Construction
The construction of the light towers was completed in December 1984 in a joint initiative between the MCC and the VCA (now Cricket Victoria) at a cost of approximately $4.9 million.
The MCG was first lit up at 9:30pm on the night of December 3, 1984 by the then State Premier and MCG Trustee the Honourable John Cain. The MCG light towers were first used for an event on the 17 February 1985, for a World Series Cup one-day international between Australia and England.
The light tower system comprises of six light towers which stand approximately 75 metres high (equivalent to a 24-story building) with the head frame a further 10 metres higher (85 metres overall).
The foundations for the towers consist of four reinforced concrete piers which are set down in depth from seven to 12 metres depending on the sub surface structure. Each of the hollow tubular steel towers contains about 130 tonnes of steel. The diameter reduces from 4.2 metres at the base to two metres at the top.
There are between 12 and 14 landings connecting ladders inside each tower. The head frames of the towers are angled in at 15 Degrees in order to provide optimum levels of light.
Power
Power to the light towers is supplied off an 11kV electrical ring main into a transformer inside the base of each tower, which reduces the voltage down to 415 volts. The total power consumption at any given time is approximately 1800Kilowatts.
Total Consumption for a year would be approximately 720,000kWh, this is based upon a running time of 400 hours over a twelve month term.
For comparison, your average three-bedroom home with an air conditioner and 4 family members consumes approximately 390kWh per month or 4680 kWh per year.
As mentioned above a ring main supplies the light towers and has two feeds. Should one feed trip, a manual switch is activated to reconnect power from the other feed.
The light towers do not have back up generators or UPS (uninterruptible power supply). If power were lost to the ground the light towers can be operated as its power supply is independent from the rest of the ground.
The ground does have an emergency generator but this only has the capacity to run the essential services for public lighting and communication through the public address system and scoreboard to patrons.
During the 2000 Olympic Football tournament, event organisers brought in six portable generators and attached them to each light tower for back up power purposes.
Due to the configuration of the power supply at the ground it is a highly unlikely that power would be lost to the whole ground as we have multiple feeds suppling the ground. Portions of Melbourne would also lose power if there were to be an interruption of power supply.
Lamps (Light globes)
Each light tower has an average of 140 no. 2KW (2000-Watt) Metal Halide lamps within the head frame. The number of lamps in each tower varies relative to their position to the central wicket area. The lamps have an effective life of approximately 5000 running hours and about 30 lamps on average are replaced each year.
The vertical design level of illumination is 1500 lux. The most recent checks carried out in February 2004 averaged 1800 lux. The levels of lighting are achieved by the computer generated individual setting of all 844 lamps to predetermined angles to provide maximum coverage of the arena without any shadowed or dark spot areas. Computer simulation of tower shadows was used to position towers so as to minimise shadows on the pitch area.
Average illumination is 15-20 times that of domestic lighting, which is more than sufficient for the demands of colour TV broadcasting.
The number of running hours for the light towers for a year depends upon the number of events held at night or over a day/night period i.e. football and cricket as well as other one off events like soccer, international rules, concerts, rugby etc.
Weather conditions that produce dim light can also influence whether the light towers are turned on during an event.
Taking all these factors into account and inclusive of maintenance time the light towers would run for approximately 400 hours per year.
You will notice that in the head frame of the towers where the lights are mounted that there are gaps or what appears to be blown lamps, this is in actual fact spaces where lights are not required as they would not improve the optimum level of lighting.
Where are the lights turned on? The light towers are controlled by computer program which when activated stages lighting on level by level. The Light Tower lighting system has two built in redundancies should the computer system fail:
(a) Manually turn the system on via a console located in a Plant room in the Great Southern Stand or
(b) Turn each tower on individually at the tower’s own dedicated controls located in each tower.
The lights take approximately 10 minutes to become fully illuminated. If the lights are turned off they can not be turned back on for another 15 minutes as they require time to cool down and then warm back up (re-strike time).Back to top