Making your selection The Ultra Series Power Wedge® 1118 Power Pack Power Conditioners Power Link Power Cords FAQ Get Our Catalog		Using a ground tester to check the electrical ground on the isolated outlets of a Power Wedge Ultra will result in an open ground reading or an indeterminate reading. This is normal. It is due to the of inability of most ground testers to properly measure an isolation transformer. Many ground testing devices will have a warning that they will not provide proper readings in these circumstances. All outlets on both the Ultra Wedge and Power Pack series maintain the electrical ground from the wall outlet.