A straight drive up the 17th for installers

If you have lived by the 16th edition of what until now was the IEE Wiring Regulations, a new BSI document is going to change your working life. Much like a golfer leaving the 16th green with a credible par, past performance is little guide to the future as the 17th fairway stretches out before you.

The 16th edition, otherwise known as BS7671 has now been superseded. In January the Institution of Engineering and Technology (previously the IEE) published a revision called, unsurprisingly BS 7671: 2008. It comes into effect on July 1st.

This new document takes into account changes in technology and new products that have arrived in the seven years since the 16th edition was first published. It also helps align UK regulations with Euro regs (the European Electrotechnical and International Electrotechnical harmonisation documents).
        
For example, there are additional requirements to ensure the safe connection of low voltage generating sets, which would apply to Xpelair’s latest generation micro wind-turbine for example.

Whilst the new document has differences, including a slightly revised format, most users will still be familiar with the basic layout. As might have been feared, the 17th edition requires the production of a lot more documentation.

CORGI and Redring Showers have put together this quick run through the new document to help all installers, particularly those fitting electric showers:

• For example, there are specific new requirements to protect an installation against changes in voltage levels and against electromagnetic disturbances and installers should take the time to familiarise themselves with this section. 
   
• The installer may also be required to make sure that electrical installations are carried out by competent persons, or workers supervised by competent persons. If the installer doesn’t follow the manufacturer’s recommendations or fails to do a good job, then the code will have been breached. 
   
• There are also new requirements to make sure that safety services like emergency escape lighting and fire alarms are not prejudiced by anything done by the new electrical installation. 
   
• One specific new requirement is that if there is a socket of up to 20 amps (or 32 amps for mobile equipment) for use by householders, 30mA RCD protection usually has to be installed. The exceptions would include sockets dedicated to serving particular items of equipment like a fridge, for example. 
   
• A new table in chapter 41 of the 17th edition provides maximum values for RCD earth fault loop impedance. 
   
• There are also new requirements to protect low voltage systems from earth faults in associated high voltage systems. 
   
• The need for busbar trunking and powertrack systems is defined, as is the protection of cables buried in walls. If cables are less than 50mm below the surface of a wall 30m A RCD protection is required unless a skilled or instructed person is doing the job. Of course the normal methods of protection, like cables with an earthed metallic covering and mechanical protection remain valid. 
   
• Walls with metallic parts (apart from fixings) always require 30m A RCD protection. Minimum acceptable insulation resistance is also tougher with the old 0.5Mohms standard on a low voltage installation increased to 1Mohm. 
   
• Section 701 has the same scope in the 17th edition as it did in the 16th, relating to any location where there is a fixed bathroom or shower. This would include communal showers and baths in any facility as well as domestic bathrooms.  
   
• Zone 3 has disappeared like a golf ball into the proverbial lake, perhaps never to be seen again; with the upper height limit of all zones put at 2.25m – above 2.25m is considered outside all zones. 
   
• The requirement from supplementary equipotential bonding is no longer required, provided that all circuits at the location are protected by a 30mA RCD and there is continuity between the extraneous conductive parts, and the protective equipotential bonding. 
   
• Bathrooms or shower rooms now need electrical circuits with 30mA RCD protection. Conventional sockets (i.e. other than shaving sockets and BS EN 60742 units) are now allowable in certain circumstances. Low voltage socket-outlets may be installed, but must be at least 3m from the zone 1 boundary. Caravan and camping parks also require 30mA RCD protection that disconnects both live (line and neutral) conductors.  
   
• There are no restrictions as to where cables may be installed but any surface enclosures, including trunking, installed in the zones must have a minimum IPX4 rating. 
   
• With the exception of switches and controls of fixed current using equipment and the cords of pull cord switches, all equipment must be suitable for the zone in which it is installed. Zone 0 requires IPX7 ratings, zones 1 & 2 are IPX4, except in zone 2, for shaver sockets which must be to BS EN 61558-2-5 and located where direct spray from showers in unlikely. IPX5 should be used anywhere equipment may be exposed to water jets. 
   
• No switchgear or accessories are permitted in zone 0 and within zone 1 only switches for SELV circuits and equipment – max 12V a.c. rms or 30V ripple-free d.c. may be used. The safety source being outside zones 0, 1 and 2. This is the same for zone 2 except for shaver sockets as discussed above. 13 amp socket-outlets may be installed, but must be at least 3m from the zone 1 boundary. 
   
• All equipment installed in bath and shower rooms must be fixed, permanently connected and installed fully in accordance with the manufacturer’s instructions. Subject to the above conditions, all Redring instant electric and integral pumped showers are suitable for installation in zone 1.  
   
• Although existing installations may not comply with the 17th edition, this does not mean that they are deemed to be unsafe or require immediate upgrading.     

Redring Showers have put together this rough guide in association with the experts at CORGI. Together we’ve highlighted a small number of changes, to get the full picture it’s important to read the complete document.

The 17th edition costs £65 but if you don’t want to swing for that much, expect the IEE to publish simple guide notes soon.