Together with the protective grounding and lightning protection grounding which are typically a common grounding arrangement as per the EIC, item 1.7.55, healthcare institutions may need functional grounding for the X-ray machines, tomographs, and other equipment.
The resistance of the protective grounding is rated in the EIC, item 1.7.103, if a facility is equipped with its own air supply line, item 1.7.101, if there is an internal transformer substation in the building, and item 1.7.61, if there is a cable line from the transformer substation.
If there are medical premises of Group 1 and 2, the resistance of the grounding arrangement should provide the resistance of not more than 2.5 Ohm. And if the imported equipment is used, then according to the manufacturer's requirements, the resistance should not be more than 2 Ohm, according to Technical Circulation No. 24/2009 On Provision of Electrical Safety in Healthcare Institutions.
The installation of the functional grounding arrangement with the resistance of not more than 2 Ohm should be made at the distance of not less than 15 m from any other grounding arrangement as per the guidelines for designing healthcare institutions SNiP 2.08.02-89, item 36.
A mandatory measure also includes the arrangement of an additional equipotential bonding system in the Group 1 and 2 premises.
According to GOST 50571.28 and Technical Circulation 24/2009, all grounding arrangements should be attached to the lightning protection buses, since for the healthcare premises, the RF has strictly adopted the TN system, and the TT system is not allowed.
If you need to calculate and design the protective or functional grounding arrangement for a healthcare institution, contact the ZANDZ Technical Center to obtain calculations free of charge!