USER GUIDE Digital Light Meter Model LT300
Introduction Congratulations on your purchase of the Extech LT300 Digital Light Meter. The LT300 measures light level (illuminance) to 400,000 Lux (40,000 Fc). The LT300 offers a backlit display, MAX/MIN, Data Hold, Relative, Peak, and Reset features. This instrument is shipped fully tested and calibrated and, with proper use, will provide years of reliable service. Please visit our website (www.extech.com) to check for the latest version of this User Guide, Product Updates, and Customer Support.
Operation Light sensor 1. The light sensor is permanently attached to the meter by the coiled cable. 2. Remove the protective cap by unsnapping it to expose the white domed light sensor. When the sensor’s protective cap is removed, the white domed light sensor lens will begin to capture light. Replace the cap when the meter is not in use. Turn Power ON or OFF Press the button to turn power on or off. If the display does not switch on, check that the 9V battery is installed and is fresh.
Peak Hold The Peak Hold feature allows the meter to captures light pulses that rise or fall down to 10µs. 1. Press and hold the PEAK button until CAL appears in the display. 2. Momentarily press the PEAK button. The ‘PMAX’ icon will appear on the LCD. The meter will then measure and display any light pulses. The display will hold the results until a higher pulse appears. 3. Press the PEAK button again to display the “PMIN” values. 4.
Maintenance Cleaning and storage 1. The white plastic sensor dome should be cleaned with a damp cloth when necessary. Use only a mild soap if needed. Do not use solvents, abrasives, or harsh detergents to clean the dome. 2. Store the meter in an area with moderate temperature and humidity (refer to the operating and storage range in the ‘Specifications’ section). Battery Replacement When the battery power begins to fail the low battery symbol “ ”will appear on the LCD.
Specifications Ranges and Resolution Accuracy Lux 40.00, 400.0, 4000, 40.00k, 400.0kLux ± (5% Rdg + 0.5% Full Scale) Foot candle (Fc) 40.00, 400.0, 4000, 40.00kFc ± (5% Rdg + 0.5% Full Scale) General Specifications Display Multi‐function 3‐3/4 (3999) digit LCD with Bargraph indicator Over range indication LCD displays ‘OL’ Spectral response CIE photopic (CIE human eye response curve) Spectral accuracy CIE V function (f1 6%) Measurement Repeatability ±2% Temperature coefficient o ±0.
Appendix Typical Light Levels Lux Foot Candles 20‐75 75‐150 2‐7 7‐15 150‐300 15‐30 300‐750 750‐1,500 1,500‐3,000 30‐75 75‐150 150‐300 75‐100 100‐200 7‐10 10‐20 200‐750 20‐75 750‐1,500 1,500‐2,000 75‐150 150‐200 200‐300 Lux Foot Candles Factories Emergency Stairs, Warehouse Exit/Entrance Passages 100‐150 150‐200 10‐15 15‐20 Packing Work 200‐300 20‐30 300‐500 500‐1,500 1,000‐2,000 30‐50 50‐150 100‐200 75‐150 150‐300 7‐15 15‐30 300‐750 30‐75 750‐1,500 75‐150 30‐75 75‐100 100‐150 3
