IEC 63044-3-2021 Home and building electronic systems (HBES) and building automation and control systems (BACS) – Part 3: Electrical safety requirements.
6.3.3 Protection from touch current General
NOTE Products Devices complying with IEC 62368-1 fulfil the requirements.
If the nominal voltage exceeds 25 V AC or 60 V DC or if the equipment is immersed, basic protection shall be provided for SELV and PELV circuits by insulation or barriers or enclosures.
Basic protection is generally unnecessary in normal dry conditions for
– SELV circuits where the nominal voltage does not exceed 25 V AC or 60 V DC, and
– PELV circuits where the nominal voltage does not exceed 25 V AC or 60 V DC and exposed-conductive-parts and/or the live parts are connected by a protective conductor to the main earthing terminal.
In all other cases, basic protection is not required if the nominal voltage of the SELV or PELV system does not exceed 1 2 V AC or 30 V DC.
Compliance is checked by measurement of the voltage and, if relevant, by testing the basic protection according to the product standard.
If no product standard exist, the test voltage for basic protection shall be 500 V. HBES/BACS products connected Limitation of touch current from the HBES/BACS device to an ICT network
For HBES/BACS products devices connected to an ICT network, as classified in 4.2 defined in
3.1 .1 , the appropriate requirements in IEC 62949 apply in addition to the product standard. Limitation of the touch current from the device to the dedicated HBES/BACS network
The touch current from devices supplied from the mains supply to the HBES/BACS network shall be limited to 0,25 mA r.m.s. according to IEC 621 51 :2000, 5.4.
Compliance is checked by measurement according to the test circuits in Figures 5 and 6 in IEC 62151:2000.
This test does not apply to devices where the circuit to be connected to the HBES/BACS network is connected to the protective or functional earthing terminal in the device. In this case the touch current from the device to the network is considered to be zero. Summation of touch current General
A device that provides an HBES/BACS network connection for connection of multiple items of other HBES/BACS equipment shall not create a hazard due to summation of touch current.
NOTE The background for these requirements is explained in IEC 60950-1 :2005, Annex W. The values used for these requirements are taken from IEC 61 1 40:201 6.
In these requirements, abbreviations have the following meanings:
– I is the touch current received from other equipment via a network at a port of the device;
– I is the summation of touch currents received from other equipment at all such network ports of the device;IEC 63044-3 pdf download.