This question, concerning new domestic boiler installations and main protective bonding, has been answered by SELECT (Theme - HVAC):
Question: We are frequently asked to provide cross bonding between all the pipes below new domestic boilers by Gas Safe registered installers, as the people who inspect their work flag missing bonding as an installation omission.
However, these boilers invariably have a steel plate manifold that all these pipes terminate into - this effectively bonds all the pipes together. Householders complain that the bonding is unsightly, and it causes problems when pipes are boxed in as the bonding has to remain accessible.
The boiler manufacturer's instructions are universally vague when it comes to certifying that the manifold plate will offer the necessary electrical continuity. What is your view?
Answer: There is no requirement within BS 7671 to provide supplementary protective bonding to the pipework connected to domestic boilers however there is a requirement to provide main protective bonding to central heating systems although no specific detail is provided where the bonding conductor should be connected - we would advise this could be connected at the flow or return pipes of the boiler.
However in a domestic central heating installation it may be that central heating pipework is not considered as an extraneous conductive part and main protective bonding would then not be required - the decision ultimately lies with the installation designer to determine what is or is not an extraneous conductive part.
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