Electrical Safety – Earth bonding requirements - Single Dwelling and Multiple Dwelling Units A brief outline. Communal TV/Satellite Earth Bonding Safety is provided by ensuring that an aerial/satellite system is connected to the main earth terminal of a building, the same earth that all other services are connected to and relies on this connection of the aerial/satellite system to the building’s protective earth to minimise any dangerous voltages that could be present. All communal systems must be connected to the building’s main earth (MET) via a minimum of a 4mm2 copper cable and only to be carried out by a qualified electrician. Domestic System Supplementary Earth Bond - Recommendation Where a TV/Satellite system includes Class II equipment, a voltage will be present on the screen of the coaxial cable which can be minimised by the use of a supplementary bond. The small values of touch current associated with one piece of class II equipment are considered safe and will not create a problem, but several pieces of class II interconnected equipment in one household has to be considered. The cumulative touch current from a number of interconnected Class II items shouldn't exceed 3.5mA. Where touch current in excess of 3.5mA is likely, a supplementary bond is recommended to conduct the touch current to earth. Typically seven units would be the maximum recommended number of interconnected Class II units in order to keep below the 3.5mA maximum allowable touch current. All such work is a recommendation and should be completed by a suitable qualified electrician. BS EN 7671:2008, BS EN 60065:2002, BS EN 60728-11:2005, BS EN 60950-1:2006 , BS EN 60990:2000, BS EN 62305-4:2006, IEC 62368-1 Ed 1.0, Electricity at Work Regulations 1989, Directive 2006/95/EC, Health and Safety Directive. The above is for general information purposes only and as such electrical earth bonding should not be brought up for discussion on the forum. Please consult a qualified electrician if in doubt.