Question 1

What is the difference between lux and foot-candles?

Accepted Answer

Both measure illuminance, the amount of light landing on a surface. One lux is one lumen per square metre; one foot-candle is one lumen per square foot, which works out at about 10.76 lux. US lighting specifications are usually written in foot-candles. Seven of the thirteen meters here switch between the two units. The LX-100F and LX-100F-CC read foot-candles only, and the LX-100, LX-101A and their -CC versions read lux only.

Question 2

How many foot-candles does OSHA require?

Accepted Answer

OSHA 29 CFR 1926.56 Table D-3 sets minimum illumination for construction work at 5 foot-candles for general construction area lighting, 3 foot-candles for general construction areas such as concrete placement, excavation and waste areas, access ways, active storage areas, loading platforms, refueling and field maintenance areas, 10 foot-candles for general construction plant and shops, and 30 foot-candles for first aid stations, infirmaries and offices.

Question 3

Do I need a calibration certificate on a light meter?

Accepted Answer

If the reading goes into a compliance record or a report a third party relies on, yes. Six of the thirteen light meters here ship with one: LX-100-CC at $179, LX-113S-CC at $189, LX-100F-CC at $199, LX-101A-CC at $209, LX-1128-SD-CC at $249.90 and LX-1108-CC at $279.

Question 4

Which light meter has the widest measuring range?

Accepted Answer

The LX-1108 at $189 and the LX-1108-CC at $279 read 0 to 400,000 lux or 0 to 40,000 foot-candles at plus or minus 3 percent. Both have four light-type settings for tungsten, fluorescent, mercury and sodium sources, and both read white LED.

Question 5

Which light meter records readings?

Accepted Answer

The LX-1128SD at $219.90 and the LX-1128-SD-CC at $249.90 log to an SD card of 1 GB to 16 GB and connect to a computer over RS232 or USB. The SD card is not included. Both auto-range across 2,000, 20,000 and 100,000 lux at plus or minus 4 percent plus 2 digits.

Question 6

Why use a light meter with a separate sensor probe?

Accepted Answer

A probe on a lead sits at the measurement point while you read the display from a comfortable position, which matters when the fixture is overhead or the surface is awkward. The LX-101A, LX-113S and LX-1128SD all use a separate sensor probe.

Paranormal Research Instruments by Gary Galka · Professional Test Meters by DAS Distribution

Instrument-grade light measurement