This document compares different lighting technologies for lighting towers. Metal halide lighting is becoming outdated due to high maintenance costs from frequent bulb changes and fuel consumption. LEDs have improved but produce intense blue glare and have lower color rendering. CDM (cold cathode discharge metal) provides the best quality light with high color rendering and efficiency, directly replacing 1000W metal halide with only 150W while reducing glare. CDM produces "mesopic light" that stimulates both rod and cone cells in the eye for better visibility compared to the photopic light of other technologies. It has additional advantages including longer life, lower costs, and reducing health and safety risks from glare, flicker, and light pollution.

1. Lighting Technology Review
Metal Halide, LED & CDM

2. Metal Halide
Metal Halide has now reached the end of its useful life for use in lighting towers.
Metal Halide lighting towers are low in cost but have an expensive upkeep due to frequent bulb changes
and higher fuel consumption.
Light Source
Advantages
Disadvantages
1,000W Metal Halide
Good coverage
Low initial cost
Been in use for over 40 years
400W Metal Halide
55% saving over 1,000W
Fragile and relatively expensive bulbs
Inefficient by modern standards
Low CRI (Colour Rendition Index) starting at around 64/100)
Intense glare
Flicker from bulbs
Re-strike time
All of the above plus:
150W Metal Halide
75% saving over 1,000W
Less coverage
All of the above plus:
Even less coverage

3. LED
LED is becoming a more mature technology with
efficiency, and light to power ratios improving.
Cost has also significantly fallen in recent years
although LED still has the highest initial purchase cost.
The “penetration” of LED light is still not as good per
Watt as CDM and therefore requires higher wattage
LED’s to act as a replacement.
To replace a 1,000W Metal Halide 250W will usually
have to be used.
150W LED’s are available but will not replace 1,000W
Metal Halide on a one for one basis.
The light produced is also very Blue, creating glare and
discolouration.
Advantages
Good coverage
More efficient than Metal
Halide
Long life
Not prone to blowing
Instant on/off, no re-strike time
No flicker
Disadvantages
Still very expensive
Intense glare
Light produces at the blue end of
the spectrum
Lower Colour Rendition Index than
CDM
Still not as efficient as CDM

4. CDM
Advantages
CDM is very cheap to run and provides the best
quality of light, with the highest Colour Rendition
(96/100).
It is also the most energy efficient with 150W
directly replacing 1,000W metal Halide.
Good coverage
Very efficient (95% light to heat)
Natural daylight
No flicker
Low cost bulbs
Tough bulbs (no filament) 12-15,000
hours
Very high Colour Rendition (96/100 CRI)
Disadvantages
Re-strike time

5. Colour Rendition
Gravel Visual
400W Metal Halide
250W LED
150W CDM

6. Mesopic Light & Colour Rendition
Metal Halide
LED
CDM
Yellow discolouration
Blue discolouration
True colour

7. Photopic, Scotopic & Mesopic Light
There are three types of light when
looking at lighting towers…
Photopic: Vision under well-lit
conditions, which provides full colour
perception, and which functions
primarily due to cone cells in the eye.
Scotopic: Monochromatic (black and
white) vision in very low light, which
functions primarily due to rod cells in the
eye.
Mesopic: A combination of Photopic and
Scotopic in low lighting, which functions
due to a combination of rod and cone
cells in the eye.

8. Photopic, Scotopic & Mesopic Light
Metal Halide and LED produce only photopic light.
The type of light produced by CDM is called Scotopically enhanced, broad spectrum
light, otherwise known as Mesopic light.

9. How Mesopic Light Works
Traditional Metal Halide & LED produce Photopic light. This light has the appearance of being very bright by
reproducing the same spectrum of light that is produced by the sun and stimulates one of two types of light
receptors in the eye (Cones).
This creates a conflict between perceived brightness and actual visibility forcing the eye to switch between daylight
and low light functions, significantly reducing visibility.
The Ecolite produces Mesopic light that is detected by both types of receptor in the eye, Rods and Cones. The
stimulation of the Rods enhances light sensitivity, visual acuity and driver/operator reaction times.
By complimenting how the eye naturally works under low light conditions eye strain, headaches and fatigue are also
eliminated.
Photopic
Scotopic
Mesopic

10. Lenses Systems
95% of light is refracted through the prismatic lens into a
known pattern.
“Hot spots” and fade out areas are eliminated, allowing the
operator to illuminate a very specific area with ease whilst
reducing light pollution.
As an equal amount of light is refracted through each individual
prism, light arrives at the same destination whilst travelling
from multiple angles significantly reducing shadows.
As large, dark shadows are not cast across the illuminated
area, overall visibility is improved and the need to reposition
lights reduced.

11. Colour Rendition Index
CDM Mesopic
Colour Rendition Index is a quantitative measure of the ability
of a light source to reproduce the colours of various objects
faithfully in comparison with an ideal or natural light source.
Ecolite produces a CRI rating of 96/100, where as traditional
Metal Halide has a rating of around 64/100.
Ecolite provides the best colour rendering of any lighting tower
on the market.
1,000W MH Photopic

12. 4 x 1,000W MH Vs. CDM Glare Comparison
Metal Halide Glare (this also
applies to LED)
CDM – Reduced Glare improved
visibility
We are happy to prove this with night time demonstrations
against any other machine on the market.

13. Health & Safety
“
There are several lighting hazards in the
workplace which can affect the health
and safety of people. Typical risks from
lighting originate from
-Lighting At Work HSG38
”

14. 1,000W MH Are Hazardous for Health & Safety
Glare happens where vision is not directly impaired but there is
discomfort, annoyance, irritability or distraction the condition is called
discomfort glare. The latter is related to symptoms of visual fatigue. Both
types of glare can arise from the same source.
A surface lit by different artificial light sources, or by daylight under
changing sky conditions, may appear to vary in colour. Where colour
discrimination is required (as for some electrical work) this can affect
safety.
The eye is particularly sensitive to flicker and it is especially detectable at
the edges of the visual system’s field of view. Flicker can, depending on
individual sensitivity, be a source of both discomfort and fatigue. It may
even cause epileptic seizures in some people.
Some lamp designs also produce significant emissions at infrared and
ultraviolet wavelengths, both of which are invisible . These can cause
significant disruption to nocturnal wildlife such as bats.

15. Ecolite: Health & Safety
Prismatic lens and fewer photopic lumens reduces glare. Limited
Glare Rating (LGR) down to 15 is achievable
Colour rendition of 96/100 compared to >64/100 for 1,000W
metal halide
Combination of electronic ballast and CDM light source prevents
any flicker.
UV blocked to prevent light pollution

16. To Summarise…
CDM are superior to LED and Metal Halide because they are…
More efficient – Giving maximum fuel economy
Have higher Colour Rendition
Have Patented Prismatic Lens dramatically reduces glare
UV blocked
No Flicker
Cheaper life time costs
Direct replacement for 1,000W Metal Halide

17. Contact Us
Contact Ross Dryden for more information on Lighting Technology!
Tel: 01621 745 747
Mobile: 07712 135 842
Email: rdryden@youngmangroup.com