Q & A of the Day – Does this metal studwork need bonding?

Question: I am currently a 2391, 17th Edition subcontractor for a firm building new affordable flats and houses. The wiring method used is T&E cable clipped directly to the wooden joists. However the internal studwork up and down the stairs is metal. There is no continuity between walls and no bonding has been installed to overcome this.

My worry is that if a cable is drilled/nailed after handover, the stud wall will - in effect - become live as there is no fault path for the RCD/MCB to discriminate between. Please advise as to what course of action should be taken, because the way I see it, the walls should be bonded.

Answer: There is no requirement to bond isolated bits of metallic studwork in dwellings.

Note this earlier, very similar question, which was answered by SELECT: When wiring through or within metal stud partitions, do we need to bond the metal studs? Where is this described within BS 7671:2008, the 17th Edition Wiring Regulations?

Answer 2: No. But where metal stud partition walls are installed, and the installation is not under the supervision of a skilled or instructed person, then any cables passing through should be suitably protected by either earthed metallic protection, or a 30mA RCD.

Where the likes of thermoplastic cables pass though the metal stud partition wall, suitable bushing - such as grommets - should be used to prevent possible mechanical damage.

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