Common characteristics to analyse include the following:
• Overhead and underground services supplying the stadium
• Dedicated or shared lines supplying the stadium
• High- and low-voltage equipment capacity, age and condition
• Utility outages (local past record)
Supply arrangements to a stadium will vary. Large stadiums may be supplied by very secure, dedicated, on-site and upstream switchable dual-redundant high-voltage utility power supplies. Small stadiums may be supplied by only a single low-voltage utility power supply with little upstream redundancy. Any permutation may be appropriate, depending on the needs and context of each stadium.
However, all stadiums will require some level of redundant power. Even the smallest of stadiums must ensure that life-safety systems that require electrical power continue to operate in the event of an emergency and power failure, to guarantee the safe evacuation of all occupants. For larger stadiums, the delay or cancellation of a professional football match due to the loss of power (see Sub-Section 5.6.2) is generally considered to be unacceptable.
Primary power could be wholly or partially backed up by on-site generation equipment. It may be appropriate for the back-up to be permanently in place, or temporarily rented for relevant events. Stadiums may wish to explore the most appropriate rental or ownership model for their circumstances. The stadium’s electrical design should take all of these factors into account. Similarly, and whether back-up elements are temporary or permanent, the order of precedence and control logic for all automatic switching (cascaded switching logic) must be carefully designed and implemented to ensure that all elements operate as and when intended. When looking at power supply and demand, all stadiums should strive to achieve outstanding energy and sustainability targets and be powered from on-site and/or off-site renewable energy sources to target a net zero carbon building (refer to Sections 2.7 and 4.8 for further information).
The types of loads should be classified to help determine the amount of redundant capacity, and the type and size of the back-up equipment that the design will accommodate.
A typical breakdown of loads, and therefore the electrical design which must serve them, is predicated on their respective need for power resiliency.
In the event of a primary power failure and outage:
Non-essential and normal stadium loads
These can and will go off, for example:
• Power to food concessions
• Small power in offices
• Non-essential technology and communications systems
Event continuation/technical loads
These may experience a very short outage but will be quickly restored so that the event can continue.
With event continuation resiliency operating, the match can be completed and spectators can remain in their seats. Stadium services will likely be restricted. Power resiliency must be designed to negate the need for evacuation, even if primary power fails.
• Media working areas
• Giant video screens and scoreboards