Extech Instruments LT505 User manual

USER MANUAL
LUX/FC Light Meter
Model LT505
Additional User Manual Translations available at www.extech.com

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Introduction
Thank you for selecting the Extech Model LT505 LUX/FC Light Meter. The LT505 measures light
from fluorescent, metal halide, high-pressure sodium and incandescent sources in lux and foot-
candles. This device 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 and
translations of this User Manual, Product Updates, Product Registration, and Customer Support.
Features
Measure intensity of light (illuminance) in lux or foot-candles
Light sensor with cosine correction
Low battery indicator
Data hold
Auto-ranging
Auto Power OFF (APO)
Light weight, compact, design
Safety
Please read the entire User Manual before operating this device. Use the meter only as specified
and do not attempt to service or open the meter housing.
Do not use the meter in the presence of explosive gas or vapor
Do not expose the meter to extremes in temperature or to high humidity
Please dispose of batteries and meter responsibly and in accordance with all applicable
laws and regulations
Do not allow children to handle the meter or the protective cover
Meter and LCD Description
1. Light Sensor (protective sensor cover not shown)
2. LCD
3. LUX-FC button
4. CAL-ZERO button
5. Power button
6. Data Hold button
7. MAX-MIN Record button
Note: Battery compartment and Tripod mount on rear of
meter

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1. Battery status
2. Auto Power OFF (APO)
3. Data Hold
4. Maximum reading
5. Average reading
6. Minimum reading
7. Measurement
8. Units of measure
9. Calibration (ZERO)
Operation
Meter Power
Power the meter by long pressing the button. The meter will begin displaying light intensity
readings. If the LCD does not switch on, check the batteries located in the rear battery
compartment. Short press power button to turn OFF the meter.
Zero Calibrate the Sensor
1. Place the protective cover over the sensor and press the button to power on the meter.
2. If the display does not read ‘0.0’ short press the button.
3. The CAL icon will appear in the secondary display.
4. The CAL icon will switch OFF when the calibration has been completed.
5. If the protective cap is not covering the sensor when the button is pressed, the LCD
display will read “CAP”. In this case, please cover the sensor with the cap and restart this
procedure.
6. It is recommended that the meter be switched off and then on again when repeating the
zero calibration function.
Taking Measurements
Remove the sensor cover and aim the sensor toward the light source. View the measurement on
the meter’s display.
Selecting the Unit of Measure
Press the button to toggle the units between Lux and Foot-candles. The units will indicate in
the display.
Data Hold
Short press the button to freeze or unfreeze a reading on the display.

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MAX/MIN Button
The meter records the maximum, minimum, and average readings as described below:
1. Short press the button and the meter will begin tracking the maximum, average, and
minimum measurements. The MAX icon will display at the top of the LCD indicating the
meter is now showing the maximum reading. The reading will not change until a higher
reading is registered.
2. Short press the button again to switch from MAX to AVG, where the meter will show
the average measurement value. The AVG icon will display in the LCD indicating the meter
is now showing the average reading.
3. Short press the button again to change the mode from AVG to MIN, where the meter
will show the minimum measurement value. The MIN icon will display in the LCD indicating
the meter is now showing the minimum reading.
4. Short press the button to step through MAX-AVG-MIN readings.
5. To exit this mode, long press the button. The MAX/AVG/MIN display icons will switch
off, and the meter will return to normal operating mode.
Auto Power OFF (APO)
In order to conserve battery life, the meter will automatically shut off after approximately 12
minutes of inactivity. The icon will appear in the display when APO is enabled.
To turn APO on or off, with the meter powered ON, long press the button. The icon will
appear in the upper LCD when APO is enabled and disappear when APO is disabled.
Measurement Considerations and User Tips
For maximum accuracy allow the light being measured to fall directly on the sensor as
perpendicular as possible with a minimal angle of incidence.
When the meter is not in use, please keep the protective cap over the light sensor. This will
prolong the life of the sensor.
When the meter is to be stored for long periods, please remove the batteries and store them
separately. Batteries can leak and cause damage to the meter’s components.
Avoid areas of high temperature and humidity when using this instrument.

