steel girder - extraneous?

[SparkyTris]

new installation
Supply is TNCS single phase (not that this matters)
residential timber house sitting on a concrete slab.
There is a steel I-beam, about 12 feet long, supported on wood (glue-lam) members at either end holding up part of the first floor.
the steel is structural.
the steel is isolated (by wood) from the outside and from the concrete deck.

does the current regs (17th edition I hope!) require that steel to be earth bonded?

parragraff 4.3 of the 17th OSG leads me to believe that it is not necessary due to its not being in contact with the ground.

 

[EFLImpudence]

Very unlikely that it will need bonding.

Also, presumably, it will not be accessible when the building is completed.


However, you cannot just ask if a specific object needs to be bonded.
The answer will always be "If it is an extraneous conductive part, then yes".

If you are in doubt about ANY part - pipe, girder, fire escape ladder or whatever - it should be tested and measurements taken between the part and the MET.

 

[ericmark]

The requirement to earth metal lumps has been largely dropped.

However 522.6.8 Irrespective of the depth of the cable from a surface of the wall or partitions, in an installation not intended to be under the supervision of a skilled or instructed person. a cable concealed in a wall or partition the internal construction of which includes metallic part, other than metallic fixings such as nails, screws and the like, shall:

Means really it is dependent on where cables run. It really needs some common sense rather than trying to match the regulation. If there are no cables near the beam then it does not need bonding but if for example there is even just a lighting cable close to the beam then in the future someone could hammer in a nail which could connect a live wire to the beam and as a result some one could get a shock touching something which it would seem is non electric but connected to that beam.

However if you read the bathroom part of the regs it does seem where all cables are RCD protected the requirement to earth all items is relaxed so you need to do your own risk assessment.

 

[EFLImpudence]

That would be earthing, eric.