Electrical distribution systems within hospitals are generally one of three types:
Non-Essential or normal supply is the usual utility electrical supply with no back-up facility in the event of a supply failure. Connected devices go off until supply returns.
Within patient care areas, AS/NZS3003 requires that in most cases socket outlets supplied from a non-essential supply are coloured white.
Essential or back-up supply is the usual utility electrical supply with a generator back-up facility which provides power in the event of a supply failure. Connected devices will go off for a short period until the generator provides an alternative supply. There may also be a momentary power outage when the utility supply returns.
Within patient care areas AS/NZS3003 requires that in most cases socket outlets supplied from an essential supply are coloured red.
Maintained, UPS Supply or Vital Function is a supply which contains batteries and an uninterruptible power supply device which is continuously charged from the utility electrical supply. When the utility supply fails connected devices will remain on until the batteries are exhausted. When the utility supply returns it may take several hours for the batteries to re-charge.
Within patient care areas AS/NZS3003 requires that in most cases socket outlets supplied from a maintained supply are coloured blue.
AS/NZS3003 requires that UPS systems are connected to an Essential supply system when available. AS/NZS3003 also requires that in areas where there is continuous patient observation that an audible and visual monitoring system should be present to indicate that socket outlets and fixed wired equipment is running from a battery supply.