# Transformer sizing conductors and lights at park

#### augie47

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

#### Prototype1

##### Member
The transformer own by the power company and after the meter, it is own by the owners of the place. If that make sense.

#### Prototype1

##### Member
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 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.

P = I*E
1st circuit: 3521.2 W / 120 V = 29.34 A
2nd circuit: 1924.8 W / 120 V = 16.04 A
3rd circuit: 1544 W / 120 V = 12.87 A
29.34+16.04+12.87 = 58.25 A, and I can use 60 A panel.

Last edited:

#### augie47

##### Moderator
Staff member
Correct me if I am wrong:
You are adding a relative small load (8.4kw) to an existing 150kva customer owned transformer.
All the wiring is outside.

If that's the case, 240.21(C)(4) applies and you can add a M/B panel adequate for the load. A 60 panel would be more than adequate
(You can, of course, go larger if you want to allow for future loads)

#### Prototype1

##### Member
Yes, to my knowledge the transformer is only feeding the building. In the example drawing I attached. They adding a new conduit, conductors going to the new panel ( after I size it) and from the panel, the conduit/conductors go to the lights and etc. In the future, they will be adding more things on that panel, like 5hp motors, more lights, and etc.

#### Prototype1

##### Member
Till now, I understand that 60 Amp panel is good.
1st circuit: 3521.2 W / 120 V = 29.34 A
2nd circuit: 1924.8 W / 120 V = 16.04 A
3rd circuit: 1544 W / 120 V = 12.87 A

Because my lighting is continuous load,
should I do 29.34 * 1.25 = 36.675 A
16.04 * 1.25 = 20.05 A
12.87 * 1.25 = 16.0875 A

and go to Table 310.16, to size the conductors?

#### augie47

##### Moderator
Staff member
Unless you are already locked in on 120v fixtures I would suggest 208v fixtures. Reduces your current and helps on voltage drop.

#### Prototype1

##### Member
Here is the example drawing. The transformer is existing there and the panels, lights and conduit/conductors are still need to be size.

#### Attachments

• info lights.JPG
24.3 KB · Views: 3

#### Prototype1

##### Member
Unless you are already locked in on 120v fixtures I would suggest 208v fixtures. Reduces your current and helps on voltage drop.
Okay.
1st circuit: 3521.2 W / 208 V = 16.93 A
2nd circuit: 1924.8 W / 208 V = 9.25 A
3rd circuit: 1544 W / 208 V = 7.42 A

Because my lighting is continuous load,
should I do 16.93 * 1.25 = 21.1625 A
9.25 * 1.25 = 11.5625 A
7.42 * 1.25 = 9.27 A

There are very low amps. Table 310.16 does not show wire size for this low. Which other table?
and go to Table 310.16, to size the conductors?

#### augie47

##### Moderator
Staff member
see instant message

#### Attachments

• lights.png
33.4 KB · Views: 1
• info lights.JPG
24.3 KB · Views: 1