Case study: Graton Casino and Resort

Backup power design for a high-performance building is required, and offers many benefits.


Graton Casino and Resort in Rohnert Park, Calif., uses three 1,500 kW/1,875 kVA, 480 V 3-phase parallel generators as a robust emergency/optional standby system (see Figures 2, 3, and 4). The generators are located outside of the building and are equipped with pad-mounted transformers to step up the generator output voltage from 480 to 2,160 V.

Table 2: Maximum demand-load table

Graton Casino and Resort


Maximum demand load




Entire property


4,392 kVA at 0.85 power factor


Expected load


Maximum base-load total


4,392 kVA




+ 20% contingency


879 kVA


For unforeseen future load growth


Total load


5,270 kVA or 141 amps at 21.6 kV 3-phase




Source: FEA Consulting Engineers

The priority loads include:

A. Priority 1 (emergency and legally required standby power).

1. Loads will be picked up by generators upon loss of utility power within 10 seconds.

2. Loads include:

a. Fire pumps.
b. Fire sprinkler air compressors.
c. Fire alarm.
d. Egress lighting.
e. Elevator cab lighting.
f. Elevator room cooling.
g. Tower guestroom toilet exhaust.
h. Tower supply fan.
i. Tower obstruction lighting.
j. Water-treatment plant.

B. Priority 2 (business critical/optional standby power).

1. Second set of loads picked up by generators upon loss of utility power within 60 seconds.

2. Loads include:

a. Select central plant equipment.
b. Boilers and water heaters along with associated pumps.
c. Booster pumps.
d. Air handler units.
e. Information technology cold room.
f. Surveillance cold room.
g. Telecommunication rooms.
h. Cooling for cold rooms.
i. Cooling for electrical rooms that contain optional standby equipment.
j. Slots.
k. Kitchen walk-in coolers and freezers.
l. Select lighting in BOH areas.
m. Lighting over gaming tables and at the cage.
n. Select site lighting.
o. Power for exterior cameras.

C. Priority 3 (normal power).

1. Third set of loads picked up by generators upon loss of power on a load-permissive basis.

2. Loads include:

a. Remaining central plant equipment.
b. High-limit area.
c. Event center.
d. Food court and restaurants.

D. Priority 4 (normal power).

1. Fourth set of loads picked up by generators upon loss of power on a load-permissive basis.

2. Loads include:

a. Select bars and restaurants.
b. Event-center kitchen.
c. Pool area and spa.

Michael Villalba is a designer with FEA Consulting Engineers. He previously worked for NV5. He has 3 years of experience working on projects such as convention centers, casinos, hotels, and photovoltaic farms.


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