I will try my best to answer this. I will first explain that there is a difference between LV, EV and Lux.
Light Value is a simplified figure of Lux and is an industry standard. Please refer to the table below:
EDIT: It seems I had this very wrong. I have updated it.
Camera manufactures generally use a light box at the value of 12 for adjustments. So, the light value for 12 is 12,000 Lux.
Lux (as quoted above) is a unit of measuring light, or luminance. Please refer to the table below:
Illuminance Surfaces illuminated by:
0.0001 lux Moonless, overcast night sky (starlight)
0.002 lux Moonless clear night sky with airglow
0.27–1.0 lux Full moon on a clear night
3.4 lux Dark limit of civil twilight under a clear sky
50 lux Family living room lights (Australia, 1998)
80 lux Office building hallway/toilet lighting
100 lux Very dark overcast day
320–500 lux Office lighting
400 lux Sunrise or sunset on a clear day.
1000 lux Overcast day; typical TV studio lighting
10000–25000 lux Full daylight (not direct sun)
32000–130000 lux Direct sunlight
Exposure Value is really Exposure compensation. If you change this value, you are not changing the Lux being shone into the camera. The only way to change the Lux is to change the lighting.
Above, you saw before that the Light Value and Lux are related. Now I'll go into more detail of the LV.
For a camera to be exposing correctly, it is said that it must have the following consistencies:
LV = 12 (or 10,240 Lux)
ISO = 100
Aperture = f5.6
Shutter = 1/125
For repairing and adjusting cameras, the light boxes are valued at LV and temperature. LV is just an industry standard to simplify the Lux value. If you want exact measurement, a lux meter would be your best bet.
While the above table is also a standard, it may vary camera to camera (probably not more than a stop. I haven't done enough testing, though). If you're trying to calculate the LV/Lux, it'll be best to look at the Lux table above.