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Maintenance
Battery Replacement
1. Power OFF the meter.
2. Press the button that secures the battery compartment at the back of the meter while
sliding the battery compartment cover off in a downward motion.
3. Replace the two (2) ‘AAA’batteries observing correct polarity.
4. Re-assemble the meter before use.
Safety: Please dispose of batteries responsibly; never dispose of batteries in a fire, batteries may
explode or leak. If the meter is not to be used for 60 days or more, remove the battery and store
separately.
Never dispose of used batteries or rechargeable batteries in household waste.
As consumers, users are legally required to take used batteries to appropriate collection
sites, the retail store where the batteries were purchased, or wherever batteries are
sold.
Disposal: Do not dispose of this instrument in household waste. The user is obligated to
take end-of-life devices to a designated collection point for the disposal of electrical and
electronic equipment.
Cleaning and Storage
Periodically wipe the case with a damp cloth and mild detergent; do not use abrasives or
solvents.

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Specifications
Display
9999 count LCD
Sampling rate 2.5 times per second
Light sensor
Silicone photodiode with cosine correction filter
Measurement Units
LUX and FC (Foot candles)
Lighting source types
Fluorescent, metal halide, high-pressure sodium, and
incandescent
Input Overload Display
‘OL’
Tripod mount
On back of meter
Power
2 x 1.5V AAA batteries
Low battery indicator included
Automatic power off
After approx. 12 minutes of inactivity
Operating Temp/Humidity
5°C to 40°C (40°F to 104°F); <80%RH Max
Operating Altitude
2000 meters (7000ft) maximum
Storage Temp/Humidity
-10°C to 60°C (14°F to 140°F); <70%RH Max
Dimensions/Weight
133 x 48 x 23mm (5.3 x 1.9 x 0.9”) /250g (8.8oz)
Safety
For indoor use only. EMC: EN61326-1 (2006), IEC 61000-
4-2 (2008, IEC 61000-4-3 (2006) + (2007); Pollution
Degree 2.

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Note: All ranges calibrated to a standard incandescent lamp at color temperature of 2856°K
Electrical Specifications (23±5°C)
Lux (autorange)
Unit
Range
Resolution
Accuracy
Lux
999.9
0.1
±3%rdg + 3 dgts
9 999
1
±3%rdg +10 dgts
99 990
10
400 000
100
Foot-candle (autorange)
Unit
Range
Resolution
Accuracy
fc
99.99
0.01
±3%rdg + 3 dgts
999.9
0.1
±3%rdg +10 dgts
9 999
1
40 000
10

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Appendices
Typical Light Levels (1 Fc = 10.76 Lux)
Lux
Foot
Candles
Lux
Foot
Candles
Factories
Home
20-75
2-7
Emergency Stairs,
Warehouse
100-150
10-15
Washing
75-150
7-15
Exit/Entrance Passages
150-200
15-20
Recreational Activities
150-300
15-30
Packing Work
200-300
20-30
Drawing Room, Table
300-750
30-75
Visual Work: Production
Line
300-500
30-50
Makeup
750-1,500
75-150
Typesetting: Inspection
Work
500-1,500
50-150
Reading, Study
1,500-3,000
150-300
Electronic Assembly,
Drafting
1,000-2,000
100-200
Sewing
Office
Restaurant
75-100
7-10
Indoor Emergency Stairs
75-150
7-15
Corridor Stairs
100-200
10-20
Corridor Stairs
150-300
15-30
Entrance,
Wash Room
200-750
20-75
Conference,
Reception Room
300-750
30-75
Cooking Room, Dining Table
750-1,500
75-150
Clerical Work
750-1,500
75-150
Show Window
1,500-2,000
150-2000
Typing, Drafting
Store
Hospital
75-150
7-15
Indoors
30-75
3-7
Emergency Stairs
150-200
15-20
Corridor/Stairs
75-100
7-10
Stairs
200-300
20-30
Reception
100-150
10-15
Sick Room, Warehouse
300-500
30-50
Display Stand
150-200
15-20
Waiting Room
500-750
50-75
Elevator
200-750
20-75
Medical Exam Room
750-1,500
75-150
Show Window,
Packing Table
750-1,500
75-150
Operating Room
1,500-3,000
150-300
Storefront, Show Window
5,000-10,000
500-1000
Eye Inspection
Spectral Sensitivity
Peak sensitivity wavelength: 550nm;
Deviation from comparative luminosity
standard: JIS standard C1609-1993.
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RELATIVE SENSITIVITY (%)
WAVELENGTH (nm)
LT505