Mike,

Here's some info on a similar unit up for auction at Ebay:
Quote
Pow-R-Safe C 2500 Electrical Tool Tester Set.

This model is a multi-amp that has an input of 120V, 50/60 Hz, Fuse Rating is 20, Short Circuit, Power Ground and On/Off Pilot.

** Power Cord NOT Included**

Pow-R-Safe Electrical Equipment Test Set Model C-2500 is a completely self-contained unit providing all necessary circuitry and indicators to automatically test electrical hazards and other faults. Unsafe conditions in the equipment under test are indicated by audible and visual signals which indicate the specific type of defect.

Model C-2500 provides these two key features:
** The 2-wire, double-insulated tool switch is provided to satisfy the ground circuit which is not present in these tools and permits faster, simpler testing by eliminating extra steps and additional test leads.

** The tool run test switch is provided to prevent double-insulated tools from running at the end of the test cycle. This permits power ground testing of the internal insulation through the metal drive shaft of the tool.

It also can be used to prevent tools from running at the end of the test cycle when it is not practical or safe to do so. Additionally, it can be used in a similar manner to test 3-wire tools with insulated housings.

Specifications:
Rating of device under test: 120V AC, 50/60 Hz, 1ø 20 amperes full load
Input: 120 volts, 50/60 Hz, 1ø
Operation: Fully automatic
Dimensions: 15 3/4 L x 8 H x 81/4 D (393.75 L x 200 H x 206.25 D mm)

Closeup Picture: http://wearepsls.com/Mrpowertech_Store/2006-04-01/Pow_R-Safe.2.jpg

[This message has been edited by Bill Addiss (edited 12-01-2006).]

Bill