Link to various NEC calculators and Look-Up Tables:
http://www.electrician2.com/calculators/elcal.html .
From Mike Wood, of Mike Wood Consulting:
lumens/LUMENS = (VOLTS/volts)^3.4
life/LIFE = (VOLTS/volts)^13 (I.e., reduce the volts to 90% and the life increases by 393%!)
EFFICIENCY/efficiency = (VOLTS/volts)^1.9
watts/WATTS = (volts/VOLTS)^1.6
(not 'squared' as you would get with a fixed resistance)
coltemp/COLTEMP = (volts/VOLTS)^0.42
See
OSRAM SYLVANIA:Sylvania Automotive Lighting Catalog:
Link to an Excel workbook containing most of the above formulae.
See also Ushio's online calculator at
Lamp Life Calculator- Support.
Copied from this post by ship.
Contents
[hide][top]LIGHT OUTPUT CALCULATIONS
A dinner candle provides about 12 lumens. A 60-watt Soft White incandescent lamp provides 840 lumens.
- Foot-candles = candela / distance in feet * distance in feet
- Foot-candles = Lux / 10.764 = lumens/sq. meter
- 1 fc=1/10.764 lux
- Foot-candles * 10.764 = lumens/sq. meter = lux
- Lumens/sq. ft. * 1 = foot-candles; (1fc=1 lumen/ft²)
- Lumens/sq. ft. * 10.764 = lumens/sq. meter
- Lumens * 0.07958 = spherical candle power
- Lumens = Mean Spherical Candlepower x 12.57
- Lux * 0.0929 = foot-candles
- Lux = candela / (distance in meters * distance in meters)
- Lambert * 0.3183 = candela/sq. cm (candela per sq. cm), Lambert * (1/pi) = candles/sq. cm
- Lambert * 295.720 = candela/ sq. ft. (candela per sq. ft.)
- Lambert * 1 = lumens/sq. cm
- Illuminance (lx) = E = Luminous flux falling on area (lm) ÷ Illuminated area (m²)
- Illuminance (lx) = E = Luminous intensity (cd) ÷ (distance in meters (m))²
- Luminance (cd/m²) = L = Luminous intensidy (cd) ÷ viewed luminous area (M²)
- Luminous efficacy (lm/w) = h = Generated luminous flux (lm) ÷ Electrical power consumed (w)
- Efficacy=F(lu)/P(w)
- F=Luminous Flux
- P=Electrical Power (wattage), in watts
[hide][top]LIGHT BEAM CALCULATIONS:
See
Conventional Photometrics_v7.zip for a down-loadable MS Excel workbook containing most popular fixtures.
- Beam diameter = distance * (2 * tan (beam angle in degrees / 2))
- Throw distance = Square root ( (horizontal dist. * horizontal dist.) + (vertical dist. * vertical dist.) )
- Inverse Square Law: E(fc)=I(cd)/D(ft)². E(fc)=F(lm)/A(ft)²
- A=Area in square feet
- D=Distance in feet
- E=Illumination in footcandles
- F=Luminous Flux in Lumens
- I=Luminous intensity (Candlepower) in footcandles
Mired Shift Value = (1,000,000/d) - (1,000,000/a); d=Desired Color Temperature (no units), a=Actual Color Temperature (no units)
[hide][top]Fixture Lens Conversion Guide:
For a two-lens system: EFL= (f1*f2)/(f1+f2-d), where EFL=Effective Focal Length, f1=Focal Length of Lens1, f2=Focal Length of Lens2, d=Distance between Lenses.
- 50° - 3.5Q5 / 360Q-4.5x6.5 (45°)
- 40° - 3.5Q6 / 360Q-6x9 (37°)
- 30° - 3.5Q8 / 360Q-6x12 (27°)
- 20° - 3.5Q10 / 360Q-6x16 (17°)
- 10° / 12° - 3.5Q12 / 360Q-6x22 [single lens] (9.5°)
- 5° - None
- 8x8 (20°)
- 8x10 (16°)
- 8x16 (6°)
- 1Kw PAR64:
- ACL (GE 4552-28V, 250W)- Beam: 7°x8°
- ACL (GE 4559-28V, 600W)- Beam: 11°x12°
- VNSP (FFN), CP60 - Beam: 6° x 12° Field: 10° x 24°
- NSP (FFP), CP61 - Beam: 7° x 14° Field: 14° x 26°
- MFL (FFR), CP62 - Beam: 12° x 24° Field: 21° x 44°
- WFL (FFS), CP95 - Beam: 24° x 48° Field: 45° x 71°
- Power = Voltage * Current (Watts = Volts * Amps)
- P(w)=V(v)xI(a)
- P=Electrical Power (Wattage) in watts
- V=Voltage (EMF), in volts
- I=Electrical Current(Amperage), in amps
- Current = Power / Voltage (Amps = Watts / Volts)
- RMS Volts = 0.707 * Peak Volts RMS Volts = 1.11 * Average Volts
- Ohm’s Law: V(v)=I(a) * R(Ω)
- V=Voltage (EMF), in volts
- I=Electrical Current (Amperage), in amps
- R=Resistance, in ohms
- Impedance: Z(Ω)=√[R²(Ω)²=X²(Ω²]
- Z=Impedance, in ohms
- R=Resistance, in ohms
- X=Reactance, in ohms
- Power Factor: R(Ω)/Z(Ω)
- pf=Power Factor
- R=Resistance, in ohms
- Z=Reactance, in ohms
- DC VOLTAGE DROP OF CONDUCTOR (cable) OF L LENGTH
- V = voltage drop, I = current
- R = resistance of conductor per 1000 feet
- L = length of conductor in feet
- R for 18awg = 6.51, 16awg = 4.09, 14awg = 2.58
- 12awg = 1.62, 10awg = 1.02, 8awg = 0.64
- V = I * L * (R / 1000) * 1.004
Lamp sizing:
Stage/Studio lamps are often expressed as a number representing the diameter of the lamp in 1/8s of one inch. A PAR64 Lamp has a diameter of 8". A T6 lamp is 3/4". The most common size of fluorescent tube is T8, or 1". The predecessor of the BTN fresnel lamp was the T20, 2.5". A G40 lamp is 5" at its widest diameter, and so on. The most common household lamp is the A19, 2 3/8" diameter.
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