Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, concerning replacing a domestic fan in a bathroom, and what procedure to follow, is answered by the NICEIC:
What am I allowed to do?
1) Replace like for like with no supplementary bonding and no RCD.
2) Replace like for like and install supplementary bonding.
3) Install a SELV fan with transformer outside zones (then do I also need to run supplementary bonding to metal pipework?)
4) Install a SELV fan and an RCD-protected lighting circuit?
Answer: The 17th Edition of BS7671 allows supplementary equipotential bonding in bathrooms to be omitted, provided that three conditions, described in regulation 701.415.2, are met. These conditions are:
Disconnection times required by 411 of BS7671 are met, and all circuits are protected by 30mA RCD
All extraneous conductive parts are effectively connected to the protective bonding.
Your proposal 4 may comply, but note that 701.55 describes the current using equipment allowed in each zone. Low voltage ventilation equipment is allowed in Zone 1 provided that it is suitable for that zone in accordance with manufacturer's instructions. See also 701.512.2 equipment to have protection to at least IPX4.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link:
www.voltimum.co.uk/consult.php?universe=consult.index.questions