 Poles lights) - 45 watts each light
Bollards – Total Watts = 760 Watts (20 Bollards lights) - 38 watts each light
Disk Lights – Total Watts = 480 Watts (8 lights) - 60 watts each each light

3 circuits from the panel board. 1 going to the pickleball court and plaza lights. 1 going to the tennis court. 1 for the trail lights and bollards.

1st circuit:
Total wattage for the 1st circuit:
3584 watts + 480 watts = 4064 Watts

Apply the 80% continuous load factor.
4064 watts * 0.8 = 3251.2 watts

# of lights: 3251.2 watts / (448 watts/light + 60 watts/light) ~ 6.57 lights

Rounded down: Approximately 6 Pickleball lights and 6 plaza lights.


2nd circuit:
Total wattage for the 2nd circuit:
2406 watts

Apply the 80% continuous load factor.
2406 watts * 0.8 = 1924.8 watts

# of lights:1924.8 watts / (401 watts/light) ~ 4.80 lights
Rounded down: Approximately 4 tennis lights.



3rd circuit:
Total wattage for the 3rd circuit:
1170 watts + 760 watts = 1930 Watts

Apply the 80% continuous load factor.
1930 watts * 0.8 = 1544 watts

# of lights: 1544 watts / (45 watts/light + 38 watts/light) ~ 20.96 lights

Rounded down: Approximately 20 lights (combining Trail lights and Bollard lights). We have total 46 lights trail + bollard lights.

 

[augie47]

currently under discussion in previous thread

Transformer sizing conductors and lights at park

That makes more sense....... explains why such a large transformer..... Is this transformer a Power Company transformer or customer owned ?

forums.mikeholt.com