by ericmark »
Mon Mar 10, 2008 11:37 pm
At the moment things are in flux. It was considered that supplying items like fridge and freezer should be done without earth leakage protection due to the problems if the earth leakage device should trip and food allowed to warm up then re-freeze but under the new regulations any wires buried in walls must either be protected by earth leakage trips or be of a type that if a nail was knocked into it would blow a fuse rather than electrocute the person with the nail. A new cable trade name Flexishield has come on the market but I have never seen any and I am not sure how it is terminated and if new types of socket outlets and switched spurs will be required. Any socket without an RCD protection will need a label to show what it must be used for.
In the past Grid switches were very popular to supply fridge, freezer, dishwasher, hood and cooker all from one location and the grid could also have fuses but I do not really see why the fuse should be with the switch. The fuses in a fused spur are to protect the cable not the appliance and running two or three cables from 16 or 20 amp MCB’s in the consumer unit to the grid switches would protect the cable and remove the need for any fused spurs you would just have radials. As to distance between switch and appliance it depends why it is switched. If it is the means of isolation to work on the appliance in should be visible but if the appliance can be unplugged to isolate then no limit. I have in the past feed the fridge and freezer from the same supply as the alarm so there would be an audible indication should it fail as the alarm was battery backed up, but if that also feeds to smoke alarm then you are no longer allowed to feed a socket from the same RCD so either it would need spur connection units or wired in Flexishield or one of the other armoured cables. I am assuming a completion date after 1st July 2008. With most of us electricians still studying BS7671:2008 we are still finding changes we had not noticed on first read. The Part P regulations have not yet been re-written and NHBC I expect will be similar. The interpretation is a problem and at the moment consumer units with three neutral bars with two RCD’s a RCBO and main switch seems to be favoured as complying. It is plain that not all circuit are to go through one RCD and sockets and smoke alarms must not use same RCD/RCBO but only way to be 100% sure is to fit all RCBO’s which would be expensive. There seem to be already new products hitting the market place like auto-resetting RCD’s and it would be a very brave man to say what will be allowed. So many rules seem to be changing like in areas of likely flooding raising the heights of sockets and no longer can consumer units be tucked away under the stairs you need wheel chair access to them. I am sure in next few months all will become plain but until then you have a problem.
