This Article is about why the Fluke-88V is not able to measure 120V AC voltage.
The Fluke-88V is different from all the other digital multimeters. Instead of having the Auto Ranging feature active as a default when you turn it on it uses the Manual range. When you use the AC voltage mode it uses the 6.000V range and if you try to measure 120V AC the results will show OL because the 6.000V range is not able to measure above 6.000V. You have two choices to change the meters ranges. You can push the Range button two times to go from the 6.000V range to the 60.00V range to the 600.0V range. The 120V level needs to use the 600.0V range or you will still get the OL response. The other choice is to push and hold the Range button, and it will switch to the Auto Range.
Below are some pictures of the Fluke-88V showing the meter in the AC volts mode and going from the 6.000V range to the other ranges and the final results.