Are there any situations where you would not bond structural steelwork. I have some vague recollection that there may be, but can’t think what they might be.
As always, depends on the legal scenario, if its a DNO PME offered earth terminal the bonding is required with the sizing well documented in the electricity supply regulations. For those unable to access a copy a popular guide book, BS7671 has reproduced the table for its readers.
All other earthing facilities are non mandatory, so its likely that you may have come across unbonded material.
As regards an earth connection itself, the ESQCR require an effective earth always.
Are there any situations where you would not bond structural steelwork. I have some vague recollection that there may be, but can’t think what they might be.
Anyone? TIA
During construction (obviously?) - hence no PME for building sites.
Also if ADS is not used anywhere in the installation - a very rare situation of course, but does happen - I believe the old public telephone boxes were all Class II and so had no earth and no bonding (nothing to bond to) despite the metal construction,
It is worth remembering that in most circumstances, that structural metalwork will end up connected to the main earthing terminal, even without any deliberate bonding connection.
Metal electric conduit should be earthed, and is liable to be in contact with building steel.
Class one light fittings are often in contact with metal roofing or supports.
Circulating pumps should be earthed and are likely to be in contact with structural steel, via the pipes.
Electric water heaters also.
Most metal building frames are in good contact with the general mass of earth via the footings or foundations.
Thanks Broadage. Of course such connections will be fortuitous. My question arose because on a recent site it was only these fortuitous connections in place. Water and gas equipotential bonding connections were in place - I couldn’t see any such bonding of the steelwork and was wondering why it appeared to have been omitted.
