Earthing & bonding confusion - discuss...

[JulianC]

Just a point for discussion really on a quiet Friday. In Chris Kitcher's book, Practical Guide to Inspection, Testing and Certification, it states:

"If a Minor Electrical Installation Works Certificate is necessary, there is no
requirement to upgrade the existing earthing and bonding arrangements
within an installation. Where the earthing and bonding do not comply with
the latest edition of BS 7671, it should be recorded on the Minor Electrical
Installation Works Certificate."

This appears to be backed up by the section on filling in a MEIWC in the OSG (pg.148) that states:

"4. If the existing installation lacks either an effective means of earthing or adequate main protective bonding conductors, this must be clearly stated. See Regulation 633.2"


Now this lot appears to contradict 131.8 (no addition or alteration unless earthing and bonding are satisfactory) so what gives?

 

[ezzzekiel]

well aware of everything you have just said, and my own take is if its a minor works and bonding is in place but undersized then i will either recomend its upgrade or note as a departure on mwc.

on a tns that requires eic i will leave as a min of 6mm if client refuses upgrade and note as departure (this advised by napit)

everything else will be upgraded to 10mm regardless or work doesnt get done

 

[JulianC]

Pondering 131.8 - "...earthing and bonding arrangements, if necessary for the protective measure applied for the safety of the addition or alteration, shall be adequate" - The protective measure will be ADS. So, if the measured Zs value for the modified circuit falls within the tabulated figure in the OSG then the earthing, which is necessary "for the safety of the addition or alteration" will indeed be adequate.

I wonder how many of the authors listed on Pg. 8 of the BRB actually spoke to each other when they wrote their bits of the regs?!

I need to get out more....