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39. Connect the power distribution system as described in "Connecting the power distribution system."
40. After the rack is bolted down and you are going to attach a front electrical outlet, go to "Attaching
the front or back ac electrical outlet" on page 16.
41. If you are not going to attach a front electrical outlet and you are installing rack doors, go to
Chapter 5, "Attaching the rack doors," on page 105.
Connecting the power distribution system
You can use a power distribution system to monitor the individual power loads of the devices that are
plugged into it. Use the procedure in this section to connect this system.
To connect a Power Distribution Unit, see Chapter 11, "Power distribution unit plus," on page 127.
Checking the ac outlets
To help ensure safety and reliable operation, you should check the ac outlets. Use the procedure in this
section to perform this task.
Before you begin, ensure that you have a multimeter to check voltages and an appropriately approved
ground-impedance tester to test the grounding resistances.
Note: Use only an appropriately approved ground-impedance tester to test the grounding resistances. Do
not use a multimeter to measure grounding resistance.
Before plugging the rack into the ac power source, complete the following checks on the ac power source.
1. Turn off the branch circuit breaker for the ac power outlet that the rack will plug into. To the circuit
breaker switch, attach tag S229-0237, which reads "Do Not Operate."
Note: All measurements are made with the receptacle faceplate in the usual installed position.
2. Some receptacles are enclosed in metal housings. For this type of receptacle, do the following:
a. Using a multimeter, check for less than 1 volt from the receptacle case to any grounded metal
structure in the building, such as a raised-floor metal structure, water pipe, building steel, or
similar structure.
b. Using a multimeter, check for less than 1 volt from the receptacle ground pin to a grounded point
in the building.
Note: If the receptacle case or faceplate is painted, be sure the probe tip penetrates the paint and
makes good electrical contact with the metal.
c. Using a multimeter, check the resistance from the receptacle ground pin to the receptacle case.
Check resistance from the ground pin to the building ground. The readings should be less than 1.0
ohm, which indicates the presence of a continuous grounding conductor.
3. If any of the checks made in step 2 are not correct, ask the customer to remove the power from the
branch circuit and make the wiring corrections. Recheck the receptacle after the wiring is corrected.
4. Using a ground-impedance tester, check for infinite resistance between the ground pin of the
receptacle and each of the phase pins. This is a check for a wiring short to ground or a wiring
reversal.
5. Using a ground-impedance tester, check for infinite resistance between the phase pins. This is a check
for a wiring short.
6. Turn on the branch circuit breaker.
7. Using a multimeter, measure for the appropriate voltages between phases. If no voltage is present on
the receptacle case or grounded pin, the receptacle is safe to touch.
8. Using a multimeter, verify that the voltage at the ac outlet is correct.
Chapter 2. Installing the rack
15
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