Step 3. Checking Customer Outlets
Note: For a translation of the following notices, see System Unit Safety Information, Order Number
CAUTION:
Do not touch the receptacle or the receptacle faceplate with anything other than your test probes before you have met the requirement in step 8.
1.Have the customer locate and turn off the branch circuit CB (circuit breaker). (Attach tag
Note: All measurements are made with the receptacle faceplate in its normal installed position.
2.Some receptacles are enclosed in metal housings. On receptacles of this type, perform the following steps:
a.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.Check for less than 1 volt from 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.Check the resistance from ground pin of the receptacle to the receptacle case. Check resistance from ground pin to building ground. The reading should be less than 1.0 ohm, which indicates the presence of a continuous grounding conductor.
3.If any of the three checks made in step 2 are not correct, ask the customer to remove the power from the branch circuit and make the wiring corrections; then check the receptacle again.
Note: Do not use the digital multimeter to measure grounding resistance.
4.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.Check for infinite resistance between phase pins. This is a check for a wiring short.
CAUTION:
If the reading is other than infinity, do not proceed. Have the customer make necessary wiring corrections before continuing. Do not turn on the branch circuit CB until all the above steps are satisfactorily completed.
6.Have the customer turn on the branch circuit CB. Measure for appropriate voltages between phases. If no voltage is present on the receptacle case or grounded pin, the receptacle is safe to touch.
7.With an appropriate meter, verify that the voltage at the outlet is correct.
8.Verify that the grounding impedance is correct by using the ECOS 1020, 1023, B7106, C7106, or an appropriately approved ground impedance tester.
Note: Do not use the
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