8. Install the front AC outlet-mounting plate screws (stabilizer mounting screws) into the mounting
plate and through the mounting holes in the rack. Securely tighten the screws.
9. Place the star washer onto the ground lug of the rear AC outlet-mounting plate.
10. Place the lug on the short end of the ground cable onto the ground lug.
11. Place a ground lug nut onto the ground lug and securely tighten it.
12. Connect the Y-shaped end of the ground cable to the rack frame, either near the center in the rear of
the rack or to the ground bus bar at the rear of the rack.
13. Position the rear AC outlet-mounting plate onto the rack frame.
14. Install the rear AC outlet-mounting plate screws (stabilizer mounting screws) into the mounting plate
and through the mounting holes in the rack. Securely tighten the screws.
For instructions about how to install front or rear AC outlet-mounting plates with AC outlets, see
“Installing the AC outlet-mounting plates with AC outlets” on page 48.
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
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.
About this task
Before plugging the rack into the AC power source, complete the following checks on the AC power
source:
Procedure
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, complete the following
steps:
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” on page 52
are not correct, 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 innite 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 innite resistance between the phase pins. This is a check
for a wiring short.
6. Turn on the branch circuit breaker.
52
Power Systems: Racks and rack features
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