Metal street furniture without an electrical supply: can it be omitted from a simultaneous-contact assessment?

Sam Kindred said:

Can metal signposts, post boxes and bollards embedded in the ground within 2.5 m of a charging vehicle be omitted from the simultaneous-contact assessment, assuming no electrical equipment or connection to another electrical earthing system, even where they may introduce true-Earth potential?

Quite simply, yes.

Reasoning (italicised terms using the definitions in BS 7671):

These might be extraneous-conductive-parts, but they have no exposed-conductive-parts.

The 'simultaneous contact' issue of Regulation 411.3.1.1 applies to simultaneously accessible exposed-conductive-parts rather than extraneous-conductive-parts.

Further, from BS 7671:2008 to present, there is no longer a need to provide 'main' protective equipotential bonding to extraneous-conductive-parts outside buildings (although an indoor car park is an example of being within a building). Having said that,  supplementary local protective bonding, if and where specified, would extend to them from simultaneously accessible exposed-conductive-parts even outside buildings

Thanks, Graham, really appreciate you clearing that up. This has been a bit of a thorn in my side for a while.

What happens for crash barriers and other galvanised metal items, and those with stainless steel bolts and the like. It does appear to be a can of worms.

The well painted postbox and and the plastic sheathed sign posts do fit the no exposed-conductive-parts" rule, along with coated cabinets etc. 

Probably needs that extra bit of careful on-site observation for the unexpected...

I suspect there's still scope for confusion for things like steel lighting columns - are they exposed- or extraneous-conductive-parts? Modern setups use sheathed cables and enclosed equipment internally so the column itself isn't required to carry fault current in the way an exposed-conductive-part would, yet it's solidly bolted to the lighting "head" - normally Class 1 - so would tend to be raised to elevated voltages during faults etc in a similar way to an exposed-conductive-part.  I think by traditional definitions the column itself would be classed as an extraneous-conductive-part, but I can see an argument that it's more like an extension of an exposed-conductive-part. (But the same could be said of many bonded extraneous-conductive-parts - outside taps for example.)

Are we drifting towards two different kinds of extraneous-conductive-parts? One that can import any kind of voltage (Earth or from faults from elsewhere) and another which can import only a local Earth potential (and therefore carries less risk where nearby exposed-conductive-parts have precautions (e.g. open-PEN devices) to limit their variation from true earth (but not from other imported potentials).

  - Andy.

Philip Oakley said:

The well painted postbox and and the plastic sheathed sign posts do fit the no exposed-conductive-parts" rule, along with coated cabinets etc. 

Until you insert a bolt or screw.

Philip Oakley said:

The well painted postbox and and the plastic sheathed sign posts do fit the no exposed-conductive-parts" rule, along with coated cabinets etc. 

or an extraneous-conductive-part?

  - Andy.

AJJewsbury said:

I suspect there's still scope for confusion for things like steel lighting columns - are they exposed- or extraneous-conductive-parts? Modern setups use sheathed cables and enclosed equipment internally so the column itself isn't required to carry fault current in the way an exposed-conductive-part would, yet it's solidly bolted to the lighting "head" - normally Class 1 - so would tend to be raised to elevated voltages during faults etc in a similar way to an exposed-conductive-part.  I think by traditional definitions the column itself would be classed as an extraneous-conductive-part, but I can see an argument that it's more like an extension of an exposed-conductive-part. (But the same could be said of many bonded extraneous-conductive-parts - outside taps for example.)

A lot of the ones I see have a protective conductor connected ... but I do take this point, is this really necessary in all cases?

AJJewsbury said:

I suspect there's still scope for confusion for things like steel lighting columns - are they exposed- or extraneous-conductive-parts? Modern setups use sheathed cables and enclosed equipment internally so the column itself isn't required to carry fault current in the way an exposed-conductive-part would, yet it's solidly bolted to the lighting "head" - normally Class 1 - so would tend to be raised to elevated voltages during faults etc in a similar way to an exposed-conductive-part.  I think by traditional definitions the column itself would be classed as an extraneous-conductive-part, but I can see an argument that it's more like an extension of an exposed-conductive-part. (But the same could be said of many bonded extraneous-conductive-parts - outside taps for example.)

A lot of the ones I see have a protective conductor connected ... but I do take this point, is this really necessary in all cases?