Bonding concrete rebar do you need too?

SW:

We have a new building containing 3 machines that wash / clean food in the early stage of a process all equipment is stainless steel.

The building is steel frame, there is an incoming 3phase distribution my question is do you need to earth the concrete slab rebar, also there appears to be no lightning rods to bond the building is this mandatory?

You would need to connect the steel frame to the main earthing terminal for equipotential bonding purposes. You may not need separate earth electrodes for LPS as the steel frame may well be a very effective electrode for a self protecting structure in and of itself


And do you need to bond the concrete rebar to the main earth bar for this installation?

Not specifically, as you wouldn't expect an internal floor to be introducing a potential that is different to earth potential - it may well be that the rebar is already effectively bonded to the columns (and hence to the MET) due to the nature of the construction


Any guidance greatly appreciated 7671 is not clear on this with respect to the rebar?

If I were looking at it, I'd be thinking of connecting the slab edge to the columns to give me some further assurance that the columns were effective lightning protection electrodes if my risk assessment showed that I needed lightning protection. That would effectively connect the re bar to the columns and via bonding to the MET - but BS 7671 wouldn't specifically require that approach - it would be beneficial as a consequence of the LPS Risk Assessment and subsequent design. It may be that you then further decide that a buried perimeter electrode tape linking the columns might be an advantage in relation to external contact with metallic cladding to (in part) equalize the potential between any rise of voltage on the cladding (under electrical fault conditions internally) an someone standing on some wet ground outside the building.

SW:

We have a new building containing 3 machines that wash / clean food in the early stage of a process all equipment is stainless steel.

The building is steel frame, there is an incoming 3phase distribution my question is do you need to earth the concrete slab rebar, also there appears to be no lightning rods to bond the building is this mandatory?

You would need to connect the steel frame to the main earthing terminal for equipotential bonding purposes. You may not need separate earth electrodes for LPS as the steel frame may well be a very effective electrode for a self protecting structure in and of itself


And do you need to bond the concrete rebar to the main earth bar for this installation?

Not specifically, as you wouldn't expect an internal floor to be introducing a potential that is different to earth potential - it may well be that the rebar is already effectively bonded to the columns (and hence to the MET) due to the nature of the construction


Any guidance greatly appreciated 7671 is not clear on this with respect to the rebar?

If I were looking at it, I'd be thinking of connecting the slab edge to the columns to give me some further assurance that the columns were effective lightning protection electrodes if my risk assessment showed that I needed lightning protection. That would effectively connect the re bar to the columns and via bonding to the MET - but BS 7671 wouldn't specifically require that approach - it would be beneficial as a consequence of the LPS Risk Assessment and subsequent design. It may be that you then further decide that a buried perimeter electrode tape linking the columns might be an advantage in relation to external contact with metallic cladding to (in part) equalize the potential between any rise of voltage on the cladding (under electrical fault conditions internally) an someone standing on some wet ground outside the building.