NEC Express5800 series User Manual page 9

PELV (Protected Extra-Low Voltage) Integrity: To ensure the extra-low
voltage integrity of the equipment, connect only equipment with mains-
protected electrically-compatible circuits to the external ports.
Remote Earths: To prevent electrical shock, connect all local (individual
office) computers and computer support equipment to the same electrical
circuit of the building wiring. If you are unsure, check the building wiring to
avoid remote earth conditions.
Earth Bonding: For safe operation, only connect the equipment to a building
supply that is in accordance with current wiring regulations in your country.
In the U.K., those regulations are the IEE.
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