Megger 235303 Tool and Appliance Tester

The Megger 235303 Tool and Appliance Tester combines, in one portable instrument, the three most frequently specified electrical safety tests for tools and appliances. In conformance to UL and ANSI test requirements, the instrument performs test of ground continuity, leakage current, and electrical insulation. It also checks the nameplate current rating of the device.

Poorly maintained electrical tools can become a safety hazard and cause injury to personnel. Testing electrical tools on a regular basis is not only safe practice against costly repairs, but may even reduce liability. Applications for this handy instrument include in-plant OSHA safety surveys and production line, tool room, and repair shop safety checks.

To check the integrity of the ground circuit between tool and plug, the Tool and Appliance Tester applies a 25- ampere test current to the ground circuit. If the ground circuit resistance exceeds the 0.10-ohm failure threshold, a safety interlock prevents further testing. A bypass switch is provided to allow testing of two-wire and double-insulated devices.

The leakage test measures the current that would result from the ground conductor being accidentally severed; that is the current to which the operator would be subjected if providing a path to ground at normal line voltage. A switch is provided to select testing at normal or reverse polarity. Measurements from 0 to 10 mA are indicated on a large, 3.5-in. (89 mm) analog meter with sensitivity greater than 0.01 mA. To ensure the accuracy of the meter, a calibration check can be initiated at the push of a button.

The insulation Breakdown (High-Pot) Test measures current through insulation at high voltage to detect weak spots in the insulation that may cause failure in the future. Test voltage up to 3000 volts ac may be applied, with the leakage current trip level adjustable from 0.3 to 12 mA by a front-panel control knob. Visual and audible alarms alert the operation to insulation failure.

The Tool and Appliance Tester also provides an operation check to verify the nameplate current rating of the tool and to determine if maintenance is required. Measurements up to 15 amperes are indicated.